Toro 22-14OE02, 32-10BE03, 32-12OE03, 42-16BE01, 72041 Service Manual

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EATON 751, 781 HYDROSATIC TRANSAXLE

Table Of Contents – Page 1 of 1

751, 851, 771, AND 781 HYDROSTATIC T RANSAX LE

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 REASSE MB L Y TRANSAXLE WITH DUMP VALVE TRANSAXLE WITH CHARGE PUMP TRANSAXLE WITH CHARGE PUMP COVER REASSEMBLY TRANSAXLE WITH CHARGE PUMP AXLE HOUSING REASSEMBLY 781 SERIES TRANSAXLE TRANSAXLE WITH CHARGE PUMP AND SPI N- ON FILT ER FLUID RECOMMENDATIONS TRANSAXLE PART S LISTS FAULT-LOGIC TROUBLE SHOOTING DIAGRAM ACTION STEP COMMENTS

NO.

7-416

Eaton Hydraulics Division

751 851 771

and

781

Hydrostatic Transaxle

The following repair information applies to

the Eaton

751,851,771,

and

781

series hydro-

static transaxles.

Date

and Input Rotation Stamped on

Assembly Date Part Number Input Rotation Build Code

Customer Part Number (

Required

Original Build Factory Rebuild

example

01 01 91 01 01 91 11

The transaxle identification information is

010191

Month Day

(CW or CCW)

)

Year Number

this Surface

(

example

XXXXXX Factory

01/01/91 11

Month

Assembly,

)

Rebuilt

Rebuild

Code

Times

located opposite the input shaft, on the back

of the housing assembly.

The build code of the transaxles identifies

the month, day and year of the transaxle

manufacture. This information is found in the

same area as the identification code.

When ordering replacement parts for a transaxle, the part(s) order must include the part name, part number, quantity of parts and also the transaxle model number, input rotation and date code.

Transaxles 751,851,771, and 781

The following procedures describe complete and disassembly and reassembly of the transaxle. The level of cleanliness maintained while servicing the transaxle could affect its perfor-

(2)

mance. Work in a clean area. After disassembly, wash all parts with clean solvent and blow the parts dry with air. Inspect all mating surfaces. Replace any damaged parts that could cause internal leakage.

not use grit paper,

files or grinders on finished parts.

Note:

Whenever a transaxle is disassembled, our recommendation is to replace all seals. Lubricate the new seals with petroleum jelly before installation. Use only clean, recommended hydraulic fluid on the finished surfaces at reassembly.

The following tools are required for disas-

sembly and reassembly of the transaxle.

3/8

in. Socket or End Wrench

Ratchet Wrench

Torque Wrench

5/32

Hex Wrench

Small screwdriver

[150

N-m) long)

300

Ib-in

[102

[34

N-m)

N-m) to 6 in.

No. 5 or 7 Internal Retaining Ring Pliers

No.

or 5 External Retaining Ring Pliers

in.

[150

N-m) or 8 In.

[200

mm C-clamp

Piece of Pipe or Hydraulic Tubing

in.

O.D.

x 6 inches long)

Piece of Pipe or Hydraulic Tubing

(1-1/8

in.

[29

mm] O.D.

in.

[150

mm] long)

Small Arbor or Hydraulic Press

or 4 Large Rubber Bands

Light Petroleum Jelly (such as Vaseline)

Seal all open ports before cleaning. Thor-

oughly clean the transaxle exterior.

After draining the transaxle, use your

hand or a filter wrench to remove the filter

from the filter base.

Note:

It is best to drain the transaxle through the case drain port with the input shaft in the down position.

Plugs and Fittings

781

Series Hydrostatic Transaxle

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. Remove the two conical springs. Safely store these small parts for final assembly after servicing each transaxle half. Each half has a flange attached with eight

.25

Torx

But.

Head

screws. These screws have been secured with Loctite ( torque ref.-

[14 +1,4

Nm]), flange removal is not recom-

125 f12.5

Ib-in

mended. Service each half separately as outlined in the following text.

Port Plate (Horizontal

Valve Cover

(Vertical Mount)

Port Plate (for Remote Filter)

“U”

Filter

Base

Mount)

Hex.

Hex. Flange Screw

Adapter,718-14O-ring Seal, Square Cut

Flange Screw

(Qty.

Port

Filter (Internal)

asket

Using a

3/8

inch socket or end wrench,

remove the cap screws from

filter base. valve cover and internal filter. port plate.

Remove gasket.

Note:

This gasket may be on the part just

removed or on the housing assembly.

Spin -on Filter Cartridge

Clean

Bench C-Clamp

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 from possible damage during repositioning. Use a 6 inch

[I50

mm] to 8 inch

[200

mm] C-clamp to secure the transaxle to a suitable work surface. Be careful not to over tighten the

C-

clamp when securing the transaxle.

To disassemble the axle housing assembly, carefully position the axle housing assembly on a clean flat surface, then separate axle housing from the planetary assemblies as shown.

Axle Housing Retaining

Axle

Shaft

with One Retaining Ring

Axle

Housing Disassembly

With the transaxle secure, use a

3/8

inch socket or end wrench to remove the flange screws from one (A-side or B-side) axle housing assembly.

After removing the flange screws, carefully remove the axle housing assembly from the housing assembly.

Caution:

Retain the planetary assemblies in

the axle housing assembly during removal.

Position the axle housing assembly with the output end of the axle shaft in the up position. Using a

No.

or 7 internal retaining ring pliers, remove the ball bearing retaining ring from the axle housing.

Re-position the axle housing with the

splined end of the axle in the up position.

Using a

No.

or 5 external retaining ring pliers, remove the retaining ring and thrust washer from the axle shaft.

Remove the axle from the axle housing by using a small press or by tapping the splined end of the axle shaft with a plastic head hammer. This will dislodge the seal and bearing

from the axle housing.

After separating the axle shaft from the

axle housing, remove the ball bearing, seal

and thrust washer from the axle shaft. The thrust washer may be in the axle housing.

Note:

The retaining ring remaining on the axle

shaft need not be removed.

Ring Gear

Sun

Gear, Second

Ring Gear

Primary Carrier

Planet Gears, First

To disassemble the planetary assemblies

for inspection and cleaning, first remove the

ring gear (from the secondary carrier/ planet

gears).

Next, putting a slight squeeze on the secondary carrier planet gears, remove the three secondary planet gears, and carrier.

Turn the assembly over and remove the secondary planet gears for inspection and cleaning.

Remove the sun gear and remaining ring gear.

Again, putting a slight squeeze on the

remaining carrier planet gears, remove planet

gears, and carrier from the backup plate.

Shown above are both the primary and secondary carrier assemblies. The planet gears may be removed for inspection and cleaning.

Backup Plate

Sun Gear (First)

Next, remove the reaction plate from the

primary sun gear.

Remove the primary sun gear from the

motor rotor assembly.

Remove the small friction brake pad assembly from its recessed pocket located in the axle housing.

Shown in previous drawing are the three major parts used in the Eaton transaxle wet brake assembly, the friction pad assembly, reaction plate and backup plate. When the brake is applied, the rotating reaction plate is squeezed between the stationary friction pad and the backup plate.

Remove the axle housing assembly gas-

ket.

Note:

This gasket may have remained on the

axle housing.

Normally any further disassembly of the brake levers, push rods and etc. is not necessary nor recommended. The brake lever shims located between the two brake levers is

used to adjust the brake lever movement. This adjustment was made during the initial transaxle assembly.

Note:

Standard single handle brake arrange-

ment shown.

Motor Rotor Disassembly 32 Important: Be extremely careful when

removing the motor rotor assembly. The ball pistons are spring loaded in the bores and must remain intact because each ball piston is matched to its respective bore.

The best way to remove the motor rotor assembly is to place a separate motor race on top of the existing motor race in the housing assembly. Hold the separate race securely in position. Then carefully pull the motor rotor assembly outward until the ball pistons are fully engaged in the groove located in the center of the separate race. Carefully remove the rotor assembly and race together as a set,

handling the motor rotor assembly only.

Note:

a separate motor race is not available, work a wide rubber band around the outside of the motor rotor to hold the ball pistons in their bores. 33

It is essential that the ball pistons be re-

tained in their bores during handling. This is

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