Service Manual Owner's manual
Table Of Contents
- Section 1. Specifications
- Section 2. General
- Section 3. Chassis & Turntable
- 3.1 Tires & Wheels
- 3.2 Wheel Drive Assembly, 2WD
- 3.3 Drive Motor - 2WD (Prior to S/N 83331)
- 3.4 Drive Motor (S/N 83331 to Present)
- 3.5 Torque Hub
- 3.6 Wheel Drive Assembly, 4WD
- 3.7 Torque Hub (4WD Machines W/ Integral Brake)
- Roll, Leak and Brake Testing
- Tightening and Torquing Bolts
- Main Disassembly
- Input Carrier Disassembly
- Output Carrier Disassembly
- Housing-Spindle Disassembly
- Spindle-Brake Disassembly
- Input Carrier Sub-Assembly
- Output Carrier Sub-Assembly
- Spindle-Brake Sub-Assembly
- Housing-Spindle Sub-Assembly
- DW2B Integral Brake Check
- Main Assembly
- 3.8 Drive Brake, 2WD - Mico (Prior to S/N 83331)
- 3.9 Re-Aligning torque hub input coupling
- 3.10 Oscillating Axle Bleeding Procedure and Lockout Test
- 3.11 Swing Drive Hub
- 3.12 Swing Brake - Mico (Prior to S/N 66417)
- 3.13 Swing Motor (Prior to S/N 66417)
- 3.14 Swing Motor (S/N 66417 to Present)
- 3.15 Procedure For Setting Gear Backlash
- 3.16 Swing Bearing
- 3.17 Rotary Coupling
- 3.18 Generator
- 3.19 Ford EFI Engine
- 3.20 Deutz EMR 2 (S/N 85332 to Present)
- 3.21 GM Engine General Maintenance
- 3.22 GM Engine Dual Fuel System
- Fuel Filter
- Electric Lock Off
- EPR Assembly
- Low Pressure Regulator (LPR)
- Air Fuel Mixer
- Electronic Throttle Control (ETC)
- Engine Control Module
- Heated Exhaust Gas Oxygen Sensor
- Gasoline Multi Point Fuel Injection System (MPFI)
- Gasoline Fuel Pump
- Gasoline Pressure And Temperature Sensor Manifold
- Fuel Filter
- Fuel Injector Rail
- Fuel Injector
- 3.23 GM Engine Fuel System Repair
- Propane Fuel System Pressure Relief
- Propane Fuel System Leak Test
- Propane Fuel Filter Replacement
- Electronic Pressure Regulator (EPR) Assembly Replacement
- Temperature Manifold Absolute Pressure (TMAP) Sensor
- Electronic Throttle Control Replacement
- Mixer Replacement
- Coolant Hose Replacement
- Vapor Hose Replacement
- Engine Control Module Replacement
- Heated Exhaust Gas Oxygen Sensor Replacement
- 3.24 GM Engine LPG Fuel System Diagnosis
- Section 4. Boom & Platform
- Section 5. Hydraulics
- Section 6. JLG Control System
- Section 7. Basic Electrical information & schematics
SECTION 4 - BOOM & PLATFORM
4-38 – JLG Lift – 3121139
4.8 HELAC ROTARY ACTUATOR
Theory of Operation
The rotary actuator is a simple mechanism that uses the
sliding spline operating concept to convert linear piston
motion into powerful shaft rotation. Each actuator is com-
posed of a housing with integrated gear teeth (01) and
only two moving parts: the central shaft with integrated
bearing tube and mounting flange (02), and the annular
piston sleeve (03). Helical spline teeth machined on the
shaft engage matching splines on the in-side diameter of
the piston. The outside diameter of the piston carries a
second set of splines, of opposite hand, which engage
with matching splines in the housing. As hydraulic pres-
sure is applied, the piston is displaced axially within the
housing -similar to the operation of a hydraulic cylinder
while the splines cause the shaft to rotate. When the con-
trol valve is closed, oil is trapped inside the actuator, pre-
venting piston movement and locking the shaft in position.
The shaft is supported radially by the large upper radial
bearing and the lower radial bearing. Axially, the shaft is
separated from the housing by the upper and lower thrust
washers. The end cap is adjusted for axial clearance and
locked in position by set screws or pins.
NOTE: Bars indicate starting positions of piston and shaft.
Arrows indicate direction they will rotate. The hous-
ing with integral ring gear remains stationary.
As fluid pressure is applied, the piston is displaced
axially while the helical gearing causes the piston
and shaft to rotate simultaneously. The double helix
design compounds rotation: shaft rotation is about
twice that of the piston.