7-416 P/L 01-02 - Eaton

1 October, 1991 Eaton Hydrostatic Transaxle751, 851, 771, and 781 TransaxleRepair InformationA2 Note: It is best to drain the transaxle throughthe case drain port with the input shaft in thedown with Charge Pump 8 After draining the transaxle, use yourhand or a filter wrench to remove the filterfrom the filter base. 1 The following repair information applies tothe Eaton 751, 851,771, and 781 series hydro-static Number, Date of Assembly,and Input Rotation Stamped onthis SurfaceXXX-XXX XXX XXXXXXXXXXXX XX/XX/XX 11 AssemblyPart NumberInput Rotation(CW or CCW)CustomerPart Number( if Required )FactoryRebuildCodeOriginal Build( example - 010191 )010191 YearDayMonthFactory Rebuild( example - 01/01/91 11 )010191 YearDayMonth11 Number ofTimesRebuilt (2)Date ofBuild Code 2 The transaxle identification information islocated opposite the input shaft, on the backof the housing assembly.

2 3 The build code of the transaxles identifiesthe month, day and year of the transaxlemanufacture. This information is found in thesame area as the identification code. 4 When ordering replacement parts for atransaxle, the part(s) order must include thepart name, part number, quantity of parts andalso the transaxle model number, input rota-tion and date 751, 851, 771, and 781 5 The following procedures describe com-plete and disassembly and reassembly of level of cleanliness maintained whileservicing the transaxle could affect its perfor-mance. Work in a clean area. After disassem-bly, wash all parts with clean solvent and blowthe parts dry with air. Inspect all mating sur-faces. Replace any damaged parts that couldcause internal leakage. Do not use grit paper,files or grinders on finished : Whenever a transaxle is disassembled,our recommendation is to replace all the new seals with petroleum jellybefore installation.

3 Use only clean, recom-mended hydraulic fluid on the finished sur-faces at reassembly. 6 The following tools are required for disas-sembly and reassembly of the transaxle. 3/8 in. Socket or End Wrench 1 in. Socket or End Wrench Ratchet Wrench Torque Wrench 300 lb-in [34 Nm] 5/32 Hex Wrench Small screwdriver (4 in [102 mm] to 6 in.[150 mm] long) No. 5 or 7 Internal Retaining Ring Pliers No. 4 or 5 External Retaining Ring Pliers 6 in. [150 mm] or 8 In. [200 mm] C-clamp Piece of Pipe or Hydraulic Tubing(1 in. x 6 inches long) Piece of Pipe or Hydraulic Tubing(1-1/8 in. [29 mm] x 6 in. [150 mm] long) Small Arbor or Hydraulic Press 3 or 4 Large Rubber Bands Light Petroleum Jelly (such as Vaseline) 7 Seal all open ports before cleaning. Thor-oughly clean the transaxle Plate(Horizontal Mount)Plugs andFittingsValve Cover(Vertical Mount)Port Plate(for Remote Filter)Spin -on Filter Cartridge L Filter BaseSpin -onFilterCartridgeGasketGasketGasketGask etGasketFilter (Internal)Adapter, 7/8-14 O-ring PortSeal, Square Cut U Filter BaseHex.

4 Flange Screw(Qty. 5)Hex. Flange Screw(Qty. 5)Hex. Flange Screw(Qty. 3)(Qty. 2)Hex. Flange Screw(Qty. 4)(Qty. 1)10 Using a 3/8 inch socket or end wrench,remove the cap screws from .. filter valve cover and internal port plate. 11 Remove : This gasket may be on the part justremoved or on the housing RodConical Springand E-RingConicalSpringand E-RingNut andWasher (5)Hex. HeadCap Screw(5)FlangeFlange781 Series781 Series Hydrostatic Transaxle 9 Divide the transaxle halves by removingonly one E-ring retaining the conical springon each end of the center brake push rod,then remove four 1/2 inch hex. nuts, thelock washers and bolts. Pull the two halvesapart carefully, the push rod is the onlyadjoining link. Remove the two conicalsprings. Safely store these small parts forfinal assembly after servicing eachtransaxle half.

5 Each half has a flangeattached with eight .25 Torx But. Headscrews. These screws have been securedwith Loctite ( torque ref. 125 lb-in[14 1,4 Nm]), flange removal is not recom-mended. Service each half separately asoutlined in the following Position the axle housing assembly withthe output end of the axle shaft in the upposition. Using a No. 5 or 7 internal retainingring pliers, remove the ball bearing retainingring from the axle Re-position the axle housing with thesplined end of the axle in the up a No. 4 or 5 external retaining ringpliers, remove the retaining ring and thrustwasher from the axle Remove the axle from the axle housing byusing a small press or by tapping the splinedend of the axle shaft with a plastic head ham-mer. This will dislodge the seal and bearingfrom the axle After separating the axle shaft from theaxle housing, remove the ball bearing, sealand thrust washer from the axle shaft.

6 Thethrust washer may be in the axle : The retaining ring remaining on the axleshaft need not be To disassemble the axle housing assem-bly, carefully position the axle housing assem-bly on a clean flat surface, then separate axlehousing from the planetary assemblies Position transaxle with this gasket surfacetoward the bench. Place a clean towel be-tween the transaxle and the bench. This towelprotects the sealing surface from possibledamage during repositioning. Use a 6 inch[150 mm] to 8 inch [200 mm] C-clamp tosecure the transaxle to a suitable work sur-face. Be careful not to over tighten the C-clamp when securing the TowelC-ClampRetaining RingBearing, BallAxle Shaft with One Retaining RingAxle HousingRetainingRingThrustWasherThrust WasherRadial Lip SealAxle Housing (S/A)Planetary AssembliesAxle Housing Disassembly13 With the transaxle secure, use a 3/8 inchsocket or end wrench to remove the flangescrews from one (A-side or B-side) axle hous-ing After removing the flange screws, carefullyremove the axle housing assembly from thehousing : Retain the planetary assemblies inthe axle housing assembly during Housing (S/A) andPlanetary AssembliesHex.

7 FlangeScrews (8)Please Note Location ofthe Axle Housing MountingSurface, must be Assembled in theSame OrientationMounting Surface(Vertical Mount Model Shown)5 GasketFriction PadMotorRotor/Ball (S/A)with Rubber BandBall RetainerReactionPlateBackup PlateSun Gear (First)Ring GearRing GearSecondary CarrierPlanet Gears, SecondSun Gear, SecondPrimary CarrierPlanet Gears, First20 To disassemble the planetary assembliesfor inspection and cleaning, first remove thering gear (from the secondary carrier/ planetgears).21 Next, putting a slight squeeze on the sec-ondary carrier planet gears, remove the threesecondary planet gears, and Turn the assembly over and remove thesecondary planet gears for inspection Remove the sun gear and remaining Again, putting a slight squeeze on theremaining carrier planet gears, remove planetgears, and carrier from the backup Shown above are both the primary andsecondary carrier assemblies.

8 The planetgears may be removed for inspection Next, remove the reaction plate from theprimary sun Remove the primary sun gear from themotor rotor Remove the small friction brake pad as-sembly from its recessed pocket located in theaxle Shown in previous drawing are the threemajor parts used in the Eaton transaxle wetbrake assembly, the friction pad assembly,reaction plate and backup plate. When thebrake is applied, the rotating reaction plate issqueezed between the stationary friction padand the backup Remove the axle housing assembly : This gasket may have remained on theaxle Normally any further disassembly of thebrake levers, push rods and etc. is not neces-sary nor recommended. The brake levershims located between the two brake levers isused to adjust the brake lever movement.

9 Thisadjustment was made during the initialtransaxle : Standard single handle brake arrange-ment Rotor Disassembly32 Important: Be extremely careful whenremoving the motor rotor assembly. Theball pistons are spring loaded in the boresand must remain intact because each ballpiston is matched to its respective best way to remove the motor rotor as-sembly is to place a separate motor race ontop of the existing motor race in the housingassembly. Hold the separate race securely inposition. Then carefully pull the motor rotorassembly outward until the ball pistons arefully engaged in the groove located in thecenter of the separate race. Carefully removethe rotor assembly and race together as a set,handling the motor rotor assembly : If a separate motor race is not avail-able, work a wide rubber band around theoutside of the motor rotor to hold the ballpistons in their It is essential that the ball pistons be re-tained in their bores during handling.

10 This is6especially true for the motor rotor(s), as themotor ball pistons are spring loaded in : The remaining transaxle axle housingassembly, if applicable, can be serviced at thistime (ref. steps 12-34) .Retaining RingInput Shaft (S/A)Input Shaft SealButton (2)GasketCoverSelf TapScrew(13)Control Shaft Seal34 Reposition the housing assembly. Using a3/8 inch socket or end wrench, remove theself tap screws from the cover : One self tap screw is located in thecase drain With all self tap screws removed (13),carefully separate and remove the cover fromthe housing Turn the cover assembly over and removethe two : These two buttons may have droppedout into the housing assembly during removalof the Turn the cover assembly back over andusing a No. 5 or 7 internal retaining ring pliers,remove the input shaft retaining Reposition and support the cover allowingroom for shaft removal.