EATON 751, 781 HYDROSATIC TRANSAXLE Table Of Contents – Page 1 of 1 751, 851, 771, AND 781 HYDROSTATIC TRANSAXLE TRANSAXLES 751, 851 TRANSAXLE WITH CHARGE PUMP 781 SERIES HYDROSTATIC TRANSAXLE AXLE HOUSING DISASSEMBLY MOTOR ROTOR DISASSEMBLY TRANSAXLE WITH CHARGE PUMP PUMP AND MOTOR ROTOR INSPECTION TRANSAXLE WITH CHARGE PUMP TRANSAXLE WITH DUMP VALVE TRANSAXLE REASSEMBLY TRANSAXLE WITH DUMP VALVE TRANSAXLE WITH CHARGE PUMP TRANSAXLE WITH CHARGE PUMP COVER REASSEMBLY TRANSAXLE WITH CHARGE PUMP AXLE HOUSING
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1 The following repair information applies to the Eaton 751,851,771,and 781 series hydrostatic transaxles. Assembly Date Code Rotation Build Input Number Part CCW) \ or Customer Part Number ( if Required ) 01 91 Date of Assembly, and Input Rotation Stamped on this Surface of (CW \ XXXXXX Factory 11 Rebuild Factory Original Build example 010191 ) 01 01 Number Rebuild Code ( example 01/01/91 11 ) 91 11 of Times Rebuilt (2) Year Month Month 2 The transaxle identification information is located oppo
Plugs and Fittings Adapter,718-14O-ring Seal, Square Cut Port Port Plate (Horizontal Mount) Hex. Flange Screw (Q Filter (Internal) Valve Cover (Vertical Mount) asket Hex. Flange Screw (Qty. 5) 781 Series Hydrostatic Transaxle 9 Divide the transaxle halves by removing only one E-ring retaining the conical spring on each end of the center brake push rod, then remove four 1/2 inch hex. nuts, the lock washers and bolts. Pull the two halves apart carefully, the push rod is the only adjoining link.
Clean Bench C-Clamp 12 Position transaxle with this gasket surface toward the bench. Place a clean towel between the transaxle and the bench. This towel protects the sealing surface frompossible damage during repositioning. Use a 6 inch [I50mm] to 8 inch [200 mm] C-clamp to secure the transaxle to a suitable work surface. Be careful not to overtighten the Cclamp when securing the transaxle.
Gear Ring Sun Gear, Second Ring Gear Primary Carrier Planet Gears, First 20 To disassemble the planetary assemblies for inspection and cleaning, first remove the ring gear (from the secondary carrier/ planet gears). 21 Next, putting a slight squeeze on the secondary carrier planet gears,remove the three secondary planet gears,and carrier. 22 Turn the assembly over and remove the secondary planet gears for inspection and cleaning. 23 Remove the sun gearand remaining ring gear.
especially true for the motor rotor(s) as the motor ball pistons are spring loaded in the bores. Note: The remaining transaxle axle housing assembly, if applicable, can be serviced at this time (ref. steps 12-34) tool, pry the control shaft seal from the cover. 42 Remove the cover gasket fromthe housing. Note: The gasket may have remained on the cover. 43 Remove the drive from the pump rotor assembly. Drive Retaining Ring Control Shaft Seal \ Input Shaft (S/A) \ Control Shaft and Insert Pump Rotor/Bal
Motor Rotor/Ball ( S A ) Pump Rotor/Ball ( S A ) Pump and Motor Rotor Inspection 51 Disassemble and Inspect the rotor assembly in the following manner. Remove the piston balls from the rotor, one at a time, working clockwise from the letter stamped in the rotor face. Place the piston balls in a prepared container (use a container such as an egg carton or ice cube tray to hold the balls). Note: The balls must be replaced in the same bores from which they wereremoved because they are all select fit.
Transaxle Reassembly 63 Before reassembling the transaxle, clean all parts and assemblies with clean solvent and blow them drywith compressed air. Inspect and replace all scratched or damaged parts. Replace all gaskets, seals and seal rings. Lubricate all seals with petroleum jelly (Vaseline) for retention during assembly. Freely lubricate all bearings and finished part surfaces with clean hydraulic fluid to provide lubrication at start-up.
At assembly, this arrow must facetoward the input rotation designated in the housing. Note: High pressure charge pumpgerotor and plate is a matched set and is not sold separately. Class gerotor and plate are not a matched set. 75 Aligning the rotation arrow with the input rotation, install the pump plate over the gerotor. 76 Install the four cap screws in the pump plate finger tight. 77 The bottom side of the pump rotor assembly incorporates five drive pins.
Self Tap Screw screws (if used) and install the self tap screws (13), and alternately tighten to 125 Ib-in [14 Nm]. Torque each screw a second time to compensate for gasket compression set. Housing AxleRetaining Thrust Washer AxleShaftwithOneRetalnlngRing 92 Install the cover assembly by carefully aligning it with the control shaft, cam ring pivot dowel and pump rotor drive.
When they are all in alignment, the ring gear will fall into place.
on the housing assembly. 119 Install the axle housing flange screws and torque to 125 Ib-in [14Nm]. I Transaxle with Charge Pumpand Spinon Filter 124 Lubricate the filter seal, install filter, hand tight (3/4to 1 full turn after gasket/ base contact). 125 Fill transaxle with an approved hydraulic fluid ( 781 Series-both halves must be filled separately). The transaxle is now ready for test and installation.
Defective Fault-Logic Trouble Shooting This Fault Logic Troubleshooting Guideis designed as a diagnostic aid in locating possible transaxle problems by the user. To use this Fault-Logic Troubleshooting Guide, simply match the transaxle symptoms with the problem statements and followthe action steps shownin thebox diagrams. This will give the user unnecessary machine down time. Following the Fault-Logic diagrams are diagram action comments to further help explainthe action steps shown in the diagrams.
System Operating Hot Level Oil in Reservoir Cooling or Expansion Tank Inspect Transaxle Cooling Fins Ok Defe'ctive LOW Dump Valve ( if used ) Plugged Fill to Proper Level OK Defective I Repair Repair Clean Transaxle ( if Brake/Drive Ok Defective ) Interlock Linkage used Defective Repair Repair Replace System will not Hold orFree Wheels on Incline Dump Interlock Brake/Drive Valve ( if used ) e used ( if Linkage ) Transaxle Input Drive Defective Ok Replace Hubs Repair or Repla
r: Loss of Power or System (Will not operate in either direction) Check Oil Level in Reservoir or Expansion Tank inspect Wheel Defective Ok Dump Valve ( if used ) Defe'ctive Defective Defective Repair Repair Repair Fill to Proper Level Transaxle Ok Ok Brake/DriveInterlock External Linkage Inspect Control Ok Defective Repair Repair Repair Replace n Diagram Action Step Comments 1 Check oil Level in ReservoirorExpansionTank for: A Consult own/operators manual for the proper type fluid a
Eaton Corporation Hydraulics Division 15151 Highway 5, Eden Prairie, MN 55344 Telephone (612) 937-9800 EatonG.m.b.H. HydraulicsDivision 100 410 D-5620 Velbert 1 WestGermany 49-2051-2070 Printed in U.S.A. FORM NO.
