INTRODUCTION TO THE READER • This manual is written for an experienced technician to provide technical information needed to maintain and repair this machine. • Be sure to thoroughly read this manual for correct product information and service procedures. • If you have any questions or comments, at if you found any errors regarding the contents of this manual, please contact using “Service Manual Revision Request Form” at the end of this manual. (Note: Do not tear off the form. Copy it for usage.
INTRODUCTION SAFETY ALERT SYMBOL AND HEADLINE NOTATIONS In this manual, the following safety alert symbol and signal words are used to alert the reader to the potential for personal injury of machine damage. • This is the safety alert symbol. When you see this symbol, be alert to the potential for personal injury. Never fail to follow the safety instructions prescribed along with the safety alert symbol. The safety alert symbol is also used to draw attention to component/part weights.
SECTION AND GROUP CONTENTS SECTION 1 GENERAL Group 1 Specification Group 2 Component Layout Group 3 Component Specifications SECTION 2 SYSTEM TECHNICAL MANUAL (Operational Principle) Group Group Group Group 1 2 3 4 Control System ECM System Hydraulic System Electrical System SECTION 3 COMPONENT OPERATION All information, illustrations and specifications in this manual are based on the latest product information available at the time of publication.
WORKSHOP MANUAL SECTION 1 GENERAL INFORMATION SECTION 3 BASE MACHINE (TRAVEL SYSTEM) Group 1 Precautions for DisassemGroup 1 Tire bling and Assembling Group 2 Drive Unit Group 2 Tightening Torque Group 3 Axle Group 3 Painting Group 4 Propeller Shaft Group 4 Bleeding Air from HydrauGroup 5 Brake Valve lic Oil Tank SECTION 2 BASE MACHINE (UPPER Group 6 Charging Block STRUCTURE) Group 7 Steering Pilot Valve Group 8 Steering Valve Group 1 Cab Group 9 Steering Cylinder Group 2 Counterweight SECTION 4 FRONT ATTAC
SECTION 1 GENERAL ―CONTENTS― Group 1 Specifications Group 3 Component Specifications Specifications ...........................................T1-1-1 Engine......................................................T1-3-1 Engine Accessories ..................................T1-3-5 Group 2 Component Layout Main Component (Overview) ....................T1-2-1 Main Component (Upperstructure) ...........T1-2-2 Hydraulic Component ...............................T1-3-7 Electrical Component ......................
(Blank) 4GDT-1-2
GENERAL / Specification SPECIFICATIONS M4GB-12-002 − ZW180 m³ (yd³) 2.8 (3.7) 〔BOC〕 Operating Weight kg (lb) 14200 (31300) Rated Loading Weight kg (lb) 4480 (9877) − Cummins QSB 6.7 -1 129.
GENERAL / Specification (Blank) T1-1-2
GENERAL / Component Layout MAIN COMPONENT (OVERVIEW) 1 2 3 4 5 6 12 7 11 10 9 T4GD-01-02-005 8 1 - Bucket 2 - Bell Crank 45- Head Light Front Working Light 3 - Bucket Cylinder 6- Rear Working Light (Optional) 7 - Rear Working Light 8 - Rear Combination Light (Turn Signal, Hazard Light, Clearance Light, Brake Light and Back Light) 9 - Turn Signal, Hazard Light and Clearance Light T1-2-1 10 - Lift Arm Cylinder 11 - Lift Arm 12 - Bucket Link
GENERAL / Component Layout MAIN COMPONENT (UPPERSTRUCTURE) 1 19 2 3 4 5 20 18 17 16 15 14 6 13 7 8 9 12 11 10 T4GD-01-02-006 12345- Charging Block Pilot Valve Brake Valve Steering Pilot Valve Steering Valve 678910 - Control Valve Stop Valve Pilot Shut-Off Valve Pilot Filter Engine 11 12 13 14 15 - T1-2-2 Fuel Tank Intercooler Torque Converter Cooler Fan Motor Radiator 16 17 18 19 20 - Oil Cooler Muffler Coolant Reservoir Air Cleaner Hydraulic Oil Tank
GENERAL / Component Layout MAIN COMPONENT LAYOUT (TRAVEL SYSTEM) 1 2 3 4 5 6 9 8 7 T4GD-01-02-007 123- Front Axle Propeller Shaft (Front) Steering Cylinder 45- Pump Device Transmission 67- T1-2-3 Rear Axle Propeller Shaft (Rear) 89- Steering Accumulator Brake Pressure Sensor
GENERAL / Component Layout ELECTRICAL SYSTEM (OVERVIEW) In Cab (Refer to T1-2-5.) 2 1 11 10 Engine and Fan Pump (Refer to T1-2-10.) 9 3 4 6 8 Pump Device (Refer to T1-2-11.) Drive Unit (Refer to T1-2-11.
GENERAL / Component Layout ELECTRICAL SYSTEM (IN CAB) 1 2 3 Monitor and Switches (Refer to T1-2-8.) 4 Right Consol (Refer to T1-2-7.) 6 5 T4GB-01-02-006 Controller and Relays (Refer to T1-2-6.
GENERAL / Component Layout Controller and Relays 6 T4GB-01-02-006 4 1 5 2 12 13 14 15 16 17 18 19 20 21 8 7 9 7 10 7 11 7 3 22 23 24 25 26 27 28 29 30 31 T4GD-01-02-002 T4GC-01-02-002 1- Flusher Relay 2- 9 - Parking Brake Relay 1 Option Controller (Optional) 3 - MC 10 - Parking Brake Relay 2 11 - Front Wiper Relay 4- ICF 12 - Horn Relay (A-R5) 5- Dr.
GENERAL / Component Layout Right Consol T4GD-01-02-003 2 3 4 6 5 7 1 8 9 10 18 17 16 15 14 13 12 T4GB-01-02-023 11 1- DSS (Down Shift) Switch 2 - Bucket Control Lever 3- Lift Arm Control Lever 4- FNR Switch 5- Horn Switch 6 - Auxiliary Control Lever (Optional) 7 - Quick Coupler Switch (Optional) 8 - Lift Arm Auto Leveler Downward Set Switch (Optional) 9 - Lift Arm Auto Leveler Upward Set Switch (Optional) 10 - Front Control Lock Lever 11 - Emergency Steering Check Switch (Optional) 12 -
GENERAL / Component Layout Monitor and Switches 1 2 T4GD-01-02-003 14 3 13 12 4 5 11 6 7 10 9 8 1 - Monitor Panel (Refer to T1-2-9.
GENERAL / Component Layout Monitor Panel 1 2 3 4 5 6 7 8 9 10 11 34 12 33 13 14 15 16 32 T4GD-01-02-001 31 30 29 1 - Engine Coolant Temperature Gauge 2 - Transmission Oil Temperature Gauge 3 - Left Turn Signal Indicator 4 - High Beam Indicator 5 - Working Light Indicator 6 - Right Turn Signal Indicator 7 - Monitor Display 8 - Stop Indicator 9 - Service Indicator 28 27 26 25 24 23 22 21 20 19 18 17 10 - Parking Brake Indicator 19 - Discharge Warning Indicator 28 - Engine Fail
GENERAL / Component Layout ENGINE AND FAN PUMP 1 2 3 4 5 A 6 8 7 9 12 11 View A 13 10 14 T4GD-01-02-009 1 - Common Rail Pressure Sensor 2 - Intake Manifold Pressure / Intake Manifold Temperature Sensor 3 - Coolant Temperature Sensor 4 - Injector 5 - Ambient Pressure Sensor 6 - Engine Oil Pressure Switch 7 - Engine Position Sensor (Camshaft) 8 - ECM 9 - Engine Speed Sensor (Crankshaft) 10 - Engine Oil Filter 13 - High-Pressure Pump 11 - Alternator 14 - Fan Pump T1-2-10 12 - Starter
GENERAL / Component Layout PUMP DEVICE 1 2 3 6 5 DRIVE UNIT 7 T4GB-01-02-009 4 8 9 20 13 14 15 16 17 18 19 12 11 10 T4GD-01-02-004 1 - Main Pump 6 - Steering Relief Valve 2 - Regulator 7 - Torque Converter Input Speed Sensor 8 - Air Breather 3 - Priority Valve 4 - Pump Delivery Pressure Sensor 5 - Pilot Pump 9 - Charge Pump 10 - Vehicle Speed Sensor 11 - Transmission Output Speed Sensor 12 - Transmission Middle Shaft Sensor 13 - Forward Clutch Solenoid Valve 14 - Reverse Clutch Solenoid
GENERAL / Component Layout CONTROL VALVE 5 4 1 2 3 T4GB-01-02-027 1 - Overload Relif Valve (Lift Arm: Bottom Side) 2 - Overload Relief Valve (Bucket: Bottom Side) 3 - Overload Relief Valve (Bucket: Rod Side) 4 - Make-Up Valve (Lift Arm: Rod Side) T1-2-12 5 - Main Relief Valve
GENERAL / Component Layout RIDE CONTROL VALVE (OPTIONAL) 1 2 CHARGING BLOCK 3 4 5 6 10 T4GB-01-02-014 9 8 7 T4GB-01-02-013 FAN MOTOR 11 12 13 T4GB-01-02-012 1 - Overload Relief Valve 2 - Ride Control Solenoid Valve 3 - Ride Control Accumulator 5- Service Brake Accumulator (Front) 6 - Service Brake Accumulator (Rear) 7 - Relief Valve 8 - Pilot Relief Valve 9 - Pump Torque Control Proportional Solenoid Valve 10 - Parking Brake Solenoid Valve 4 - Pilot Accumulator T1-2-13 11 - Reverse Con
GENERAL / Component Layout STEERING VALVE 1 2 T4GB-01-02-020 EMERGENCY STEERING PUMP (OPTIONAL) 3 4 5 6 T4GB-01-02-010 1 - Overload Relief Valve 2 - Overload Relief Valve 34- Electric Motor Gear Pump 5 - Check Valve T1-2-14 6- Relief Valve
GENERAL / Component Specifications ENGINE Manufacturer ............................................ Cummins Inc. Model........................................................ QSB6.7 Type.......................................................... Diesel, 4 Cycle, Water Cooled, Over Head Valve, Inline, Direct Injection, Turbo Charged Cyl. NO. - Bore×Stroke............................. 6-107 mm×124 mm (4.21 in×4.88 in) 3 3 Piston Displacement................................. 6690 cm (408 in ) -1 Rated Output ..
GENERAL / Component Specifications LUBRICATION SYSTEM Lubrication Pump Type............................. Trochoid Type Oil Filter .................................................... Strata Pore (Plastic fiber) / Spin-on Type Oil Cooler ................................................. Water Cooled Type STARTING SYSTEM Motor ........................................................ Magnetic Pinion Shift Reduction Type Voltage/Output.......................................... 24 V⋅7.
GENERAL / Component Specifications PERFORMANCE IMPORTANT: This list shows design specifications, which are not servicing standards. -1 Fuel Consumption Ratio........................... 233±12 g/kW⋅h (171±9 g/PS⋅h) @ 2200 min (rpm) -1 Maximum Output Torque .......................... 763±39 N⋅m (77.8±4 kgf⋅m) @ at approx. 1400 min (rpm) -1 No Load Speed.........................................
GENERAL / Component Specifications Engine Performance Curve (QSB6.
GENERAL / Component Specifications ENGINE ACCESSORIES RADIATOR ASSEMBLY Type.......................................................... Radiator, Inter Cooler and Torque Converter Cooler Tandem Type Assembly Oil Cooler Radiator Capacity.................................................... 9.9 L (2.6 US gal) 2 Air-Tight Test Pressure ............................. 100 kPa (1.0 kgf/cm , 14.5 psi) 2 Cap Opening Pressure............................. 49 kPa (0.5 kgf/cm , 7 psi) Weight ..............................
GENERAL / Component Specifications HYDRAULIC FAN PUMP Model........................................................ SGP1A25D2H1 Type.......................................................... Fixed Displacement Type Gear Pump Maximum Flow (Theoretical Value) .......... 55 L/min (14.51 US gpm) HYDRAULIC FAN MOTOR 2 Relief Set Pressure .................................. 20.6 MPa (210 kgf/cm ) @ 5 L/min (1.32 US gpm) SOLENOID VALVE Function....................................................
GENERAL / Component Specifications HYDRAULIC COMPONENT MAIN PUMP Type.......................................................... Bent Axis Type Variable Displacement Axial Plunger Pump Maximum Flow (Theoretical Value) .......... 209 L/min (55 US gpm) REGULATOR Type.......................................................... Hydraulic Pressure Operated Type PRIORITY VALVE 2 Relief Set Pressure .................................. 27.4 MPa (280 kgf/cm ) @ 70 L/min (18.5 US gpm) PILOT PUMP Model....................
GENERAL / Component Specifications RIDE CONTROL VALVE (OPTIONAL) Type.......................................................... Pilot Pressure Operated Type 2 Overload Relief Set Pressure................... 39.2 MPa (400 kgf/cm ) @ 50 L/min (13 US gpm) 2 Charge Cut Pressure................................ 11.3 MPa (115 kgf/cm ) RIDE CONTROL ACCUMULATOR (OPTIONAL) 3 Capacity.................................................... 4 L (244 in ) 2 Charging Pressure ................................... 2.
GENERAL / Component Specifications STEERING PILOT VALVE Type.......................................................... Orbitroll Type 3 3 Gerotor Capacity ...................................... 96 cm /rev (5.9 in /rev) STEERING ACCUMULATORｖ 3 Capacity.................................................... 0.2 L (12 in ) 2 Charging Pressure ................................... 8 MPa (82 kgf/cm ) BRAKE VALVE 2 Brake Pressure......................................... 3.
GENERAL / Component Specifications • Travel System TRANSMISSION Type.......................................................... Counter Shaft Type Gear Ratio ................................................ Forward 1st : 3.324 Forward 2nd : 1.963 Forward 3rd : 1.022 Forward 4th : 0.603 Reverse 1st : 3.324 Reverse 2nd : 1.963 Reverse 3rd : 1.022 Reverse 4th : 0.603 2 Parking Brake Release Pressure ............. 2.7 MPa (28 kgf/cm ) STANDARD AXLE (FRONT/REAR) Model..............................................
GENERAL / Component Specifications • Front Attachment CYLINDER Lift Arm (Left/Right) Rod Diameter ........................................... 75 mm (2.95") Cylinder Bore............................................ 125 mm (4.92") Stroke ....................................................... 765 mm (2'6") Fully Retracted Length ............................. 1296 mm (4'3") Plating Thickness ..................................... 30 µm (1.2 µin) T1-3-11 Bucket 85 mm (3.35") 150 mm (5.
GENERAL / Component Specifications ELECTRIC COMPONENT ENGINE OIL PRESSURE SENSOR 2 Operation Pressure .................................. 41.4 kPa (0.4 kgf/cm ) OVER HEAT SWITCH Operation Temperature ............................ 105±2 ° C (221±2 °F) COOLANT TEMPERATURE SENSOR (For Coolant Temperature Gauge) Operation Temperature ............................ 25 to 120 °C (77 to 248 °F) AIR FILTER RESTRICTION SWITCH Operation Pressure .................................. 6.3±0.
GENERAL / Component Specifications ILLUMINATION Work Light ................................................ : Halogen 24 V, 70 W Cab Light .................................................. : 24 V, 10 W Head Light ................................................ : Halogen 24 V、75/70 W Turn Signal Light ...................................... : Front : 24 V, 25 W :Rear : 24 V, 21 W Clearance Light ........................................ : 24 V, 5 W License Light ............................................
GENERAL / Component Specifications (Blank) T1-3-14
MEMO .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... ............
MEMO .................................................................................................................................................................... .................................................................................................................................................................... .................................................................................................................................................................... ............
SECTION 2 SYSTEM —CONTENTS— Group 1 Control System Group 4 Electrical System General ....................................................T2-1-1 Outline .....................................................T2-4-1 Engine Control .........................................T2-1-6 Main Circuit ..............................................T2-4-2 Pump Control .........................................T2-1-15 Electric Power Circuit ...............................T2-4-3 Transmission Control ..................
(Blank) 4GDT-2-2
SYSTEM / Control System GENERAL There are four controllers as shown below with MC – Main Controller – installed at their center. • • • • MC: Main Controller ICF: Information Controller ECM: Engine Control Module Monitor Unit The controllers are mutually connected through CAN, and each controller uploads the analog signals detected by the sensors and switches as well as the analog output signals to the solenoid valves on CAN by converting them into the digital signals.
SYSTEM / Control System MC, ECM and Monitor Unit are used for various operation controls of the body. • The analog input signals from the sensors and switches attached to devices other than the engine and monitor unit as well as the analog output signals from the solenoid valves are transmitted to MC, and converted into the digital signals to be uploaded on CAN.
SYSTEM / Control System Injectors Sensors and Switches for Vehicle Body MC ECM Engine Solenoid Valves for Vehicle Body Transmission Sensors and Switches Sensor Switches for Cab and Monitor Solenoid Valves Monitor Unit Relays for Cab Sensors and Switches Switches for Traveling Light Emitting Diode Dr.
SYSTEM / Control System The sensors and switches to detect the signals for various operation controls and their controllers are as shown below.
SYSTEM / Control System Input Signal Operation Control • FNR Lever → • Shift Switch → • Downshift Switch → • Upshift Switch → • Hold Switch → • FNR Selector Switch → • FNR Switch → • Brake Pressure Sensor → • Torque Converter Input Speed Sensor → • Torque Converter Output Speed Sensor → • Transmission Middle Shaft Sensor → • Vehicle Speed Sensor → (Refer to the SYSTEM/ECM System) Transmission Control →Neutral Control →FNR Lever Priority Control →FNR Selector Control While Traveling CAN MC →Manual Spe
SYSTEM / Control System ENGINE CONTROL The engine controls consist of the followings.
SYSTEM / Control System Engine Control System Layout Work Mode Selector Switch L Accelerator Pedal Hydraulic Oil Temperature Sensor Accelerator Pedal Sensor N P Main Pump Delivery Pressure Sensor Shift Switch MC ECM Transmission Engine Torque Converter Input Speed Sensor Torque Converter Output Speed Sensor Monitor Unit Engine Coolant Temperature Sensor T2-1-7 T4GC-02-01-002
SYSTEM / Control System Accelerator Pedal Control Purpose: To control the engine speed in response to stepping amount of the accelerator pedal. Actual Engine Speed Operation: 1. MC converts the input value from the accelerator pedal into the target engine speed and transmits it to ECM. Fast Idle 2. ECM controls the engine speed in response to the target engine speed. NOTE: Output value of the accelerator pedal sensor is 0.5 V to 4.5 V.
SYSTEM / Control System Accelerator Pedal Accelerator Pedal Sensor Transmission ECM MC Engine Monitor Unit T4GC-02-01-003 T2-1-9
SYSTEM / Control System Auto-Warming Up Control Purpose: To warm up the engine in response to the hydraulic oil temperature automatically. Actual Engine Speed Operation: 1. At start of the engine, if the hydraulic oil temperature is 0°C (32°F) or below, MC transmits the signal that the engine slow idle speed is set at -1 1100 min to ECM. Fast Idle Auto-Warming Up Speed 2. ECM increases the engine slow idle speed to -1 1100 min . 3.
SYSTEM / Control System Hydraulic Oil Temperature Sensor Transmission MC ECM Engine Monitor Unit Engine Coolant Temperature Sensor T4GC-02-01-004 T2-1-11
SYSTEM / Control System Engine Torque Control Purpose: To improve fuel consumption rate by changing the torque curve in response to the input signals from the work mode selector switch, shift switch and vehicle speed sensor Engine Torque 1 Operation: 2 1. When MC receives the signal of the selected work mode, MC detects the shift point. 2. MC has programmed torque curves to be selected in response to the combination of work mode and speed shift.
SYSTEM / Control System Work Mode Selector Switch L N P Shift Switch MC ECM Transmission Engine Monitor Unit T4GD-02-01-007 NOTE: The illustration shows the signal flow while mode L of work mode selector switch and speed 1 of the shift switch are selected.
SYSTEM / Control System (Blank) T2-1-14
SYSTEM / Control System PUMP CONTROL The pump controls consist of the followings.
SYSTEM / Control System Standard Torque Control Purpose: To utilize engine output power by changing pump delivery flow rate in response to increase or decrease of engine speed and hydraulic oil temperature effectively. Operation: 1. When the accelerator pedal is depressed, MC calculates the target engine speed. 2. MC calculates the pump maximum displacement angle by receiving the target engine speed signal and hydraulic oil temperature, and transmits the signal to the pump torque control solenoid valve.
SYSTEM / Control System Accelerator Pedal Accelerator Pedal Sensor Hydraulic Oil Temperature Sensor MC ECM Engine Transmission Main Pump Regulator Pump Torque Control Solenoid Valve Monitor Unit T4GD-02-01-009 T2-1-17
SYSTEM / Control System Torque Decrease Control Purpose: To utilize engine output power by changing pump delivery flow rate in response to increase or decrease of the engine speed due to traveling load effectively. Operation: 1. When the accelerator pedal is depressed, MC calculates the target engine speed. 2.
SYSTEM / Control System Accelerator Pedal Accelerator Pedal Switch Hydraulic Oil Temperature Sensor Main Pump Delivery Pressure Switch MC ECM Engine Transmission Main Pump Regulator Pump Torque Control Solenoid Valve Torque Converter Output Speed Sensor Monitor Unit Torque Converter Input Speed Sensor T4GD-02-01-010 T2-1-19
SYSTEM / Control System TRANSMISSION CONTROL The transmission controls consist of the followings.
SYSTEM / Control System Transmission Control System Layout Key Switch Travel Mode Switch Brake Pressure Sensor Accelerator Pedal Sensor M Brake Pedal Accelerator Pedal 1-4L 2-4N 1-4H Clutch Cut Position Switch Forward Clutch Solenoid Valve Transmission Middle Shaft Sensor OFF S Reverse Clutch Solenoid Valve Transmission N D MC ECM Engine 1 2 3 4 Parking Brake Speed Shift Solenoid Valve Shift Switch Parking Brake Pressure Sensor Monitor Unit Parking Brake Solenoid Valve Vehicle Speed Sens
SYSTEM / Control System Neutral Control Purpose: To protect transmission by restricting clutch connection despite operation of FNR lever or FNR switch while applying the parking brake. Operation: 1. When either of the signal from FNR lever, forward signal or reverse signal of the FNR switch is transmitted to MC, MC confirms the detected value of the parking brake pressure sensor.
SYSTEM / Control System Forward Clutch Solenoid Valve MC Reverse Clutch Solenoid Valve ECM Engine Transmission Parking Brake Pressure Sensor Monitor Unit Parking Brake Solenoid Valve Parking Brake FNR Lever F N R FNR Switch F N OFF ON R ON OFF FNR Selector Switch Parking Brake Switch NOTE: The illustration shows the signal flow in case forward of the FNR lever have been selected with the parking brake switch OFF (Transmitting brake release signal).
SYSTEM / Control System FNR Lever Priority Control Purpose: To smoothen danger-preventive function in forward/reverse operation by giving priority to the signal from FNR lever over the signal from FNR switch Operation: 1. In case the FNR lever is operated while traveling by using the FNR switch, MC disables operation of the FNR switch, and makes forward/reverse control by the input signal from the FNR lever. 2.
SYSTEM / Control System Forward Clutch Solenoid Valve MC Reverse Clutch Solenoid Valve ECM Engine Transmission Monitor Unit FNR Lever F N R FNR Switch F N OFF R ON FNR Selector Switch T4GC-02-01-011 NOTE: The illustration shows the signal flow in case forward of the FNR selector lever has been selected while traveling reverse of the FNR lever.
SYSTEM / Control System Forward/Reverse Selector Control while Traveling Purpose: To protect the transmission by preventing forward/reverse selector unless the vehicle speed is lowered than the set speed when traveling over the set speed. Operation: 1. In case the FNR lever is turned to reverse while traveling forward speed is higher than the allowable speed of FNR clutch selection, MC reduces the vehicle speed shift by sending the speed shift signal in order from 4→3→2 if the speed was set in speed 4. 2.
SYSTEM / Control System Accelerator Pedal Sensor Brake Pressure Sensor Accelerator Pedal Brake Pedal Shift Switch Forward Clutch Solenoid Valve MC Reverse Clutch Solenoid Valve ECM Engine 1 2 3 4 Speed Shift Solenoid Valve Vehicle Speed Sensor Transmission Monitor Unit FNR Lever F N R FNR Switch F N OFF R ON FNR Selector Switch T4GC-02-01-012 NOTE: The illustration shows the signal flow in case the FNR lever is set in reverse and the brake pedal is depressed while traveling forward at speed
SYSTEM / Control System Manual Speed Shift Control Purpose: To shift the speed manually Operation: 1. When manual (M) of the travel mode switch is selected, MC is provided with voltage of 1V. 2. The manual speed shift program is started in MC. 3. The shift switch is a rotary type and has two switches inside. When one of a speed among speed 1 through speed 4 is selected, the signal of the selected shift position is transmitted to MC according to the combination of ON of the shift switches.
SYSTEM / Control System Travel Mode Switch Accelerator Pedal Sensor M Brake Pressure Sensor Brake Pedal Accelerator Pedal 1-4L 2-4N 1-4H Shift Switch Forward Clutch Solenoid Valve MC ECM Engine 1 2 3 4 Speed Shift Solenoid Valve Monitor Unit Transmission Vehicle Speed Sensor FNR Lever F N R FNR Switch F N OFF R ON FNR Selector Switch T4GC-02-01-013 NOTE: The illustration shows the signal flow when the FNR lever is set in forward while the travel mode switch is set in manual and the speed
SYSTEM / Control System Automatic Speed Shift Control Purpose: To shift the speed automatically with three kinds of timing selection of automatic speed shift change Operation: 1. If either of 1-4L, 2-4N and 1-4H of the travel mode switch is selected, MC is supplied with votage according to the selected mode. Mode Auto 1-4L Auto 2-4N Auto 1-4H Output Voltage 2V 3V 4V 4.
SYSTEM / Control System Travel Mode Switch Accelerator Pedal Sensor M Brake Pressure Sensor Brake Pedal Accelerator Pedal 1-4L 2-4N 1-4H Shift Switch Forward Clutch Solenoid Valve Transmission MC ECM Engine 1 2 3 4 Speed Shift Solenoid Valve Vehicle Speed Sensor Monitor Unit Torque Converter Input Speed Sensor FNR Lever Torque Converter Output Speed Sensor F N R FNR Switch F N OFF R ON FNR Selector Switch T4GC-02-01-014 NOTE: The illustration shows the signal flow when the travel mode sw
SYSTEM / Control System Downshift Control Purpose: To lower the speed shift by pushing the switch installed at the right console. Operation: 1. When traveling at speed 4 while the travel mode switch is set in auto 1-4L mode, the signal is transmitted to MC by pushing the downshift switch once. 8. In case of the following, the downshift switch control is canceled.
SYSTEM / Control System Travel Mode Switch Accelerator Pedal Sensor Brake Pressure Sensor M Brake Pedal Accelerator Pedal 1-4L 2-4N 1-4H Shift Switch Transmission Middle Shaft Sensor Forward Clutch Solenoid Valve Reverse Clutch Solenoid Valve MC ECM Engine 1 2 3 4 Speed Shift Solenoid Valve Transmission Monitor Unit Vehicle Speed Sensor FNR Lever F N R FNR Switch F N OFF DOWN R ON UP FNR Selector Switch Upshift/Downshift Switch NOTE: The illustration shows the signal flow when MC transmit
SYSTEM / Control System Upshift Control Purpose: To raise the speed shift by putting the left hand on the steering wheel and pushing the switch installed at the right console Operation: 1. MC receives a signal by pushing the upshift switch once when traveling with speed 1 while the travel mode switch is set in auto 1-4L mode and the shift switch is set in speed 4. 2. MC transmits the signal to the speed shift solenoid valve of speed 2, and shifts up the vehicle speed. 3.
SYSTEM / Control System Travel Mode Switch Accelerator Pedal Sensor M Brake Pressure Sensor Brake Pedal Accelerator Pedal 1-4L 2-4N 1-4H Shift Switch Forward Clutch Solenoid Valve Reverse Clutch Solenoid Valve MC ECM Engine 1 2 3 4 Speed Shift Solenoid Valve Transmission Monitor Unit FNR Lever F N R FNR Switch F N OFF DOWN R ON UP HOLD FNR Selector Switch Upshift/Downshift Switch Hold Switch NOTE: The illustration shows the signal flow when MC transmits a signal to speed 2 solenoid valv
SYSTEM / Control System Clutch Cut Control Purpose: To release the FNR clutch of the transmission in order to make the most of the engine torque by operating the brake during operation of the front attachment. Depressing amount of stepping the brake at the time of declutching can be selected from among three kinds depending on the operator’s preference. 5.
SYSTEM / Control System Brake Pressure Sensor Brake Pedal Clutch Cut Position Switch OFF Forward Clutch Solenoid Valve S N Reverse Clutch Solenoid Valve D MC ECM Engine Transmission Monitor Unit T4GC-02-01-017 NOTE: The illustration shows the signal flow in case the brake pedal has been depressed in mode S of the clutch cut position switch.
SYSTEM / Control System Speed Shift Holding Control Purpose: To hold the speed shift while towing or traveling uphill. Operation: 1. When the hold switch is pushed once, the signal is transmitted to MC. 2. MC continues to transmit the signal to the speed shift solenoid valve of each time, and after that, the speed shift is fixed although if the accelerator pedal or the brake pedal is depressed.
SYSTEM / Control System Key Switch Travel Mode Switch Brake Pressure Sensor Accelerator Pedal Sensor M Brake Pedal Accelerator Pedal 1-4L 2-4N 1-4H Shift Switch Forward Clutch Solenoid Valve MC ECM Engine 1 2 3 4 Speed Shift Solenoid Valve Transmission Monitor Unit FNR Lever F N R FNR Switch F N OFF DOWN R ON UP FNR Selector Switch Upshift/Downshift Switch ON HOLD OFF Hold Switch Parking Brake Switch T4GC-02-01-018 T2-1-39
SYSTEM / Control System (Blank) T2-1-40
SYSTEM / Control System OTHER CONTROLS The other controls consist of the following.
SYSTEM / Control System Hydraulic Fan Cooling Control Purpose: To improve fuel consumption rate and noise reduction by restricting the hydraulic fan speed in response to each oil temperature and coolant temperature. Operation: 1. When the engine is started, the fan pump rotates and delivers oil to the fan motor. 2.
SYSTEM / Control System At oil temperature or coolant temperature above the set temperature (Uncontrolled speed operation) Fan Motor Flow Rate Control Valve Hydraulic Oil Tank Flow Rate Control Solenoid Valve Hydraulic Oil Temperature Sensor Fan Pump Engine Coolant Temperature Sensor Fresh Air Temperature Sensor MC ECM Engine Air Conditioner Control Panel Transmission Monitor Unit Torque Converter Oil Temperature Sensor T4GC-02-01-019 At oil temperature or coolant temperature below the set tempe
SYSTEM / Control System Hydraulic Fan Cleaning Control Purpose: To clean the radiator and oil cooler by reversing the hydraulic fan in order to blow away dust in case cleaning of the radiator and oil cooler are needed. Operation: 1. When the engine is started after the following conditions exist and the fan reverse rotation switch is turned ON, the signal is transmitted from MC to the reverse rotation control solenoid valve. 2.
SYSTEM / Control System During cooling operation (Normal rotation) Fan Motor Reverse Rotation Spool Reverse Rotation Control Solenoid Valve Engine Transmission Hydraulic Oil Tank T4GB-02-01-007 During cleaning operation (Reverse rotation) Fan Motor Reverse Rotation Spool Reverse Rotation Control Solenoid Valve Hydraulic Oil Tank Engine Transmission Parking Brake Solenoid Valve MC ECM OFF Parking Brake Pressure Sensor ON Monitor Unit Fan Reverse Rotation Switch F F N N ON R R OFF FNR
SYSTEM / Control System Transmission Failure Indicator Control • Torque converter input speed sensor • Torque converter output speed sensor • Vehicle speed sensor • Transmission middle shaft sensor • FNR lever • FNR switch Purpose: To light the transmission failure indicator on the monitor unit for protection of the transmission in case of disorder of parts likely to cause damage to the transmission Operation: In case any of the parts shown in the right becomes out of order, MC transmits the signal to the
SYSTEM / Control System FNR Switch Enable Indicator Control Purpose: To light the FNR switch enable indicator on the monitor when the FNR switch is effective. NOTE: In case the FNR lever is operated while traveling by using the FNR switch, input to the FNR switch becomes ineffective and the vehicle body moves by operating the FNR lever. (Refer to the FNR Lever Priority Control.) Operation: 1. Turn the FNR selector switch ON after the FNR lever and the FNR switch are positioned at neutral.
SYSTEM / Control System Reverse Traveling Alarm Control (Refer to the SYSTEM/Electric System group.) Purpose: To sound the alarm buzzer when reverse of the FNR lever or the FNR switch is selected. Operation: 1. When reverse of the FNR lever or the FNR switch is selected, MC grounds the terminal from the reverse light relay. 2. The reverse light relay is excited, and current flows to the reverse light and the reverse buzzer.
SYSTEM / Control System Parking Brake Indicator Control Purpose: To light the parking brake indicator on the monitor unit during parking brake operation. NOTE: The parking brake of the vehicle body is released if pilot pressure is routed. Operation: NOTE: As for operation circuit of the parking brake, refer to the SYSTEM/Electric System group. 1. When the parking brake switch is turned ON, MC confirms the signal of the parking brake pressure sensor. 2.
SYSTEM / Control System (Blank) T2-1-50
SYSTEM / Control System CONTROL BY ELECTRIC AND HYDRAULIC COMBINED CIRCUIT The electric and hydraulic combined circuit has the following controls.
SYSTEM / Control System Ride Control (Optional) Purpose: To reduce fatigue of the operator by organizing a damper circuit in the lift arm cylinder and reducing shock when traveling on rough roads Operation: 1. When the ride control switch is turned ON, MC makes the ride control effective and the ride control indicator on the monitor is lit. 2. At vehicle speed of 7 km/h (4 mph) and above, MC receives the signal from the vehicle speed sensor and transmits current to the ride control solenoid valve. 3.
SYSTEM / Control System Lift Arm Cylinder MC ECM Engine Monitor Unit Ride Control Switch To Control Valve Vehicle Speed Sensor Ride Control Accumulator OFF ON Transmission Ride Control Indicator Relief Valve Ride Control Valve Ride Control Solenoid Valve Spool Pilot Pump Hydraulic Oil Tank T4GD-02-01-003 T2-1-53
SYSTEM / Control System Bucket Auto-Leveler Control Purpose: Automatically to tilt the bucket at a proper angle (horizontal) to start digging when returning the bucket to the tilting position Operation: 1. When bucket dump operation is carried out, the bar is located in front of the bucket proximity switch. While the bar passes near the bucket proximity switch, the bucket proximity switch is turned ON. This excites the leveler relay and electromagnet at the bucket tilt side in the pilot valve. 2.
SYSTEM / Control System Bucket Cylinder Bar Bucket Proximity Switch Leveler Relay From Fuse #6 of Fuse Box B Control Valve Bucket Pilot Valve Bucket Electromagnet on Bucket Tilting Side Pilot Pump Lift Arm Main Pump T2-1-55 Hydraulic Oil Tank T4GD-02-01-001
SYSTEM / Control System Lift Arm Float Control Purpose: Free to raise and lower the lift arm in response to the external force in order to remove snow and clean road. Operation: 1.
SYSTEM / Control System Lift Arm Cylinder Bottom Side Port Rod Side Port Control Valve From Fuse #6 of Fuse Box B Electromagnet on Lift Arm Lowering Side Bucket Lift Arm Pilot Valve Lift Arm Pilot Pump Main Pump T2-1-57 Hydraulic Oil Tank T4GB-02-01-014
SYSTEM / Control System Lift Arm Kick-Out Control Purpose: Automatically to locate the lift arm at proper height when returning the lift arm to the highest position. Operation: 1. When lowering the lift arm, the plate is located in front of the lift arm proximity switch. When the plate is passing near the lift arm proximity switch, the lift arm proximity switch is turned ON. Therefore, the kick-out relay and the electromagnet at the lift arm raise side are excited. 2.
SYSTEM / Control System Plate Lift Arm Proximity Switch Lift Arm Cylinder Bottom Side Port Rod Side Port Control Valve From Fuse #6 of Fuse Box B Bucket Lift Arm Pilot Valve Lift Arm Pilot Pump Electromagnet on Lift Arm Raise Side Main Pump T2-1-59 Hydraulic Oil Tank T4GD-02-01-002
SYSTEM / Control System Lift Arm Auto-Leveler Upward Control (Optional) Purpose: To locate the lift arm between the horizon and the highest position Operation: 1. If the SET position of the lift arm auto-leveler upward set switch is selected after the lift arm is located within the allowable location of the lift arm auto-leveler (a’ in the illustration), the signal from the lift arm angle sensor is memorized by MC, and that is the lift arm auto-leveler upward stop location.
SYSTEM / Control System Link Lift Arm Angle Sensor Lift Arm Cylinder Bottom Side Port Rod Side Port Lift Arm Auto-Leveler Upward Set Switch OFF SET ON Control Valve D-10 B-11 MC B-20 Bucket A-25 Electromagnet on Lift Arm Raise Side From Fuse #6 of Fuse Box B Lift Arm Lift Arm Pilot Valve Pilot Pump Main Pump T2-1-61 Hydraulic Oil Tank T4GB-02-01-016
SYSTEM / Control System Lift Arm Auto-Leveler Downward Control (Optional) Purpose: To locate the lift arm between the horizon and the lowest position. Operation: 1. If the SET position of the lift arm auto-leveler downward set switch is selected after the lift arm is located within the allowable location of the lift arm auto-leveler (b’ in the illustration), the signal from the lift arm angle sensor is memorized by MC, and that is the lift arm auto-leveler downward stop position.
SYSTEM / Control System Link Lift Arm Angle Sensor Lift Arm Cylinder Bottom Side Port Rod Side Port Lift Arm Auto-Leveler Downward Set Switch OFF SET ON D-10 Control Valve B-19 MC B-3 B-22 Bucket Electromagnet on Lift Arm Lowering Side From Fuse #6 of Fuse Box B Lift Arm Pilot Valve Lift Arm Pilot Pump T4GB-02-01-017 T2-1-63
SYSTEM / Control System (Blank) T2-1-64
SYSTEM / ECM System OUTLINE • The high-pressure pump is driven by the engine and produces high-pressure fuel. • The common rail distributes high-pressure fuel produced by the high-pressure pump to the injector in each engine cylinder. • The injector injects high-pressure fuel from the common rail. ECM (Engine Control Module) receives the signals from sensors and MC (Main Controller) attached to the engine. ECM processes according to the detected signals and performs the following control to the injector.
SYSTEM / ECM System FUEL INJECTION CONTROL Purpose: To control the fuel injection according to the command signal from MC. Operation: 1. ECM detects the signals from engine speed sensor, engine position sensor, ambient pressure sensor, coolant temperature sensor, intake manifold pressure sensor, Intake manifold temperature sensor, engine oil pressure switch and common rail pressure sensor, and detects the engine operating condition. 2.
SYSTEM / ECM System Engine Speed Sensor (Crankshaft) Engine Position Sensor (Camshaft) Ambient Pressure Sensor Coolant Temperature Sensor Intake Manifold Pressure Sensor Intake Manifold Temperature Sensor Engine Oil Pressure Switch ECM MC Common Rail Pressure Sensor Common Rail High-Pressure Pump Injector T4GD-02-02-002 T2-2-3
SYSTEM / ECM System ENGINE START CONTROL Purpose: To control time for continuity of current for the intake air heater according to temperature in the intake manifold and improve the starting of engine. Operation: 1. The intake manifold temperature sensor sends the signals according to temperature in the intake manifold to ECM. 2. ECM controls the exciting time of intake air heater relay according to the signal. Therefore, the time for continuity of current for intake air heater is controlled.
SYSTEM / ECM System OTHER CONTROLS Other control systems consist of the following systems.
SYSTEM / ECM System Overheat Indicator Control Purpose: To light the overheat indicator on monitor unit in order to inform the abnormal rising in the engine coolant temperature to the operator. Operation: 1. When the engine coolant temperature exceeds the normal value, ECM excites the overheat relay. Therefore, terminal 1-7 of the monitor unit is grounded. 2. When terminal 1-7 of the monitor unit is grounded, the monitor unit lights the overheat indicator. 3.
SYSTEM / ECM System Engine Oil Low Pressure Indicator Control Purpose: To light the engine oil pressure indicator on monitor unit in order to inform the pressure lowering in engine lubricant oil to the operator. Operation: 1. When the engine lubricant oil pressure becomes lower than the normal range, ECM excites the engine oil pressure relay. Therefore, terminal 1-8 of the monitor unit is grounded. 2.
SYSTEM / ECM System Engine Warning Indicator Control Purpose: To light the engine warning indicator on monitor unit in order to inform the engine failure detected by ECM to the operator. Operation: 1. When detecting the engine failure, ECM grounds terminal #44. Therefore, terminal 2-21 of the monitor unit is grounded. 2. When the monitor unit terminal is grounded, the monitor unit lights the engine warning indicator. 3.
SYSTEM / ECM System Engine Warning Indicator and Stop Indicator Control Purpose: To light the engine warning indicator and stop indicator on monitor unit in order to inform the engine serious failure detected by ECM to the operator. Operation: 1. When detecting the engine serious failure, ECM grounds terminal #43. Therefore, terminals 2-21 and 2-22 of the monitor unit are grounded. 2.
SYSTEM / ECM System (Blank) T2-2-10
SYSTEM / Hydraulic System OUTLINE Hydraulic system is broadly be divided into the main circuit, pilot circuit, steering circuit and hydraulic drive fan circuit. • Main Circuit Main circuit consists of the priority valve circuit, neutral circuit, single operation circuit and combined operation circuit – composed of the main pump, priority valve, control valve, cylinders, etc.
SYSTEM / Hydraulic System MAIN CIRCUIT Outline • Main pump draws and delivers hydraulic oil, from the hydraulic oil tank through the suction filter. • Delivered pressure oil flows to the steering valve and the control valve through the priority valve. • Pressure oil to the steering valve flows to the steering cylinders in response to operation of the spool in the steering valve, and the return oil flows back to the hydraulic oil tank through the steering valve.
SYSTEM / Hydraulic System Bucket Cylinder Steering Cylinder Lift Arm Cylinder Control Valve Bucket Spool Steering Valve Lift Arm Spool Priority Valve Main Pump Suction Filter Hydraulic Oil Tank T4GD-02-03-006 T2-3-3
SYSTEM / Hydraulic System Priority Valve Circuit • At stop of the engine, the priority valve spool is • When pressure at port LS2 and the spring force pushed leftward by the spring force. When the engine is started, pressure oil from the main pump flows to the steering valve through the priority valve spool, and also flows to ports LS1 and LS2 through orifices 1 and 2 respectively.
SYSTEM / Hydraulic System Bucket Cylinder Steering Cylinder Lift Arm Cylinder Steering Valve Control Valve Hydraulic Oil Tank Bucket Spool Hydraulic Oil Tank Lift Arm Hydraulic Oil Tank Priority Valve Spring Orifice 2 Orifice 1 Orifice 3 LS 1 Spool LS 2 At Stop of Engine Main Pump NOTE: This illustration shows oil flow without operation while the engine is running.
SYSTEM / Hydraulic System Neutral Circuit • At neutral of the control lever, pressure oil from the main pump returns to the hydraulic oil tank through the neutral circuit of the control valve. • Only when the steering valve spool moves due to the priority valve, pressure oil is supplied to the steering valve. Therefore, the steering valve is not provided with a neutral circuit. (Refer to Priority Valve Circuit in this section.
SYSTEM / Hydraulic System Bucket Cylinder Steering Cylinder Lift Arm Cylinder Steering Valve Control Valve Hydraulic Oil Tank Bucket Spool Hydraulic Oil Tank Lift Arm Hydraulic Oil Tank Priority Valve Spool Main Pump T4GB-02-02-017 NOTE: This illustration shows oil flow without operation while the engine is running.
SYSTEM / Hydraulic System Combined Operation Circuit • Lift Arm Raise/Bucket Dump • When the bucket is dumped with the lift arm • • • • • raised, pilot pressure shifts the lift arm and bucket spools. Although pressure from the own pump is applied to port LS1 of the priority valve, port LS2 is not pressurized as it is connected to the hydraulic oil tank. As pressure at port LS1 is larger than the spring force of the priority valve, the spool moves rightward.
SYSTEM / Hydraulic System Steering Cylinder Bucket Cylinder Lift Arm Cylinder Steering Valve Control Valve From Pilot Valve (Bucket Dump) Bucket Orifice Hydraulic Oil Tank Lift Arm From Pilot Valve (Lift Arm Raise) Check Valve Hydraulic Oil Tank Priority Valve Spring LS 2 LS 1 Spool Main Pump T4GB-02-02-012 T2-3-9
SYSTEM / Hydraulic System • Lift Arm Raise/Right Steering • When the steering wheel is turned to the right with the lift arm raised, pilot pressure shifts the lift arm spool in the control valve and the steering valve spool. • Pressure from the own pump is applied to port LS1 of the priority valve through orifice 1. Main pressure returning from the steering valve spool through orifice 3 and the spring force are applied to port LS2.
SYSTEM / Hydraulic System Bucket Cylinder Steering Cylinder Lift Arm Cylinder Steering Valve Control Valve Hydraulic Oil Tank From Steering Pilot Valve (Right Steering) Bucket Spool Hydraulic Oil Tank From Pilot Valve (Lift Arm Raise) Lift Arm Check Valve Hydraulic Oil Tank Priority Valve Spring Orifice 2 Orifice 1 Orifice 3 LS 1 Spool LS 2 Main Pump T4GB-02-02-013 T2-3-11
SYSTEM / Hydraulic System (Blank) T2-3-12
SYSTEM / Hydraulic System PILOT CIRCUIT Outline: Pressure oil from the pilot pump is used in order to operate the circuit below.
SYSTEM / Hydraulic System Charging Block Circuit • Charging block is installed in order to supply pressure oil from the pilot pump preferentially to the service brake circuit and distribute to other pilot circuits as well. • When the engine is started, oil from the pilot pump is delivered to the charging block. • At this time, when the amount of accumulated pressure of the service brake accumulators is low, the relief valve is closed.
SYSTEM / Hydraulic System Service Brake Brake Pedal Front Brake Service Brake Accumulator Brake Valve Rear Brake Check Valves Relief Valve B Priority Valve A Spring Charging Block Pilot Pump NOTE: The illustration shows oil flow when the relief valve and the priority valve are closed in response to pressure decrease in the service brake circuit.
SYSTEM / Hydraulic System • When the service brake accumulators are • • • • • • • • pressurized to a certain amount, the relief valve opens. As port A of the priority valve is connected to the hydraulic oil tank, pressure is lost. As pressure at port B of the priority valve is larger force than the spring force, the priority valve spool moves leftward. Therefore, all pressure oil from the pilot pump is supplied to the priority valve and the circuit downstream.
SYSTEM / Hydraulic System Bucket Pilot Valve Lift Arm Pilot Valve Auxiliary Pilot Valve (Optional) Pilot Shut-Off Valve To Service Brake Circuit Service Brake Accumulator Priority Valve Relief Valve B Pilot Pump Pilot Relief Valve Hydraulic Oil Tank PS 1 PS 2 X A Spring Pump Torque Control Solenoid Valve BR3 Parking Brake Pressure Sensor Parking Brake Solenoid Valve PP Charging Block NOTE: The illustration shows the oil flow in neutral condition of the pilot valve when the service brake accumula
SYSTEM / Hydraulic System Front Attachment Operation Circuit • Pressure oil from the pilot pump flows to the • • • • charging block, comes out of port PP of the charging block and is supplied to each pilot valve through the pilot shut-off valve. The priority valve of the charging block supplies pressure oil preferentially to the service brake circuit when pressure in the service brake accumulators is lowered. (Refer to Charging Block Circuit.
SYSTEM / Hydraulic System Bucket Pilot Valve 1 2 Lift Arm Pilot Valve 3 4 Auxiliary Pilot Valve (Optional) 5 6 7 8 Control Valve Pilot Shut-Off Valve 8 Auxiliary 2 7 To Service Brake Circuit Service Brake Accumulator 6 Priority Valve 2 Auxiliary 1 5 Bucket 1 Pilot Pump 4 Slow-Return Valve Lift Arm 3 Main Pump Charging Block PP T4GD-02-03-003 NOTE: Numeral of each port of the pilot valves and the control valve shows the port to be connected.
SYSTEM / Hydraulic System Pump Control Circuit (Refer to the COMPONENT OPERATION / Pump Device group.) • Pump Control by Servo Piston Control Pressure • Servo piston control pressure (PS2) is supplied from the charging block for actuation of the servo piston of the main pump.
SYSTEM / Hydraulic System Charging Block Pilot Pump Pump Torque Control Solenoid Valve Hydraulic Oil Tank PS2 Command Signal from MC X Pump Flow Control Valve Orifice Control Valve Pi2 Pi1 Main Pump Servo Piston Main Pump Regulator T4GD-02-03-004 T2-3-21
SYSTEM / Hydraulic System Brake Circuit Service Brake Circuit (Refer to the COMPONENT OPERATION / Charging Block group.) (Refer to the COMPONENT OPERATION / Brake Valve group.) • Pressure oil from the pilot pump flows through the charging block, and is accumulated in the service brake accumulators. • By stepping the brake pedal, pressure in the service brake accumulators is applied to the front brake and the rear brake through the brake valve, and actuates the service brake.
SYSTEM / Hydraulic System Service Brake Brake Pedal Front Brake Service Brake Accumulator Brake Valve Rear Brake Check Valve Relief Valve Priority Valve Spring Parking Brake Pressure Sensor Parking Brake Solenoid Valve Parking Brake Released Pilot Accumulator No Signal for Parking Brake Release Applied Charging Block Pilot Pump NOTE: The illustration shows oil flow when the relief valve and the priority valve are open in response to pressure increase in the service brake circuit, and also oil fl
SYSTEM / Hydraulic System Ride Control Circuit (Optional) (Refer to SYSTEM / Control System Electric / the Hydraulic Combined Circuit Control in group.) • In front attachment operation, operating pressure from the lift arm cylinders is accumulated in the ride control accumulator through the charge cut spool. • When the ride control switch is turned ON, the ride control solenoid valve is excited, and the spool moves downward.
SYSTEM / Hydraulic System Ride Control Accumulator Lift Arm Cylinder To Control Valve Ride Control Valve Ride Control Operation Signal Ride Control Solenoid Valve Spool Charge Cut Spool Hydraulic Oil Tank Pilot Pump NOTE: The illustration shows oil flow when the ride control solenoid valve is excited.
SYSTEM / Hydraulic System STEERING CIRCUIT Normal Steering Circuit • Normally, pressure oil from the main pump flows to the steering valve through the priority valve. As pilot line (LS2) is connected to the hydraulic oil tank, pressure is lost. • The priority valve spool is moved to rightward pushed as pressure (LS1) from the own pump overcomes the spring force of the priority valve. Therefore, all pressure oil is supplied to the control valve.
SYSTEM / Hydraulic System Steering Cylinder Steering Accumulator Steering Valve Hydraulic Oil Tank Spool Orifice Orifice Pump Delivery Pressure Switch Steering Pilot Valve To Control Valve Gerotor Spool Priority Valve Spring Emergency Steering Pump Delivery Pressure Switch Emergency Steering Pump Unit LS 2 Steering Wheel LS 1 Pilot Pump Hydraulic Oil Tank Main Pump NOTE: The illustration shows the pressure oil flow when the steering wheel is turned to the right.
SYSTEM / Hydraulic System Steering Shockless Circuit • Pilot pressure oil supplied from the steering pilot valve to the spool end of the steering valve is reduced by passing through the orifice inside the steering valve, and is applied to the spool end of the opposite side. In this way, the vehicle shock due to sudden shift of the spool is reduced, and stable steering operation is possible. (Refer to the COMPONENT OPERATION / Steering Valve group.
SYSTEM / Hydraulic System Steering Cylinder Steering Accumulator Steering Valve Spool Orifice Orifice Pump Delivery Pressure Switch To Control Valve Steering Pilot Valve Gerotor Spool Priority Valve Spring Emergency Steering Pump Delivery Pressure Sensor Emergency Steering Pump Unit LS 2 Steering Wheel LS 1 Hydraulic Oil Tank Pilot Pump Main Pump NOTE: The illustration shows the pressure oil flow when the steering wheel is turned to the right.
SYSTEM / Hydraulic System Steering Stop Circuit (Refer to the COMPONET OPERATION / Steering Valve group.) • When either of the left or right cylinder is at the • Consequently, as the steering valve spool is in stroke end, the stop valve contacts the frame. Then the stop valve closes and pressure oil to the steering valve from the steering pilot valve is blocked. neutral, supply of pressure oil from the main pump to the steering cylinders is stopped.
SYSTEM / Hydraulic System (Blank) T2-3-31
SYSTEM / Hydraulic System HYDRAULIC DRIVE FAN CIRCUIT (Refer to the COMPONET OPERATION / Others group.) (Refer to the COMPONET OPERATION / Hydraulic Fan Motor group.) • Pressure oil from the fan pump flows to the fan • • • • • • motor through the flow control valve and the reverse rotation spool. Current corresponding to the hydraulic oil temperature is sent from MC to the flow control solenoid valve.
SYSTEM / Hydraulic System Fan Motor Reverse Rotation Spool Reverse Rotation Control Solenoid Valve Reverse Rotation Signal from MC Flow Control Valve Flow Adjusting Solenoid Valve Hydraulic Oil Tank Hydraulic Oil Tank Fan Pump Flow Adjustment Signal from MC NOTE: The illustration shows the pressure oil flow without any control.
SYSTEM / Hydraulic System (Blank) T2-3-34
SYSTEM / Electrical System OUTLINE The electrical circuit is broadly divided into the main circuit, lamplight circuit and control circuit • Main Circuit Circuit for engine start/stop, circuit for battery charging and circuit for accessories • Lamplight Circuit Circuit for traveling (composed of head lights, turn signals, brake lights and horn) • Control Circuit (Refer to the SYSTEM/Control System group.
SYSTEM / Electrical System MAIN CIRCUIT • Electric Power Circuit: for supplying electricity to the electric system as power source • Indicator Light Check Circuit: for checking monitor warning lamps and indicators • Accessory Circuit: for working at ACC of the key switch • Preheat Circuit: for assisting engine start in cold weather • Starting Circuit: for starting engine • Charging Circuit: for supplying electricity to the battery and replenishing electricity • Surge Voltage Prevention Circuit: for pre
SYSTEM / Electrical System ELECTRIC POWER SWITCH: OFF) CIRCUIT (KEY The battery ground terminal is connected to the vehicle frame. Current from the battery plus terminal flows as follows when the key switch is in the OFF position. Battery ↓ Fusible Link Although the key switch is in the OFF position, very small amount of current is supplied to the circuit. Disconnect the battery ground terminal in case of a long downtime.
SYSTEM / Electrical System INDICATOR LIGHT CHECK CIRCUIT (KEY SWITCH: ON) • When the key switch is turned to the ON position, • The monitor unit checks the bulbs breakage of terminal B is connected to terminals ACC and M inside the key switch. • Current from terminal M of the key switch flows from fuse #8 of fuse box A to terminal 1-2 of the monitor unit. warning lamp and indicator by lighting them and also starts the liquid crystal display.
SYSTEM / Electrical System ACCESSORY CIRCUIT • When the key switch is turned to the ACC position, terminal B is connected to terminal ACC inside the key switch. • Current from terminal ACC of the key switch flows from fuse #10 of fuse box B to terminal #3 of the radio and makes the radio operable.
SYSTEM / Electrical System PREHEAT CIRCUIT (KEY SWITCH: ON) • When the key switch is turned to the ON position, • • • • • • terminal B is connected to terminal M inside the key switch. Current from terminal M excites the battery relay through fuse #8 of fuse box A. The battery power is supplied to the intake-air heater relay through the fuse (120A). Current from fuse #7 of fuse box A flows to terminal #39 of ECM. ECM controls the exciting time of the intake-air heater relay.
SYSTEM / Electrical System Key Switch Fuse Box A From Fuse #7 of Fuse Box B 7 8 Intake Air Heater Relay Monitor Unit Preheat Indicator Intake Air Heater 1-24 39 40 42 50 Fuse (120A) Battery Relay Fusible Link To Fuse #7 of Fuse Box B ECM Battery T4GD-02-04-012 NOTE: The illustration shows the current flow when preheating is made with the intake-air heater relay excited and the power supplied to the intake-air heater.
SYSTEM / Electrical System STARTING START) CIRCUIT (KEY SWITCH: Operation of Starter Relay • When the key switch is turned to the START position, continuity between terminals B and ST of the key switch is made. Current flows to the base of transistor Q2 through resistance R4 inside the starter relay. Transistor Q2 is turned ON and current flows to coil L of the relay. Consequently, terminals #30 and #50 of the starter are connected and the starter is operated.
SYSTEM / Electrical System Key Switch Fuse Box A From Fuse #7 of Fuse Box B To Key ON Signal (Monitor Unit, ECM, ICF) 8 Neutral Relay MC B-16 A-27 To Fuse #7 of Fuse Box B Fuse (120A) Starter Relay Battery Relay Fusible Link Battery 30 Starter Motor G 50 Alternator T4GD-02-04-013 NOTE: The illustration shows the current flow when the FNR lever and the FNR switch are in the neutral position.
SYSTEM / Electrical System FNR Lever at Operated Position • Starting Circuit (Neutral Relay) • When the key switch is turned to the START • • • • • position, terminal B is connected to terminals M and ST inside the key switch. Current from terminal ST of the key switch flows to the neutral relay. Current from terminal M of the key switch flows to fuse #8 of fuse box A and excites the battery relay.
SYSTEM / Electrical System Key Switch Fuse Box A From Fuse #7 of Fuse Box B 8 Neutral Relay MC B-16 A-27 To Fuse #7 of Fuse Box B Fuse (120A) Starter Relay Fusible Link Battery Relay Battery Starter Motor 30 G 50 T4GD-02-04-014 NOTE: The illustration shows the current flow when either of the FNR lever or the FNR switch is in the forward or reverse position.
SYSTEM / Electrical System CHARGING CIRCUIT (KEY SWITCH: ON) • When the engine starts and the key switch is • • • • released, the key switch returns to the ON position. Terminal B is connected inside the key switch to terminals ACC and M with the key switch ON. Current from terminal M of the key switch excites the battery relay through fuse #8 of fuse box A. When the engine rotates, the alternator begins generating electricity.
SYSTEM / Electrical System Key Switch Fuse Box A From Fuse #7 of Fuse Box B Alternator Lamp Monitor Unit 8 A-3 GPS 2-2 C-8 ICF To Fuse #7 of Fuse Box B Fuse (120A) Starter Relay Fusible Link Battery Relay Battery Starter Motor 30 G 50 T4GD-02-04-015 Alternator T2-4-13
SYSTEM / Electrical System Alternator Operation • The alternator consists of field coil FC, stator coil SC and diode D. • At the beginning, no current is flowing through field coil FC. When the rotor starts rotating, alternate current is generated in stator coil SC by the rotor remanent magnetism. • When current flows through field coil FC, the rotor is further magnetized so that the generating voltage increases. Thereby, current flowing through field coil FC increases.
SYSTEM / Electrical System Alternator B L D Battery Relay B L SC F Regulator FC Battery R E T4GD-02-04-019 T2-4-15
SYSTEM / Electrical System SURGE VOLTAGE PREVENTION CIRCUIT • When the engine is stopped (key switch: OFF), • • • • • current from terminal M of the key switch is stopped and the battery relay is turned OFF. Although the key switch is turned OFF, the engine does not stop immediately due to inertia force so that the alternator continues to generate electricity.
SYSTEM / Electrical System Key Switch Load Dump Relay Fuse Box B 2-10 Monitor Unit 2-2 7 9 Fuse (120A) Starter Relay Fusible Link Battery Relay Battery Starter Motor 30 G 50 T4GD-02-04-016 Alternator T2-4-17
SYSTEM / Electrical System ENGINE STOP CIRCUIT • When the key switch is turned from the ON • The ECM relay is excited for 30 seconds after the position to the OFF position, the signal current indicating that the key switch is ON stops flowing from terminal M to terminal #39 of ECM. • ECM unexcited the fuel injection solenoid valve and the engine is stopped. key switch is OFF by the timer function. Thus, current flows to terminals #3 and #4 of ECM, and ECM is kept ON.
SYSTEM / Electrical System LAMPLIGHT CIRCUIT • Head Light Circuit: for turning on and off head lights, clearance lights and license light.
SYSTEM / Electrical System HEAD LIGHT CIRCUIT Clearance and License Light Circuit • Terminal B of the key switch is directly connected to the head light switch. • When the head light switch is positioned at (Clearance Lights), one of power from terminal S of the head light switch enters terminal 1-21 of the monitor unit and the illumination light of the monitor unit lights. • Another of power from terminal S of the head light switch is divided into to fuse #16 and fuse #17 of fuse box B.
SYSTEM / Electrical System Head Light Switch Key Switch Fuse Box A Illumination Light 1-21 Monitor Unit Front Right Clearance Light Fuse Box B Rear Right Clearance Light 7 16 17 License Light Rear Left Clearance Light Fusible Link Front Left Clearance Light Battery Battery Relay T2-4-21 Fuse (120A) T4GD-02-04-001
SYSTEM / Electrical System Head Light Lighting Circuit • When the key switch is turned to the ON position, the power from terminal M of the key switch excites the battery relay through fuse #8 of fuse box A, and the battery power flows to fuse box A and fuse Box B. • The battery power from fuse #5 of fuse box A enters the right head light relay. • The battery power from fuse #15 of fuse box A enters the left head light relay. • The battery power from fuse #12 of fuse box B enters the high beam relay.
SYSTEM / Electrical System Head Light Switch Dimmer Switch Key Switch Lo Hi High-Beam Indicator Fuse Box A Monitor Unit High-Beam Right Head Light Left Head Light Relay Relay Relay 5 1-22 8 15 Fuse Box B Right High-Beam Light 7 Right Head Light 12 Left High-Beam Light Left Head Light Fusible Link Battery Battery Relay T2-4-23 Fuse (120A) T4GD-02-04-002
SYSTEM / Electrical System TURN SIGNAL CIRCUIT • The battery power also flows to the flasher relay • The power from the flasher relay enters the front from fuse #8 of fuse box B. • When the turn signal switch is turned to left (L), terminal L of the turn signal switch is grounded and the left turn signal relay is excited. and rear left turn signal lights and terminal 1-19 of the monitor unit through the left turn signal relay.
SYSTEM / Electrical System BRAKE LIGHT CIRCUIT • When the key switch is turned to the ON position, • When the brake pedal is depressed, the brake the power from terminal M of the key switch excites the battery relay. The battery power is routed to the brake light relay through fuse #12 of fuse box A. light switch is grounded. • Therefore, the brake light relay is excited and the battery power enters the brake lights and lights them.
SYSTEM / Electrical System HAZARD LIGHT CIRCUIT • Although the key switch is OFF, the battery power • The power from the flasher relay enters all of the also flows to the flasher relay from terminal #8 of fuse box B. • When the hazard switch is turned to the ON position, the hazard switch is grounded and the left and right turn signal relays are excited. front, rear, left and right turn signal lights and terminals 1-19 and 1-20 of the monitor unit through the left and right turn signal relays.
SYSTEM / Electrical System HORN CIRCUIT • When the key switch is turned to the ON position, the power from terminal M excites the battery relay through fuse #8 of fuse box A. The battery power is routed to the horn relay through fuse #14 of fuse box A. • When the horn switch is pushed, it is grounded. • Therefore, the horn relay is excited. The battery power enters the horn and the horn sounds.
SYSTEM / Electrical System REVERSE LIGHT/BUZZER CIRCUIT • When the key switch is turned to the ON position, the power from terminal M excites the battery relay through fuse #8 of fuse box A. • The battery power enters the reverse light relay through fuse #11 of fuse box A. • When the FNR lever is turned to reverse, terminal R is grounded. The power flows to the FNR lever from terminal B-6 of MC and terminal A-26 of MC is grounded.
SYSTEM / Electrical System FNR Lever Key Switch From Fuse #7 of Fuse Box B Fuse Box A MC B-6 Reverse Light Relay 8 A-26 11 Right Reverse Light Fuse (120A) Reverse Buzzer Left Reverse Light Fusible Link Battery Relay Battery To Fuse #7 of Fuse Box B T4GD-02-04-009 T2-4-29
SYSTEM / Electrical System PARKING BRAKE CIRCUIT • When the key switch is turned to the ON position, • However, as a self-exciting circuit is formed in the power from terminal M excites the battery relay through fuse #8 of fuse box A. The battery power flows to parking brake relay 1 through fuse #2 of fuse box B. The power flows to terminal D of parking brake relay 1 through terminal B of parking brake relay 1.
SYSTEM / Electrical System Key Switch Fuse Box A From Fuse #2 of Fuse Box B 2-18 Monitor Unit 8 2-2 From Terminal L of Alternator (When forming a self-exciting circuit) ON Parking Brake Switch Parking Brake Parking Brake Relay 2 Relay 1 NEUTRAL OFF AB E F GH A B CD E 2 A B CD E 7 2-18 Monitor Unit 2-2 From Terminal L of Alternator Battery Relay Fusible Link Battery Fuse (120A) T4GD-02-04-004 NOTE: The illustration shows the current flow when the parking brake switch remains pushed after
SYSTEM / Electrical System EMERGENCY STEERING CHECK CIRCUIT (OPTIONAL) (Manual Check Circuit) • When the key switch is turned to the ON position, current from terminal M excites the battery relay. The battery power enters the emergency steering relay through fuse #6 of fuse box B and also enters terminal B of the emergency steering pump unit. • When the emergency steering check switch is turned to the ON position, current flows to terminal 1-14 of the monitor unit.
SYSTEM / Electric System Key Switch Fuse Box A 8 Emergency Steering Check Switch Emergency Steering Relay Fuse Box B Emergency Steering Pump Delivery Pressure Sensor 6 7 2-2 1-14 Emergency Steering Pump Unit 2-14 Monitor Unit Fuse (120A) Battery Relay Fusible Link Battery Alternator T4GD-02-04-010 T2-4-33
SYSTEM / Electric System (Blank) T2-4-34
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SECTION 3 COMPONENT OPERATION Group 1 Pump Device CONTENTS Group 5 Steering Valve Outline .....................................................T3-1-1 Outline .....................................................T3-5-1 Main Pump ...............................................T3-1-2 Operation .................................................T3-5-4 Regulator .................................................T3-1-4 Steering Overload Relief Valve .................T3-5-8 Priority Valve ..................
Group 7 Charging Block Group 11 Brake Valve Outline .....................................................T3-7-1 Outline ................................................... T3-11-1 Priority Valve ............................................T3-7-6 Operation ............................................... T3-11-4 Pilot Relief Valve ......................................T3-7-7 Pump Torque Control Proportional Solenoid Valve ......................................
COMPONENT OPERATION / Pump Device OUTLINE Main pump (1) is a swash plate type variable displacement axial plunger pump. Pilot pump (2) is a gear pump. Pump delivery pressure sensor (4) is provided in order to control the main pump. Pump device consists of main pump (1) and pilot pump (2). Main pump (1) has built-in steering main relief valve (5) and priority valve (6).
COMPONENT OPERATION / Pump Device MAIN PUMP The main pump supplies pressure oil to operate the cylinders and other hydraulic components. The pump is provided with a regulator to control the delivery flow. Shaft (5) is connected to cylinder block (1) in the pump. Shaft (5) and cylinder block (1) rotate together. 1 2 When cylinder block (1) rotates, plungers (2) reciprocates inside the cylinder block due to the tilting of swash plate (4), and delivers the hydraulic oil.
COMPONENT OPERATION / Pump Device Increase and Decrease Operations of Delivery Flow The displacement angle of swash plate (4) is changed by the movement of servo piston 1 (3) and servo piston 2 (6). Movement of the servo piston is controlled by the regulator. The feedback of the swash plate movement is given to the regulator by feedback lever (7) and link (8). 7 8 6 3 4 NOTE: Refer to the following pages as for operation of the regulator.
COMPONENT OPERATION / Pump Device REGULATOR The regulator controls flow of the main pump by receiving various kinds of signal pressure. The regulator includes spring (1), sleeve 1 (2), sleeve 2 (7), spool 1 (3), spool 2 (6), piston (4), load piston (5), inner spring (8) and outer spring (9). The regulator opens and closes the circuit to servo piston 1 (10) by receiving various kinds of signal pressure, and controls delivery flow of the pump by changing the displacement angle of swash plate (11).
COMPONENT OPERATION / Pump Device 2 5 4 3 6 7 10 4 - Piston 5 - Load Piston 6 - Spool 2 8 9 11 T4GB-03-01-007 12 1 - Spring 2 - Sleeve 1 3 - Spool 1 1 7 - Sleeve 2 8 - Inner Spring 9 - Outer Spring T3-1-5 10 - Servo Piston 1 (2 Used) 11 - Swash Plate 12 - Servo Piston 2
COMPONENT OPERATION / Pump Device Regulator Control Function Regulator has the following three control functions. • Control by Pump Control Pressure The pump flow control valve inside the control valve controls pump control pressure (Pi1 - Pi2) in response to the operating stroke of the control lever. The regulator increases or decreases the pump delivery flow in response to the pressure by receiving this pump control pressure (Pi1 - Pi2).
COMPONENT OPERATION / Pump Device (Blank) T3-1-7
COMPONENT OPERATION / Pump Device Control by Pump Control Pressure Decreasing Flow 1. When the control lever stroke is reduced, pressure difference (difference between pressure Pi1 and Pi2) arising at the flow control valve in the control valve is larger. 2. Pump control pressure Pi1 pushes spool 1 (3) and spool 1 (3) moves toward the arrow. 3. Therefore, primary pilot pressure Pg is led to servo piston 1 (10). 4.
COMPONENT OPERATION / Pump Device Pump Control Pressure Pi1 To Hydraulic Primary Pilot Oil Tank Pressure Pg 3 2 4 1 Pump Control Pressure Pi2 Pump Torque Control Pressure ST 13 Own Pump Pressure Pd1 12 11 10 T4GB-03-01-008 Pump Control Pressure Pi1 To Hydraulic Primary Pilot Oil Tank Pressure Pg 3 2 4 1 Pump Control Pressure Pi2 Pump Torque Control Pressure ST 13 Own Pump Pressure Pd1 12 10 11 T4GB-03-01-009 T3-1-9
COMPONENT OPERATION / Pump Device Increasing Flow 1. When the control lever stroke is larger, pressure difference (difference between pressure Pi1 and Pi2) arising at the flow control valve in the control valve is reduced. 2. Force due to spring (1) and pump control pressure Pi2 pushes spool 1 (3) and spool 1 (3) moves toward the arrow. 3. Therefore, the circuit of servo piston 1 (10) is led to the hydraulic oil tank. 4.
COMPONENT OPERATION / Pump Device Pump Control Pressure Pi1 To Hydraulic Oil Tank Primary Pilot Pressure Pg 3 2 4 1 Pump Control Pressure Pi2 Pump Torque Control Pressure ST 13 Own Pump Pressure Pd1 12 10 11 T4GB-03-01-010 Pump Control Pressure Pi1 To Hydraulic Oil Tank Primary Pilot Pressure Pg 3 2 4 1 Pump Control Pressure Pi2 Pump Torque Control Pressure ST 13 Own Pump Pressure Pd1 12 10 11 T4GB-03-01-011 T3-1-11
COMPONENT OPERATION / Pump Device Control by Own Pump Pressure Decreasing Flow 1. When load is applied to the pump due to any operation, own pump pressure Pd1 rises. (Pump control pressure (Pi1 - Pi2) remains lowered during an operation.) 2. Load piston (5) pushes spool 2 (6), inner spring (8) and outer spring (9), and spool 2 (6) moves toward the arrow. 3. Therefore, primary pilot pressure Pg is led to servo piston 1 (10). 4.
COMPONENT OPERATION / Pump Device Pump Control Pressure Pi1 5 To Hydraulic Oil Tank Primary Pilot Pressure Pg 6 7 Pump Control Pressure Pi2 Pump Torque Control Pressure ST 8 9 13 Own Pump Pressure Pd1 12 10 11 T4GB-03-01-012 5 Pump Control Pressure Pi1 To Hydraulic Oil Tank Primary Pilot Pressure Pg 6 7 Pump Control Pressure Pi2 Pump Torque Control Pressure ST 8 13 Own Pump Pressure Pd1 9 12 10 11 T4GB-03-01-013 T3-1-13
COMPONENT OPERATION / Pump Device Increasing Flow 1. When the pump load is reduced, own pump pressure Pd1 lowers. (Pump control pressure (Pi1 - Pi2) remains lowered during an operation.) 2. Load piston (5) and spool 2 (6) are pushed by inner spring (8) and outer spring (9), and spool 2 (6) moves toward the arrow. 3. Therefore, the circuit of servo piston 1 (10) is connected to the hydraulic oil tank. 4.
COMPONENT OPERATION / Pump Device 5 Pump Control Pressure Pi1 To Hydraulic Oil Tank Primary Pilot Pressure Pg 6 7 Pump Control Pressure Pi2 Pump Torque Control Pressure ST 8 13 Own Pump Pressure Pd1 9 12 10 11 T4GB-03-01-014 5 Pump Control Pressure Pi1 To Hydraulic Oil Tank Primary Pilot Pressure Pg 6 7 Pump Control Pressure Pi2 Pump Torque Control Pressure ST Own Pump Pressure Pd1 13 12 10 11 T4GB-03-01-015 T3-1-15
COMPONENT OPERATION / Pump Device Control by Pilot Pressure from Torque Control Solenoid Valve Decreasing Flow 1. Command from the MC (main controller) drives the pump torque control solenoid valve and pump torque control pressure ST enters the regulator. 2. Pump torque control pressure ST acts on load piston (5) by adding to own pump pressure Pd1. 3. Load piston (5) pushes spool 2 (6), inner spring (8) and outer spring (9), and spool 2 (6) moves toward the arrow. 4.
COMPONENT OPERATION / Pump Device 5 Pump Control Pressure Pi1 To Hydraulic Oil Tank Primary Pilot Pressure Pg 6 7 Pump Control Pressure Pi2 Pump Torque Control Pressure ST 8 9 13 Own Pump Pressure Pd1 12 10 11 T4GB-03-01-016 5 Pump Control Pressure Pi1 To Hydraulic Oil Tank Primary Pilot Pressure Pg 6 7 Pump Control Pressure Pi2 Pump Torque Control Pressure ST 8 13 Own Pump Pressure Pd1 9 12 10 11 T4GB-03-01-017 T3-1-17
COMPONENT OPERATION / Pump Device PRIORITY VALVE (Refer to the Main Curcuit in the SYSTEM / Hydraulic System group.) Before Steering Operation The main pump has a built-in priority valve. The priority valve is installed for effectively distributing the main pump delivery oil to the steering valve and the control valve. Operation 1. Before Steering Operation Pressure oil from the main pump flows to the steering valve through port CF.
COMPONENT OPERATION / Pump Device PILOT PUMP Drive gear (1) is driven via the shaft in the main pump, which rotates driven gear (2) as they are meshed together. 1 - Drive Gear 1 Inlet Port 2 2 - Driven Gear Outlet Port T137-02-03-005 PUMP DELIVERY PRESSURE SENSOR This sensor detects the pump delivery pressures, which are used in order to control various operations. When oil pressure is applied to diaphragm (6), diaphragm (6) is deformed.
COMPONENT OPERATION / Pump Device STEERING MAIN RELIEF VALVE The main pump has a built-in steering main relief valve. When the steering circuit pressure exceeds the set pressure, pressure oil is returned to the hydarulic oil tank through the main pump casing.
COMPONENT OPERATION / Control Valve OUTLINE The control valve controls pressure, flow rate and direction of oil in the hydraulic circuit. The control valve consists of the main relief valve, overload relief valve, negative control valve, restriction valve, flow rate control valve and spools, and its operation is the hydraulic pilot type.
COMPONENT OPERATION / Control Valve Component Layout 1 2 3 4 11 5 6 7 7 10 9 T3-2-2 8 T4GB-03-02-003
COMPONENT OPERATION / Control Valve A 7 6 8 9 7 5 B C D E 4 2 3 T4GB-03-02-004 1 - Bucket Flow Rate Control Valve 2 - Negative Control Valve 3 - Overload Relief Valve (Bucket: Bottom Side) 4 - Overload Relief Valve (Bucket: Rod Side) 5 - Overload Relief Valve (Lift Arm: Bottom Side) 6 - Make-Up Valve (Lift Arm: Rod Side) 7 - Restriction Valve 8 - Low-Pressure Relief Valve 9 - Main Relief Valve T3-2-3 10 - Load Check Valve (Arm Lift Circuit) 11 - Load Check Valve (Bucket Circuit)
COMPONENT OPERATION / Control Valve 1 2 3 4 11 5 6 7 7 10 9 T3-2-4 8 T4GB-03-02-003
COMPONENT OPERATION / Control Valve * Section A 8 9 7 7 2 T4GB-03-02-005 * Section B 8 9 T4GB-03-02-006 1 - Bucket Flow Rate Control Valve 2 - Negative Control Valve 3 - Overload Relief Valve (Bucket: Bottom Side) 4 - Overload Relief Valve (Bucket: Rod Side) 5 - Overload Relief Valve (Lift Arm: Bottom Side) 6 - Make-Up Valve (Lift Arm: Rod Side) 7- Restriction Valve 8- Low-Pressure Relief Valve 9- Main Relief Valve NOTE: * Refer to T3-2-3.
COMPONENT OPERATION / Control Valve 1 2 3 4 11 5 6 7 7 10 9 T3-2-6 8 T4GB-03-02-003
COMPONENT OPERATION / Control Valve * Section C 6 10 7 7 5 * Section D 1 11 4 3 * Section E 2 T4GB-03-02-007 1 - Bucket Flow Rate Control Valve 2 - Negative Control Valve 3 - Overload Relief Valve (Bucket: Bottom Side) 4 - Overload Relief Valve (Bucket: Rod Side) 5 - Overload Relief Valve (Lift Arm: Bottom Side) 6 - Make-Up Valve (Lift Arm: Rod Side) 7- Restriction Valve 8- Low-Pressure Relief Valve 9- Main Relief Valve NOTE: *Refer to T3-2-3.
COMPONENT OPERATION / Control Valve HYDRAULIC CIRCUIT Main Circuit The main circuit contains a parallel circuit, which enables combined operations. The main circuit (between the pump and the cylinder) is provided with the main relief valve. The main relief valve prevents pressure inside the main circuit from increasing over the set pressure during operation of the spool (when the control lever is operated).
COMPONENT OPERATION / Control Valve Bucket Cylinder Lift Arm Cylinder Control Valve Bucket Overload Relief Valve Lift Arm Parallel Circuit Main Relief Valve Main Pump T4GB-03-02-012 T3-2-9
COMPONENT OPERATION / Control Valve Pilot Operation Circuit Pressure oil indicated with numbers from the pilot valve acts on the spool of the control valve, and moves the spool. • Pressure oil is sent to the bucket spool for dumping and crowding operations. • Pressure oil is sent to the lift arm spool for raising and lowering operations. The spool for lowering is two-staged. The first stage is when lowering the lift arm and the second stage is when floating the lift arm.
COMPONENT OPERATION / Control Valve Bucket Pilot Valve Lift Arm Pilot Valve 1 3 2 4 Pilot Pump Control Valve Bucket 1 2 Lift Arm 4 3 Main Pump T4GB-03-02-013 1 - Bucket Crowding 2 - Bucket Dumping 34- Lift Arm Lowering Lift Arm Raising T3-2-11
COMPONENT OPERATION / Control Valve MAIN RELIEF VALVE The main relief valve prevents pressure inside the main circuit from increasing over the set pressure during operation of the cylinder. This prevents oil leakage from the hoses and piping fittings as well as cylinder breakage. Relief Operation 1. Pressure at port HP (the main circuit) acts on the pilot poppet through orifice A of the main poppet and orifice B of the seat. 2.
COMPONENT OPERATION / Control Valve Normal State: Main Poppet Orifice A Orifice B Seat Passage A Spring B HP Sleeve LP Spring Chamber Spring A T4GB-03-02-034 Pilot Poppet Relief State: Main Poppet Orifice A Orifice B Seat Passage A Spring B HP Sleeve LP Spring Chamber Spring A T3-2-13 Pilot Poppet T4GB-03-02-035
COMPONENT OPERATION / Control Valve OVERLOAD RELIEF VALVE (With Make-Up Function) The overload relief valve is provided with the circuit in the bottom side of the lift arm and the bottom and rod side of the bucket. The overload relief valve controls pressure in each front circuit in order not to rise abnormally when each front attachment is operated by external force.
COMPONENT OPERATION / Control Valve Normal State: Main Poppet Sleeve Spring A Passage A Spring B HP T4GB-03-02-030 LP Orifice Piston Spring Chamber Pilot Poppet Spring C Relief State: Main Poppet Sleeve Spring A Passage A Spring B HP LP Orifice T4GB-03-02-031 Spring Chamber Pilot Poppet Piston Make-Up Operation: Sleeve HP LP R4GB-03-02-032 Spring C T3-2-15
COMPONENT OPERATION / Control Valve Bottom Side Circuit of Lift Arm and Bucket Relief Operation 1. Pressure at port HP (the front circuit) acts on the shaft through the seat. 2. When the pressure at port HP reaches the set force of spring A, the shaft moves and pressure oil flows to port LP. 3. Consequently, the pressure in the front circuit decreases. 4. If pressure in the front circuit decreases to the set pressure, the shaft is moved by the force of spring A and the oil passage is closed.
COMPONENT OPERATION / Control Valve Normal State: Seat HP Shaft LP Spring B Spring A T4GB-03-02-027 Relief State: Seat Shaft HP LP Spring B Spring A T4GB-03-02-028 Make-Up Operation: Seat HP Shaft LP Spring B Spring A T4GB-03-02-029 T3-2-17
COMPONENT OPERATION / Control Valve (Blank) T3-2-18
COMPONENT OPERATION / Control Valve RESTRICTION VALVE The restriction valve is installed at the inlet part to the pilot circuit on the both ends of the spool for the lift arm. If the pilot valve is tuned to the neutral position during operation of the lift arm, the pilot pressure oil supplied to the spool for the lift arm is drained through the orifice of the check valve of the restriction valve. Thereby, pilot pressure gradually decreases.
COMPONENT OPERATION / Control Valve NEGATIVE CONTROL VALVE Negative Control Valve Orifice The control valve has a built-in negative control valve. The negative control valve controls delivery flow of the main pump by flow rate control pressure (Pc1 and Pc2).
COMPONENT OPERATION / Control Valve Section A * From Main Pump Pc2 Section E** Pc1 Pc2 Orifice Part Negative Control Valve T4GB-03-02-016 NOTE: *Refer to T3-2-3, T3-2-5. **Refer to T3-2-5.
COMPONENT OPERATION / Control Valve FLOW RATE CONTROL VALVE The flow rate control valve is installed in the bucket circuit, restricts the circuit during the combined operation and gives priority to operations of the other actuators. Single Operation of Bucket Crowding 1. Pressure oil from the main pump flows through the lift arm spool. 2. Pressure oil from the lift arm spool flows to the bucket spool through check valve 1 and is supplied to the bucket cylinder.
COMPONENT OPERATION / Control Valve Single Operation of Bucket Crowding Bucket Cylinder Bucket Spool Pilot Pressure Check Valve 1 Lift Arm Spool T4GB-03-02-018 Combined Operation of Bucket Crowding and Lift Arm Raising Bucket Cylinder Pilot Pressure Bucket Spool Check Valve 2 Lift Arm Cylinder Orifice Pilot Pressure Lift Arm Spool Parallel Circuit T4GB-03-02-019 T3-2-23
COMPONENT OPERATION / Control Valve (Blank) T3-2-24
COMPONENT OPERATION / Hydraulic Fan Motor OUTLINE The shaft of the fan motor is equipped with the cooling fan. Pressure oil from the fan pump rotates the cooling fan by driving the shaft. The fan motor has a built-in reverse rotation control solenoid valve and a flow rate adjustment solenoid valve, which control the motor rotation direction and rotation speed.
COMPONENT OPERATION / Hydraulic Fan Motor Component Layout Cooling Fan Shaft Fan Motor Reverse Rotation Spool Reverse Rotation Control Solenoid Valve Flow Rate Control Valve Reverse Rotation Command Signal from MC Flow Rate Control Valve Spring Flow Rate Adjustment Solenoid Valve Relief Valve Hydraulic Oil Tank Hydraulic Oil Tank Fan Pump Flow Rate Adjustment Command Signal from MC T3-3-2 T4GB-02-02-008
COMPONENT OPERATION / Hydraulic Fan Motor * Section B-B * Section C-C 5 6 7 8 9 10 * Section A-A 1 2 3 4 12 11 T4GB-03-03-002 1 - Shaft 4 - Cylinder Block 2 - Thrust Plate 3 - Piston 5 - Center Spring 6 - Valve Pｌａｔｅ 7 - Flow Rate Adjustment Solenoid Valve 8 - Flow Rate Control Valve 9 - Relief Valve *: Refer to T3-3-1.
COMPONENT OPERATION / Hydraulic Fan Motor OPERATION The fan motor is a swash plate type axial piston motor, and converts pressure oil from the fan pump into rotation. Operational Principle of Hydraulic Motor 1. Pressure oil from the fan pump is routed to cylinder block (4) through valve plate (6). 2. Pressure oil into cylinder block (4) pushes piston (3). 3.
COMPONENT OPERATION / Hydraulic Fan Motor α° F1 F3 F2 2 1 4 2 3 4 6 3 From Fan Pump To Hydraulic Oil Tank T3-3-5 T4GB-03-03-003 T4GD-03-03-001
COMPONENT OPERATION / Hydraulic Fan Motor FLOW RATE CONTROL VALVE When temperature in the coolant or oil is less than the set temperature, the flow rate control valve supplies necessary amount of pressure oil from the fan pump to the motor, and returns redundant amount of pressure oil to the hydraulic oil tank. This controls to lower the engine load and wind noise of the cooling fan. Operation 1.
COMPONENT OPERATION / Hydraulic Fan Motor 7 8 From Fan Pump P B A 12 T T4GB-03-03-005 To Hydraulic Oil Tank T3-3-7
COMPONENT OPERATION / Hydraulic Fan Motor REVERSE ROTATION CONTROL VALVE The fan motor rotates reversely by operations of the reverse rotation control solenoid valve and the reverse rotation spool. Operation • Reverse Rotation Control Solenoid Valve in Neutral 1. When reverse rotation control solenoid valve (1) is in neutral, pressure oil (P) from the fan pump is blocked by selection valve (2). 2.
COMPONENT OPERATION / Hydraulic Fan Motor In Neutral 1 P OFF 2 MB MA 4 T 3 T4GB-03-03-006 In Operation 1 P ON 2 MA MB 4 T T3-3-9 3 T4GB-03-03-007
COMPONENT OPERATION / Hydraulic Fan Motor FAN PUMP The fan pump is a gear pump and always supplies pressure oil to the fan motor when the engine is running. The fan pump is installed to the engine.
COMPONENT OPERATION / Steering Pilot Valve OUTLINE The steering pilot valve is located between the brake/pilot pump and the steering valve. The steering pilot valve supplies pressure oil from the pilot pump to the steering valve in response to the movement of the steering wheel.
COMPONENT OPERATION / Steering Pilot Valve CONSTRUCTION 8 7 11 The steering pilot valve consists of gerotor (8), drive (7), sleeve (3), spool (4), pin (5), housing (1) and centering springs (2). 10 When the steering wheel is rotated, spool (4) rotates and an oil passage is provided between spool (4) and sleeve (3). Pressure oil from the brake/pilot pump is controlled by spool (4) and sleeve (3), and flows to the steering valve. Centering springs (2) are installed to both spool (4) and sleeve (3).
COMPONENT OPERATION / Steering Pilot Valve OPERATION 4 Sleeve (3), spool (4) and drive (7) are mutually connected by pin (5). When the steering wheel (spool (4)) is turned, a relative displacement angle arises between sleeve (3) and spool (4) due to the long hole of spool (4). The movement of the steering wheel is transmitted only to spool (4), and port P (from the steering pump) is connected to port R (to the steering valve) or port L via sleeve (3) and spool (4).
COMPONENT OPERATION / Steering Pilot Valve Left Steering 4. Returning oil from the steering valve flows to port R, flows in the order of housing (1) - sleeve (3) spool (4) - sleeve (3) - port T and returns to the hydraulic oil tank. 5. When pressure oil from the brake/pilot pump flows to gerotor (8), gerotor (8) rotates to the left. Rotation of gerotor (8) is transmitted to sleeve (3) via drive (7), and sleeve (3) rotates to the left. 6.
COMPONENT OPERATION / Steering Pilot Valve Right Steering T L R P When the steering wheel is turned to the right, pressure oil from the brake/pilot pump flows in the order of port P - port R – the steering cylinder, operates the steering valve and directs the front wheel to the right. Returning oil from the steering valve flows in the order of port L - port T and returns to the hydraulic oil tank.
COMPONENT OPERATION / Steering Pilot Valve (Blank) T3-4-6
COMPONENT OPERATION / Steering Valve OUTLINE The steering valve is located between the main pump and the steering cylinder. The steering valve supplies pressure oil from the main pump to the steering cylinder in response to pilot oil pressure in the steering pilot valve. The steering cylinder is equipped with the overload relief valve.
COMPONENT OPERATION / Steering Valve Layout 4 1 2 3 Port T Port A Port B Port Pa Port Pb 5 6 Port DR Port P Port LS Port A: Right Steering Pressure Port B: Left Steering Pressure Port P: From Main Pump Port T: Returning to Hydraulic Oil Tank 4 5 Port Pa: Right Steering Pilot Pressure Port LS: To Port LS of Priority Valve T3-5-2 T4GB-03-04-002 Port Pb: Left Steering Pilot Pressure Port DR: Returning to Hydraulic Oil Tank
COMPONENT OPERATION / Steering Valve Section A * 7 Port P Port DR 1 Port T Section B * 3 Port LS Port B Port A 2 Port Pb Port Pa 4 5 7 Section C* T4GB-03-04-003 4 6 T4GB-03-04-006 1 - Spool 2 - Overload Relief Valve 3 - Overload Relief Valve 4 - Load Check Valve 5 - Variable Orifice 6 - Fixed Orifice *: Refer to T3-5-1 T3-5-3 7- Passage A
COMPONENT OPERATION / Steering Valve OPERATION In Neutral 1. When steering spool (1) is in the neutral position, port A and port B to the steering cylinder are closed. 2. Pressure oil from the main pump does not flow to the steering cylinder as port P is closed.
COMPONENT OPERATION / Steering Valve Section A * Port P Port DR Port T Section B * Port B Port A T4GB-03-04-004 1 *: Refer to T3-5-1.
COMPONENT OPERATION / Steering Valve When Steering Left 1. When the steering handle is turned to the left, pilot pressure oil is supplied to port Pb from the steering pilot valve and spool (1) moves to the right. 2. Pressure oil from the main pump is supplied to the steering valve from port P, and supplied to passage A (7) through variable orifice (5). 3. Pressure oil in passage A (7) pushes and opens load check valve (4) and flows to the steering cylinder through port B. 4.
COMPONENT OPERATION / Steering Valve Port P 1 7 5 Port T Port LS Port B Port A Port Pb Port Pa 4 6 5 7 T3-5-7 T4GB-03-04-005
COMPONENT OPERATION / Steering Valve STEERING OVERLOAD RELIEF VALVE The steering overload relief valve is installed in the left and right steering circuits. The overload relief valve controls pressure in the respective steering circuits from rising abnormally high when the steering cylinder is moved by an external force. Make-Up Operation Relief Operation 1. Pressure at port HP (steering cylinder circuit) acts on the pilot poppet through the orifice in the piston. 2.
COMPONENT OPERATION / Steering Valve During Normal Operation: Main Poppet Sleeve Spring A Passage A Spring B HP T4GB-03-02-030 LP Orifice Piston During Relief Operation: Spring Chamber Main Poppet Pilot Poppet Sleeve Spring A Spring C Passage A Spring B HP LP Orifice Piston T4GB-03-02-031 Spring Chamber During Make-Up Operation: Pilot Poppet Sleeve HP LP T4GB-03-02-032 Spring C T3-5-9
COMPONENT OPERATION / Steering Valve (Blank) T3-5-10
COMPONENT OPERATION / Pilot Valve OUTLINE (STANDARD LEVER TYPE PILOT VALVE FOR FRONT ATTACHMENT) The pilot valve is a valve to control pilot pressure oil to move the spool of the control valve. The pilot valve, which is provided with the PPC (Pressure Proportional Control Valve) function, outputs pressure corresponding to the control lever stroke of the control lever, and moves the spool of the control valve. The two-direction, four-port type is adopted for the front attachment. Port No.
COMPONENT OPERATION / Pilot Valve OPERATION E Pilot Pressure At Neutral (Pusher Stroke: Between A and B) 1. At the neutral position of the control lever, spool (7) completely blocks pressure oil of port P. As the outlet port is connected to port T through the notch part of spool (7), pressure at the output port is equal to pressure in the hydraulic oil tank. 2. When the control lever is moved slightly, lever (1) is tilted, and push rod (2) and pusher (3) are pushed in.
COMPONENT OPERATION / Pilot Valve Pusher Stroke: Between A and B 1 2 3 4 5 6 Port T (Clearance of Part A: 0) （A） Port P Notch Part 7 Output Port 1 - Lever 2 - Push Rod 3 - Pusher 4 - Spring Guide T4GD-03-06-003 T4GD-03-06-002 5 - Balance Spring 6 - Return Spring T3-6-3 7- Spool
COMPONENT OPERATION / Pilot Valve During Metering or Pressure Decrease (Pusher Stroke: Between C and D) Full Stroke (Pusher Stroke: Between E and F) 1. When the control lever is further tilted, the ouput port is connected to port P via spool (7). 2. Pressure oil of port P flows into the output port through spool (7) and pressure at the output port is raised. 3. Pressure at the output port acts on surface B of spool (7) and tends to push spool (7) upward. 4.
COMPONENT OPERATION / Pilot Valve Pusher Stroke: Between C and D Pusher Stroke: Between E and F 3 5 (C) Port T 4 Notch Part Surface B Port P Port P 7 7 Output Port 3- Pusher 4- Spring Guide Output Port T4GD-03-06-004 5- T3-6-5 Balance Spring 7- Spool T4GD-03-06-005
COMPONENT OPERATION / Pilot Valve ELECTROMAGNETIC DETENT The coil for detent is installed at the push rod part of the pilot valve. 3. Adsorbed condition is retained until the coil assembly (10) is unexcited or until attraction is forcefully cancelled by operating the control lever to the other direction. 1. When one of the control levers is tilted, push rod (2) and plate (8) of the other are pushed upward by the spring force. 2.
COMPONENT OPERATION / Pilot Valve OUTLINE (JOYSTICK TYPE PILOT VALVE FOR FRONT ATTACHMENT) Port No.
COMPONENT OPERATION / Pilot Valve OPERATION At Neutral 1. At neutral, spool (7) completely blocks pressure oil of port P. The output port is connected to port T through the fine control hole on spool (7). Therefore, pressure at the output port is equal to pressure at port T. 2. If the control lever is slightly tilted, disc (1) is tilted, and push rod (2) and piston (3) are pushed in. Piston (3) pushes spring guide (4) and balance spring (5) downward, and moves downward. 3.
COMPONENT OPERATION / Pilot Valve At Neutral 1 2 3 4 5 6 Port T (A) Port P (Clearance of Part A: 0) Fine Control Hole 7 Output Port T4GB-03-05-009 12- Disc Push Rod 3 - Piston 4 - Spring Guide T4GB-03-05-010 56- T3-6-9 Balance Spring Return Spring 7 - Spool
COMPONENT OPERATION / Pilot Valve During Metering or Pressure Decrease Full Stroke 1. When the control lever is further tilted, the ouput port is connected to port P via the fine control hole on spool (7). 2. Pressure oil of port P flows into the output port through spool (7) and pressure at the output port is raised. 3. Pressure at the output port acts on spool (7) and tends to push spool (7) upward. 4.
COMPONENT OPERATION / Pilot Valve During Metering or Pressure Decrease Full Stroke 2 3 4 5 Fine Control Hole Port P Fine Control Hole Port P 7 7 Output Port Output Port T4GB-03-05-011 23- Push Rod Piston 45- Spring Guide Balance Spring T4GB-03-05-012 7- T3-6-11 Spool
COMPONENT OPERATION / Pilot Valve ELECTROMAGNETIC DETENT The coil for detent is installed at the push rod part of the pilot valve. 3. Adsorption condition is retained until coil assembly (8) is unexcited or until attraction is forcefully cancelled by operating the control lever to the other direction. 1. When one of the control levers is tilted, push rod (2) and plate (9) of the other are pushed upward by the spring force. 2.
COMPONENT OPERATION / Pilot Valve OUTLINE (TWO-DERECTIONAL LEVER TYPE PILOT VALVE FOR ADDITIONAL CIRCUIT) (OPTIONAL) Port No.
COMPONENT OPERATION / Pilot Valve OPERATION At Neutral (Pusher Stroke: Between A and B) 1. At the neutral position of the control lever, spool (7) completely blocks pressure oil of port P. As the outlet port is connected to port T through the notch part of spool (7), pressure at the output port is equal to pressure in the hydraulic oil tank. 2. When the control lever is moved slightly, cam (1) is tilted, and pusher (2) and spring guide (4) are pushed in.
COMPONENT OPERATION / Pilot Valve Pusher Stroke: Between A and B 1 2 3 4 5 Port T 6 (A) Clearance of Part A: 0 Port P Hole Part 7 Passage T1LA-03-04-002 Output Port T1LA-03-04-003 Pusher Stroke: Between C and D 5 Port T Notch Part (B) Port P Hole Part 7 Output Port 1 - Cam 2 - Pusher 3 - Plate 4 - Spring Guide T1LA-03-04-004 56- T3-6-15 Balance Spring Return Spring 7 - Spool
COMPONENT OPERATION / Pilot Valve (Blank) T3-6-16
COMPONENT OPERATION / Pilot Valve OUTLINE (JOYSTICK TYPE PILOT VALVE FOR ADDITIONAL CIRCUIT) (OPTIONAL) Port No.
COMPONENT OPERATION / Pilot Valve OPERATION The head of spool (6) is supported by the top surface of spring guide (3). Spring guide (3) is lifted up by return spring (5). At Neutral (Output Diagram: Between A and B): 1. At neutral, spool (6) completely blocks pressure oil of port P (from the pilot pump). As the output port is connected to port T (to the hydraulic oil tank) through the internal passage of spool (6). 2.
COMPONENT OPERATION / Pilot Valve 1 1 2 2 3 3 4 4 5 5 6 7 Port P 6 6 Output Port Port T Port T 7 1 - Cam 2 - Pusher 7 Port P Output Port 3 - Spring Guide 4 - Balance Spring Port T Port P Output Port T1V1-03-04-007 5 - Return Spring 6 - Spool T3-6-19 T1V1-03-04-008 7 - Hole Part
COMPONENT OPERATION / Pilot Valve During Metering or Pressure Decrease (Output Diagram: Between C and D) 1. When the control lever is further tilted and pusher (2) is pushed down, hole part (7) on spool (6) reaches port P and pressure oil of port P flows into the output port. 2. Pressure at the output port acts on the bottom of spool (6) and tends to push spool (6) upward. 3. In case the force acting on spool (6) is smaller than the spring force of balance spring (4), balance spring (4) is not compressed.
COMPONENT OPERATION / Pilot Valve 1 1 2 2 3 3 4 4 5 5 6 6 Port T 7 Port P 7 Output Port 1 - Cam 2 - Pusher Port T 3 - Spring Guide 4 - Balance Spring Port P Output Port T1V1-03-04-009 5 - Return Spring 6 - Spool T3-6-21 7 - Hole Part T1V1-03-04-010
COMPONENT OPERATION / Pilot Valve Full Stroke (Output Diagram: Between E and F) 1. When the control lever is fully stroked, pusher (2) moves downward until it contacts the shoulder part of the casing. 2. At this time, spool (6) is directly pushed by the bottom of pusher (2). Therefore, although pressure at the output port is raised, hole part (7) on spool (6) is not closed. 3. Consequently, pressure at the output port side is equal to pressure at port P.
COMPONENT OPERATION / Pilot Valve 1 2 2 3 4 5 E 6 Port T 7 Port P Output Port 1 - Cam 2 - Pusher 3 - Spring Guide 4 - Balance Spring T1V1-03-04-011 T1V1-03-04-007 5 - Return Spring 6 - Spool T3-6-23 7 - Hole Part
COMPONENT OPERATION / Pilot Valve (Blank) T3-6-24
COMPONENT OPERATION / Charging Block OUTLINE The charging block is installed in order to supply pressure oil from the pilot pump not only to the service brake accumulator and the brake valve by giving them priority, but also to the parking brake and the steering pilot valve. The charging block consists of the priority valve, relief valve, pump torque control proportional solenoid valve, pilot relief valve and check valve.
COMPONENT OPERATION / Charging Block Layout 1 2 3 4 5 6 7 8 22 9 10 11 21 12 13 17 14 20 15 16 18 T4GD-03-07-001 4 1 - Service Brake Accumulator (Front) 2 - Adaptor 3 - Port M2 (To Front Side of Brake Valve) 4 - Check Valve 5 - Port M1 (To Rear Side of Brake Valve) 6 - Service Brake Accumulator (Rear) 7 - Service Brake Pressure Sensor 8 - Port P (from Pilot Pump) 19 9 - Priority Valve 16 - Port BR3 (To Parking Brake) 10 - Pilot Relief Valve 17 - Port PS2 (To Main Pump Regulator and Rid
COMPONENT OPERATION / Charging Block 11 * Section V-V 10 * Section U-U 14 12 21 * Section T-T 15 16 20 19 * Section S-S 18 4 4 *: Refer to T3-7-1.
COMPONENT OPERATION / Charging Block Layout 1 2 3 4 5 6 7 8 22 9 10 11 21 12 13 17 14 20 15 16 18 T4GD-03-07-001 4 1- Service Brake Accumulator (Front) 2 - Adaptor 10 - Pilot Relief Valve 3- 11 - Port DR (To Hydraulic Oil Tank) 45678- Port M2 (To Front Side of Brake Valve) Check Valve Port M1 (To Rear Side of Brake Valve) Service Brake Accumulator (Rear) Service Brake Pressure Sensor Port P (from Pilot Pump) 9- 19 Priority Valve 12 - Port DR2 (To Hydraulic Oil Tank) 13 - Port PS1 (
COMPONENT OPERATION / Charging Block Section Z-Z * 6 1 4 * 7 Section Y-Y 8 * Section X-X 4 Section W-W * 22 9 *: Refer to T3-7-1.
COMPONENT OPERATION / Charging Block PRIORITY VALVE (REFER TO THE PILOT CURCUIT IN THE SYSTEM / HYDRAULIC SYSTEM GROUP.) 1. Pressure oil from the pilot pump flows through port P and acts on the both ends of the plunger in the priority valve. 2. As same pressure acts on the both ends of the plunger, the plunger does not move and a restricted amount of pressure oil is supplied to other pilot circuits. 3.
COMPONENT OPERATION / Charging Block PILOT RELIEF VALVE 1. The pilot relief valve prevents pressure in the pilot circuit from increasing over the set pressure during operations of the actuators like the pilot valve. 2. When the pilot circuit pressure is more than the set pressure, pressure oil acts on the poppet in the pilot relief valve. 3. The poppet moves toward the spring and is connected to port DR. 4. Pressure oil in the pilot circuit returns to the hydraulic oil tank through port DR. 5.
COMPONENT OPERATION / Charging Block PUMP TORQUE CONTROL PROPORTIONAL SOLENOID VALVE (REFER TO THE PILOT CURCUIT IN THE SYSTEM / HYDRAULIC SYSTEM GROUP.) Pilot pressure supplied to the main pump regulator for the pump delivery flow rate control is controlled by the operation of the pump torque control proportional solenoid valve. Not in Operation of Solenoid Valve To Main Pump Regulator Port X 1. When there is no signal from MC (Main Controller), the spool of the solenoid valve is pushed by the spring. 2.
COMPONENT OPERATION / Charging Block SERVICE BRAKE ACCUMULATOR / PILOT ACCUMULATOR The accumulator is installed in the pilot circuit to the service brake and the pilot valve. High-pressure nitrogen gas is contained in the accumulator. Pilot pressure oil compresses nitrogen gas via the diaphragm. Pressure oil in the circuit is retained by compressing nitrogen gas. IMPORTANT: The accumulator cannot be disassembled. Replace the accumulator as an assembly if necessary.
COMPONENT OPERATION / Charging Block PARKING BRAKE SOLENOID VALVE Pressure oil from the pilot pump is accumulated in the pilot accumulator and its pressure always acts on the inlet of the parking brake solenoid valve. When the parking brake solenoid valve is operated, pressure oil in the pilot accumulator flows to the parking brake through the spool and releases the parking brake.
COMPONENT OPERATION / Charging Block Not in Operation Parking Brake Pressure Sensor Parking Brake Drain Port Spool Spring Parking Brake Solenoid Valve (Section T-T) Pilot Accumulator Pressure T4GB-03-07-005 In Operation Parking Brake Pressure Sensor Parking Brake Spool Spring Parking Brake Solenoid Valve (Section T-T) Pilot Pressure Accumulator Pressure T3-7-11 T4GB-03-07-006
COMPONENT OPERATION / Charging Block SERVICE BRAKE PRESSURE SENSOR This sensor detects brake pressure necessary for the service brake. The sensor is installed in the service brake circuit of the charging block and detects oil pressure of the service brake accumulator. 1 - Ground 2 - Output 3 - Power Source (5V) 4 - Pressure Receiving Area (Diaphragm) 1 2 4 3 T4GB-03-06-012 PARKING BRAKE PRESSURE SENSOR This sensor detects brake pressure necessary for the parking brake.
COMPONENT OPERATION / Ride Control Valve OUTLINE (REFER TO THE CONTROL BY COMBINED OPERATION OF ELECTRICAL CIRCUTT AND HYDRAULIC CIRCUIT / THE SYSTEM / CONTROL SYSTEM GROUP.) The ride control valve makes the vehicle travel stably by absorbing the force generated in the lift arm cylinder traveling on rough ground. The ride control valve consists of the ride control solenoid valve, spool, charge-cut spool and overload relief valve.
COMPONENT OPERATION / Ride Control Valve Layout Lift Arm Cylinder Ride Control Accumulator 5 Ride Control Valve SP 3 Pi 1 4 B A 2 To Hydraulic Oil Tank T From Charging Block T4GB-03-08-002 1 - Ride Control Solenoid Valve 2 - Charge-Cut Spool 34- Overload Relief Valve Spool 5- T3-8-2 Draing Plug
COMPONENT OPERATION / Ride Control Valve * Section A Port Pi To Ride Control Accumulator 1 Port SP 3 Port B Port A Port T 2 4 T4GB-03-08-003 * Section B Port SP 5 Port T *: Refer to T3-8-1.
COMPONENT OPERATION / Ride Control Valve OPERATION 1. In neutral, port Pi and the ouput port are not connected via the spool. 2. When the signal from MC (Main Controller) enters the solenoid, the solenoid is excited. 3. As the solenoid pushes the spool with the force corresponding to the signal from MC, port Pi and the output port are connected and pilot pressure oil pushes the main spool. 4.
COMPONENT OPERATION / Ride Control Valve (Blank) T3-8-5
COMPONENT OPERATION / Ride Control Valve CHARGE-CUT SPOOL The charge-cut spool accumulates the operating pressure for the lift arm cylinder in the ride control accumulator, and shuts down the operating pressure from the lift arm cylinder when the ride control accumulator pressure is accumulated to the set pressure. 1. When the ride control is not operated, pressure oil at the lift arm cylinder bottom side flows to port X through port A and the orifice. 2.
COMPONENT OPERATION / Ride Control Valve When Accumulating Accumulator Pressure Orifice Spring Port A Spool Port X To Ride Control Accumulator Port Y Check Valve T4GB-03-08-007 After Accumulating Accumulator Pressure Sectional Area M Sectional Area N T3-8-7 T4GB-03-08-008
COMPONENT OPERATION / Ride Control Valve OVERLOAD RELIEF VALVE The overload relief valve is installed in order to prevent the hoses and the ride control accumulator from being damaged in case pressure in the bottom side circuit of the lift arm cylinder is suddenly raised by an external force or something during operation of the lift arm cylinder. Operation 1. Pressure at port HP acts on the pilot poppet via orifice A of the main poppet and orifice B of the seat. 2.
COMPONENT OPERATION / Ride Control Valve During Normal Operation: Make-Up Valve Sleeve Main Poppet Orifice A Orifice B Seat Passage A Spring B HP LP Spring Chamber Spring C Spring A Pilot Poppet T176-03-03-012 During Relief Operation: Sleeve Main Poppet Orifice A Orifice B Seat Passage A Spring B HP LP Spring Chamber Spring A T3-8-9 Pilot Poppet T176-03-03-013
COMPONENT OPERATION / Ride Control Valve RIDE CONTROL ACCUMULATOR The ride control accumulator is installed in the accumulation circuit of the ride control. High-pressure nitrogen gas is contained in the accumulator and pressure oil compresses nitrogen gas via the piston. Compression of nitrogen gas dampens shock of pressure oil due to pitching of the lift arm cylinder raise circuit. IMPORTANT: The ride control accumulator cannot be disassembled.
COMPONENT OPERATION / Ride Control Valve DRAIN PLUG The drain plug is provided for the ride control valve in order to return pressure oil in the ride control accumulator to the hydraulic oil tank for maintenance. If necessary, loosen the lock nut and the drain plug. Connect the accumulator port (port SP) to the tank port (port T). CAUTION: When the drain plug is loosened too much, the drain plug is removed from the valve body and oil may sprush out. Do not loosen the drain plug by 2 turns or more.
COMPONENT OPERATION / Ride Control Valve (Blank) T3-8-12
COMPONENT OPERATION / Drive Unit OUTLINE The drive unit consists of the transmission and the torque converter. The drive unit is connected to the engine. Output power from the engine is transmitted to the transmission through the engine flywheel and the torque converter. Torque Converter Transmission T3-9-1 T4GD-03-09-004 .
COMPONENT OPERATION / Drive Unit TORQUE CONVERTER The torque converter consists of the converter wheel assembly, pump drive device, turbine shaft, and others. In the converter wheel assembly, impeller wheel (7) and turbine wheel (3) are mutually opposed with stator wheel (4) installed between them and they are all contained in the case filled with oil.
COMPONENT OPERATION / Drive Unit 7 8 9 10 11 1 2 3 4 5 6 T4GD-03-09-018 1 - Cover Wheel 2 - Input Plate 3 - Turbine Wheel 4 - Stator Wheel 5 - Input Guide 6 - Stator Hub 7 - Impeller Wheel 8 - Impeller Hub 9 - Pump Drive Gear T3-9-3 10 - Guide Carrier 11 - Turbine Shaft
COMPONENT OPERATION / Drive Unit TRANSMISSION The transmission functions to transform the rotation speed and rotation direction of the output power transmitted from the torque converter. The transmission consists of four clutch shaft assemblies, the reverse gear, output shaft, parking brake, control valve, and others. The relief valve is installed at the inlet part of the hydraulic oil for the torque converter, and relieves oil more than required into the converter housing.
COMPONENT OPERATION / Drive Unit Front View of Transmission 4 1 A B 5 B C 2 6 C 7 3 T4GD-03-09-003 A 1 - Breather 2 - Control Valve 34- Oil Feed Port Charging Pump 56- T3-9-5 Rotation Sensor (A) Rotation Sensor (B) 7- Travel Speed Sensor
COMPONENT OPERATION / Drive Unit Rear View of Transmission 1 Ｄ D D 2 3 4 9 8 7 6 5 Section D-D 1 - Engine Speed Sensor 4 - Hose 2 - From Oil Cooler 5- To Oil Cooler 6- Converter Outlet Pressure Port 7 - Hydraulic Oil Temperature Sensor Mounting Port 3 - Suction Tube T3-9-6 T4GD-03-09-001 8- Relief Valve 9- Spring
COMPONENT OPERATION / Drive Unit Side View of Transmission 3 2 1 4 5 6 7 8 9 10 11 12 1 - Converter Inlet Pressure Port 2 - Regulator Valve 3 - Regulator Pressure Port T4GD-03-09-004 4 - Forward Clutch Pressure Port 5 - Reverse Clutch Pressure Port 6 - 1st Speed Clutch Pressure Port 7 - 2nd Speed Clutch Pressure Port 8 - 3rd Speed Clutch Pressure Port 9 - 4th Speed Clutch Pressure Port T3-9-7 10 - Parking Brake Pressure Port 11 - Parking Brake Release Pressure Inlet 12 - Strainer
COMPONENT OPERATION / Drive Unit Section of Transmission 1 14 2 3 4 Section B-B* 13 5 12 11 10 9 Section C-C* 15 1234- Charging Pump Pump Drive Shaft Forward Clutch Distributor Cap 5678- 16 Parking Brake Front Output Flange Output Shaft Drain Plug 7 8 910 11 12 - *Refer to T3-9-5 T3-9-8 6 Section A-A* Rear Output Flange 1st / 2nd Speed Clutch Distributor Cap Idler Shaft T4GD-03-09-002 13 14 15 16 - Torque Converter Reverse Clutch Distributor Cap 3rd / 4th Speed Clutch
COMPONENT OPERATION / Drive Unit Clutch Shaft The clutch shaft assemblies contain the clutch discs of the respective speed shifts, and transmit or stop power.
COMPONENT OPERATION / Drive Unit (Forward Clutch Shaft) T4GD-03-09-005 (Reverse Clutch Shaft) T4GD-03-09-006 T3-9-10
COMPONENT OPERATION / Drive Unit (1st / 2nd Speed Clutch Shaft) T4GD-03-09-007 (3rd / 4th Speed Clutch Shaft) T4GD-03-09-008 T3-9-11
COMPONENT OPERATION / Drive Unit Operation During Operation The clutch is operated by pressure oil from the transmission control valve. Pressure oil from the transmission control valve reaches the back of clutch piston (7) through the oil passage inside shaft (11). The oil passage is blocked as pressure oil pushes bleed valve (5) in clutch piston (7) toward disc (8). Therefore, clutch piston (7) is pushed toward disc (8).
COMPONENT OPERATION / Drive Unit During Operation 1 8 9 7 11 Detail A From Control Valve A T4GC-03-09-012 Not during Operation 1 9 3 8 7 5 11 Detail B B T4GC-03-09-013 1 - Hub Gear 3 - Return Spring 57- Bleed Valve Clutch Piston 89- T3-9-13 Disc Plate 11 - Shaft
COMPONENT OPERATION / Drive Unit Transmission of Power 1 2 Input Reverse Gear 4 Forward Clutch Reverse Clutch 5 3 9 1st / 2nd Speed Clutch 7 6 Idler Gear 8 3rd / 4th Speed Clutch 12 10 13 14 11 15 16 Output 1234- Input Gear Reverse Gear F-R Gear F Hub Gear 5678- F-R Gear R Hub Gear Idler Gear Idler Gear 910 11 12 - T3-9-14 T4GC-03-09-002 2nd Speed Hub Gear 1st Speed Hub Gear Low-Range Gear 4th Speed Hub Gear 13 14 15 16 - 3rd Speed Hub Gear High-Range Gear Output Gear Output Ge
COMPONENT OPERATION / Drive Unit 5 6 Reverse Clutch 2 1 4 Forward Clutch 8 10 3 11 7 1st / 2nd Speed Gear 9 16 15 14 12 13 T4GC-03-09-014 T3-9-15
COMPONENT OPERATION / Drive Unit Forward 1st Speed In addition, torque is transmitted from 1st hub gear (10) to low-range gear (11), and finally to output gear (16). In case of forward 1st speed, the forward clutch is connected to the 1st speed part of the 1st / 2nd speed clutch. The torque converter transmits torque to F hub gear (4) which is meshed with input gear (1). Torque from F hub gear (4) is transmitted to 1st speed hub gear (10) through F-R gear (3), idler gear (7) and idler gear (8).
COMPONENT OPERATION / Drive Unit 1 4 Forward Clutch 3 8 10 7 11 1st / 2nd Speed Clutch 16 T4GC-03-09-016 1 - Input Gear 3 - F−R Gear 47- F Hub Gear Idler Gear 8 - Idler Gear 10 - 1st Speed Hub Gear T3-9-17 11 - Low-Range Gear 16 - Output Gear
COMPONENT OPERATION / Drive Unit Forward 2nd Speed In case of forward 2nd speed, the forward clutch is connected to the 2nd speed part of the 1st / 2nd speed clutch. The torque converter transmits torque to F hub gear (4) which is meshed with input gear (1). Torque from F hub gear (4) is transmitted to 2nd speed hub gear (9) through F-R gear (3) and idler gear (7). In addition, torque is transmitted from 2nd speed hub gear (9) to low-range gear (11), and finally to output gear (16).
COMPONENT OPERATION / Drive Unit 1 4 Forward Clutch 3 7 11 1st / 2nd Speed Clutch 16 9 T4GC-03-09-018 1 - Input Gear 3 - F−R Gear 47- F Hub gear Idler Gear 9 - 2nd Speed Hub Gear 11 - Low-Range Gear T3-9-19 16 - Output Gear
COMPONENT OPERATION / Drive Unit Forward 3rd Speed In addition, torque is transmitted from 3rd speed hub gear (13) to high-range gear (14), and finally to output gear (15). In case of forward 3rd speed, the forward clutch is connected to the 3rd speed part of the 3rd / 4th speed clutch. The torque converter transmits torque to F hub gear (4) which is meshed with input gear (1). Torque from F hub gear (4) is transmitted to 3rd speed hub gear (13) through F-R gear (3) and idler gear (8).
COMPONENT OPERATION / Drive Unit 1 4 3 Forward Clutch 8 7 15 14 3rd / 4th Speed Clutch 13 T4GC-03-09-020 1 - Input Gear 3 - F−R Gear 47- F Hub Gear Idler Gear 8 - Idler Gear 13 - 3rd speed Hub Gear T3-9-21 14 - High-Range Gear 15 - Output Gear
COMPONENT OPERATION / Drive Unit Forward 4th Speed In case of forward 4th speed, the forward clutch is connected to the 4th speed part of 3rd / 4th speed clutch. The torque converter transmits torque to F hub gear (4) which is meshed with input gear (1). Torque from F hub gear (4) is transmitted to 4th speed hub gear (12) through F-R gear (3) and idler gear (7). In addition, torque is transmitted from 4th hub gear (12) to high-range gear (14), and finally to output gear (15).
COMPONENT OPERATION / Drive Unit 1 4 Forward Clutch 3 7 15 12 3rd / 4th Speed Clutch 14 T4GC-03-09-022 1 - Input Gear 3 - F−R Gear 47- F Hub Gear Idler Gear 12 - 4th Speed Hub Gear 14 - High-Range Gear T3-9-23 15 - Output Gear
COMPONENT OPERATION / Drive Unit Reverse 1st Speed In case of reverse 1st speed, the reverse clutch is connected to the 1st speed part of the 1st / 2nd speed clutch. The torque converter transmits torque to R hub gear (6) from reverse gear (2) which is meshed with input gear (1). Torque from R hub gear (6) is transmitted to 1st speed hub gear (10) through F-R gear (5), idler gear (7) and idler gear (8).
COMPONENT OPERATION / Drive Unit 5 Reverse Clutch 6 2 1 7 8 10 11 1st / 2nd Speed Clutch 16 T4GC-03-09-024 1 - Input Gear 2 - Reverse Gear 5 - F-R Gear 67- R Hub Gear Idler Gear 8 - Idler Gear 10 - 1st speed Hub Gear T3-9-25 11 - Low-Range Gear 16 - Output Gear
COMPONENT OPERATION / Drive Unit TRANSMISSION REGULATOR VALVE The transmission regulator valve controls pressure oil from the charging pump in order to be constant pressure, and supplies it to the transmission control valve for controlling the clutch. Pressure oil entering port P of the regulator valve from the charging pump passes the small hole of the regulator spool, and enters the back chamber of the spool.
COMPONENT OPERATION / Drive Unit Normal state Small Hole of Regulator Spool Back Chamber Regulator Spool Spring Output Port Port P T4GC-03-09-025 From Charging Pump Overflowing state Back Chamber Regulator Spool Spring To Transmission Control Valve From Charging Pump To Torque Converter T3-9-27 T4GC-03-09-026
COMPONENT OPERATION / Drive Unit TRANSMISSION CONTROL VALVE The transmission control valve supplies oil that is maintained at constant pressure by the regulator valve to each clutch. This changes vehicle travel direction and speed. The transmission control valve is composed of the valve body and the proportional solenoid valve for each clutch. It controls the clutch oil pressure by operating the shift lever, actuating each proportional solenoid valve, and moving the modulation spool of the valve body.
COMPONENT OPERATION / Drive Unit Control Valve 4th Speed Clutch 3rd Speed Clutch 2nd Speed Clutch 1st Speed Clutch Reverse Clutch Forward Clutch Filter Regulator Valve Clutch Lubrication Torque Converter Cooler Torque Converter Torque Converter Relief Valve Filter Charging Pump T4GD-03-09-009 T3-9-29
COMPONENT OPERATION / Drive Unit 10 9 8 7 6 5 4 T4GD-03-09-010 3 1 - Cover 2 - Valve Body 3 - Solenoid Body 1 2 4 - 4th Speed Proportional Solenoid Valve 5 - 3rd Speed Proportional Solenoid Valve 6 - 2nd Speed Proportional Solenoid Valve 7 - 1st Speed Proportional Solenoid Valve 8 - Reverse Proportional Solenoid Valve T3-9-30 9- Forward Proportional Solenoid Valve 10 - Filter
COMPONENT OPERATION / Drive Unit From Charging Pump 1 2 3 24 4 5 23 6 7 8 22 9 10 21 11 12 20 13 14 15 19 16 17 18 T4GD-03-09-011 1 - Solenoid Body 2 - Valve Body 7 - Reverse Emergency Travel Spool 8 - Reverse Modulation Spool 3 - Cover 9 - Reverse Modulation Spring 4 - Forward Emergency Travel Spool 5 - Forward Modulation Spool 10 - 1st Speed Modulation Spool 11 - 1st Speed Modulation Spring 12 - 2nd Speed Emergency Travel Spool 6 - Forward Modulation Spring 13 - 2nd Speed Modulation
COMPONENT OPERATION / Drive Unit Operation Modulation mechanism enables smoother gearshift by changing the pressure increase waveform or pressure decrease waveform of each clutch depending on the vehicle condition (engine speed, travel speed, and others). Vehicle condition is judged by analyzing the information (electric signal) sensed by the engine speed sensor, travel speed sensor and shift lever with the transmission controller.
COMPONENT OPERATION / Drive Unit In Neutral Pressure oil maintained at constant pressure by the regulator valve flows to the transmission control valve, and is divided into oil passage (a) to proportional solenoid valve (1) and oil passage (b) to modulation spool (2). Pressure oil does not flow from oil passage (a) to oil passage (c) as the electric signal to be transmitted from the controller to proportional solenoid valve (1) is stopped in neutral.
COMPONENT OPERATION / Drive Unit Clutch Connection from Neutral (Clutch Pressure Increase) • During Clutch Connection (Refer to Oil Pressure Waveform A on T3-9-32.) 2. In addition, pressure oil to oil passage (d) passes back chamber (f) of modulation spool (2), and is supplied to back chamber (g) of modulation spool (2).
COMPONENT OPERATION / Drive Unit • At End of Clutch Connection • During Shift Down Condition from Forward 2nd (Refer to Pressure Oil Waveform B on T3-9-32.) Speed to 1st Speed [at DSS] Finally, pressures in oil chamber (e) and oil chamber (g) become equal. Spring (3) is installed in oil chamber (g). As the force pushing leftward of oil chamber (e) is larger than the force pushing rightward of oil chamber (g) and spring (3) force, modulation spool (2) is pushed to the left end.
COMPONENT OPERATION / Drive Unit MANUAL SPOOL (EMERGENCY TRAVEL SPOOL) When the solenoid valve cannot be operated due to electric malfunction (e.g.: disconnection), the control valve is shifted to forward 2nd speed or reverse 2nd speed by manually operating this spool. This spool is used for self-traveling of the vehicle to the place for maintenance in an emergency or something. IMPORTANT: Before operating the manual spool, stop the engine.
COMPONENT OPERATION / Drive Unit From Charging Valve c 1 a Forward Clutch b 2 3 4 5 d Reverse Clutch f 2nd speed Clutch 6 7 e • When Operating of Manual Spool From Charging To Each Clutch Pump T4GD-03-09-012 1 - Modulation Spring 2 - Forward Modulation Spool 3- Forward Emergency Travel Spool 4 - Reverse Modulation Spool 5- Reverse Emergency Travel Spool 6 - 2nd Speed Emergency Travel Spool T3-9-37 7- 2nd Speed Modulation Spool
COMPONENT OPERATION / Drive Unit PROPORTIONAL SOLENOID VALVE The proportional solenoid valve is used as a pilot valve for the clutch oil pressure, and supplies pressure oil to the modulation spool by receiving the electric signal from the controller and by increasing or decreasing oil pressure. Operation • In Neutral: Spool (1) is pushed rightward by spring (2). Output port S is connected to tank port T.
COMPONENT OPERATION / Drive Unit S T P 1 2 3 a a T107-02-07-005 1 - Spool 2- Spring 3- T3-9-39 Solenoid
COMPONENT OPERATION / Drive Unit PARKING BRAKE The parking brake is a wet type multiplate disc brake. The brake is a negative type so that it is released only when the brake release pressure acts on the oil chamber in the brake piston. The parking brake is installed on 1st speed / 2nd speed shaft of the transmission through the disc hub.
COMPONENT OPERATION / Drive Unit 1 2 3 4 Parking Brake Release Pressure Oil Chamber 5 6 7 8 T4GD-03-09-016 1 - Brake Plate 2 - Brake Disc 3 - Brake Housing 4 - End Plate 5 - Brake Piston 6 - Spring • Operation 1 7 - Disc Hub 8 - Shaft • Release 2 2 To Charging Block From Charging Block Oil Chamber Oil Chamber 5 5 6 7 7 T4GD-03-09-017 T3-9-41 T4GD-03-09-017
COMPONENT OPERATION / Drive Unit (Blank) T3-9-42
COMPONENT OPERATION / Axle OUTLINE The axle consists of the differential, final drive, axle shaft and brake. Axle Shaft Final Drive Power from the transmission is transmitted to the front axle and the rear axle via the propeller shaft. Inside the axle, power is transmitted to the differential, divided into left and right, and drives the axle shaft and the wheels through the final drive.
COMPONENT OPERATION / Axle DIFFERENTIAL The differential enables the left and the right drive wheels to rotate at different rotating speeds in steering of the vehicle body or traveling on bumpy roads.
COMPONENT OPERATION / Axle Function • Purpose of Differential When the vehicle body is steered, as the inner wheel turns with a smaller radius, the outer wheel needs to rotate faster for smooth steering. Suppose driving the rear wheel by directly installing the gear to the propeller shaft with a shaft having no differential. In this case, the outer wheel and the inner wheel rotate the same amount.
COMPONENT OPERATION / Axle • Principle of Differential Operational principle of the differential is explained comparing it to the racks and the pinion gear in the drawing. When load W is equally applied to racks A and B, if C is moved upward by the distance of H, racks A and B move by the same distance of H in unison with the pinion together. If moved by removing the load to rack B, the pinion rotates on rack A (with load applied) and moves rack B upward.
COMPONENT OPERATION / Axle In Steering When the vehicle body is turned, uneven resistances are applied to the drive wheels. Therefore, due to the difference of the resistances applied to the inner and outer wheels, differential pinion gears (1, 4) start revolving on side gears (2, 3), while rotating round the pinion shaft. Consequently, in case the resistance force applied to shaft (7) is large, pinion gears (1, 4) rotate in the same direction as the rotational direction on side gear (2) of shaft (7).
COMPONENT OPERATION / Axle TORQUE PROPORTIONING DIFFERENTIAL (TPD) The wheel loader is operated mostly on rough ground condition. Working efficiency and tire lives are lowered due to tire slippage. In order to avoid lowering of working efficiency and tire lives, the axle is provided with the torque proportioning differential. The differential pinion gear of the torque proportioning differential has an odd number of teeth, and the differential pinion gear and the side gear have special tooth profiles.
COMPONENT OPERATION / Axle Traveling Straight with the Same Resistances to Left and Right Tires In case resistances to the left and right tires are the same, distances ‘a’ and ‘b’ from the differential pinion gear center to the respective contact points of the left and right side gears are the same. Therefore, as the differential pinion gear and the left and right side gears solidly rotate forward, the driving forces of the left and right tires become the same.
COMPONENT OPERATION / Axle LIMITED SLIP DIFFERENTIAL (LSD) (OPTIONAL) Operational Principle The wheel loader must be operated on slippery ground condition like sand and muddy soil. In places like these, the tires can slip although the torque proportioning differential (TPD) is installed. As rotation is transmitted to the slipping tire and not to the tires contacting the road, not only the funtion of the wheel loader is worsened but the tire lives are shortened.
COMPONENT OPERATION / Axle Traveling Straight with the Same Road Resistances to Left and Right Tires As the differential pinion gear and the left and right pinion gears rotate solidly, the driving forces of the left and right tires are the same similarly to TPD. Traveling on Soft Ground (Different Road Resistances to Left and Right Tires) Driving force is transmitted to the case, pressure ring and spider through the ring gear.
COMPONENT OPERATION / Axle SERVICE BRAKE The brake is the wet type multi-disc brake and is assembled in the differential gear body of the axle. Four wheels of this vehicle has the disc brake respectively. • In Operation of Brake Oil pressure from the brake valve acts on the back of brake piston (5) and moves brake piston (5). Brake disc (3) and brake ring (2) are compressed. The inner surface of brake disc (3) is fitted to gear & shaft (7).
COMPONENT OPERATION / Axle 1 2 2 3 3 2 Brake Oil Pressure 4 5 6 7 T4GD-03-10-004 1 - End Plate 2 - Brake Ring 34- Brake Disc Differential Gear Body • In Operation 1 2 3 56- Brake Piston Return Spring 7- Gear & Shaft • In Release 2 3 From 2 Brake Valve 1 5 2 3 2 3 To 2 Brake Valve 5 6 6 T4GD-03-10-005 T3-10-11 T4GD-03-10-005
COMPONENT OPERATION / Axle FINAL DRIVE / AXLE SHAFT The final drive is the device finally to reduce the speed in the power transmission system, and is a planetary gear type. As for power transmission, power from the differential, is transmitted from the shaft, rotates three planetary gears in the ring gear, and transmits rotation of the planetary gear to the axle shaft through the planetary carrier.
COMPONENT OPERATION / Brake Valve OUTLINE The brake valve is operated by the brake pedal. (Refer to the Brake Circuit in the SYSTEM/Hydraulic System group) The brake valve delivers pilot pressure in response to the depressing stroke of the brake pedal and operates the front or rear wheel service brake.
COMPONENT OPERATION / Brake Valve Layout 1 2 3 4 Port T 5 6 Port BR1 Port M2 11 7 Port BR2 Port M1 10 8 9 T4GB-03-11-002 1 - Pedal 2 - Roller 3 - Spool Input 4 - Spring 5 - Spring 6 - Spring 7 - Spool 8 - Spool 9 - Spring T3-11-2 10 - Plunger 11 - Plunger
COMPONENT OPERATION / Brake Valve 1 5 7 From Port M2 of Charging Block M2 From Port M1 of Charging Block M1 BR1 BR2 T To Front Service Brake To Rear Service Brake 8 9 T4GB-03-11-003 T3-11-3
COMPONENT OPERATION / Brake Valve OPERATION Not in Operation of Brake 1. When the brake valve is not operated, ports (BR1, BR2) are connected to tank port (T) as spring (9) returns spools (7, 8) to the non-operating position. 2. As ports (M1, M2) and brake ports (BR1, BR2) are blocked by spools (7, 8), pressure oil in the service brake accumulator is retained.
COMPONENT OPERATION / Brake Valve When Brake is Applied 1. When the brake pedal is depressed, spool input (3) is pushed via roller (2). Spool input (3) moves spools (7, 8) forward via spring (5). 2. When spools (7, 8) are moved forward, ports (BR1, BR2) and port (T) are disconnected. When spools (7, 8) are further moved forward, ports (BR1, BR2) and ports (M1, M2) are connected, and pressure oil in the accumulator flows from ports (BR1, BR2) and the brake is applied. 3.
COMPONENT OPERATION / Brake Valve When Brake is Released 1. When the operating force of the brake pedal is released, spool input (3) is pushed back by spring (4). 2. Compression of spring (5) is released, and spools (7, 8) are returned to the non-operation position by summation of the hydraulic reaction force acting on the plunger and the load of spring (9). 3. At this time, ports (BR1, BR2) and ports (M1, M2) are blocked by spools (7, 8), and ports (BR1, BR2) are connected to the port (T).
COMPONENT OPERATION / Others PILOT SHUT-OFF VALVE The pilot shut-off valve is a munually operated selection valve, and by operating the pilot shut-off lever, rotates the spool in order to turn ON and OFF pilot pressure oil to the pilot valve. Section Z-Z When Pilot Shut-Off Lever is in LOCK Position When the pilot shut-off valve is turned OFF, pressure oil from the pilot pump does not flow to the pilot valve. Pressure oil at the pilot valve side flows to the hydraulic oil tank.
COMPONENT OPERATION / Others PROPELLER SHAFT The propeller shafts are installed between transmission and the front axle, and between transmission and the rear axle respectively. The propeller shaft transmits the power from transmission to the front axle and the rear axle. universal joint most commonly used is provided.
COMPONENT OPERATION / Others EMERGENCY STEERING CHECK BLOCK A: from main pump B: from emergency steering pump C: pressure sensor mounting port D: to steering valve E: to hydraulic oil tank The emergency steering check block is installed between the main pump and the steering valve. The built-in check valve prevents delivery oil from the emergency steering pump from flowing to the main pump.
COMPONENT OPERATION / Others EMERGENCY STEERING PUMP (OPTIONAL) The emergency steering pump is available in case supply of pressure oil from the main pump is suddenly stopped, and delivers pressure oil to the steering valve in place of the main pump until the vehicle body is moved to a safe place. The emergency steering pump consists of the gear pump, the electric motor, the relief valve and the check valve.
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