Hydraulic 2/4 Wheel Drive Unit
(4WD Spring ON)
Dismantling and Assembly
Note: Before dismantling the unit drain the gearbox oil.
Dismantling
1 Hold the yoke E using service tool 892/00812 and undo
bolt F. Remove the yoke. Carefully remove and discard
oil seal M. Be sure not to damage the seal housing.
2 Undo bolts D. Lift off the 4WD casing P. Lift out the
4WD unit from the gearbox.
3 Remove bearing 1, only if to be renewed.
4 Remove seal ring 2. Note, If the piston ring seal is
damaged or excessively worn then check for burrs or
damage on the shaft groove. If necessary remove burrs
with a fine grade abrasion paper and oil.
5 Pull off the 4WD output gear 5, together with its bearing
3, needle roller bearing 6 and thrust washer 4.
6 Using a suitable press, compress disc springs 8A, 8B
and remove the circlip 7.
CAUTION: There is approximately 26700N (6000lbf)
clamping force acting on the springs.
7 Remove disc springs 8A, 8B, pressure plate 9, shim(s)
10 (keep the shim(s) separate from the counter plates),
and clutch pack friction plates and counter plates 11.
8 Remove the clutch drum retaining circlip 12 and
support washer 13.
9 Remove clutch drum 14 and actuating sleeve 15 .
10 Remove disc spring 16.
11 Remove the piston 17 and its spring steel ring 18.
12 Remove and discard piston O-rings 19 and 20.
13 Remove the piston housing 21 only if necessary, the
housing is a press fit on shaft 22.
Inspection
Carry out a visual inspection of the friction and counter
plates.
Counter plates - light scoring/polishing is permissible, plates
that are not flat, worn or heavily marked or scored must be
replaced with a new set.
Friction plates - the cross hatching should be clearly visible,
plates that are not flat, have friction material damage or
scoring must be replaced with a new set.
Do not mix old, new and worn plates.
Two different suppliers of the thinner friction plates (1.6 to
1.7 mm, 0.062 to 0.067 in approx) have been used (identify
as brown or green), do not mix the different plates in the
same clutch pack.
Assembly
Note: Use the pressure test adaptor and clamp assembly
(see Service tools) to ‘bench test’ the clutch. Bench testing
will ensure the clutch operates correctly prior to - assembling
and installing in the machine. Refer to Hydraulic 2/4 Wheel
Drive Unit, Pressure Testing the 2/4 WD Clutch.
1 Grease the shaft 22 then fit the piston housing 21 by
pressing the shaft squarely into the housing (make sure
the housing is securely supported on the centre boss).
2 Fit new O-rings 19 and 20 to piston 17, locate the
piston into housing 21. Fit spring steel ring 18 ensuring
that it seats firmly in its groove.
3 Place the disc spring 16 into the housing 21.
4 Position the actuating sleeve 15 onto the disc spring 16.
5 Install the clutch drum 14 in the housing. Fit support
washer 13 and drum securing circlip 12.
6 Build up the clutch pack 11, installing friction plates and
counter plates alternately, starting with a counterplate
and finishing with a friction plate.
7 Install shim(s) 10 and pressure plate 9.
8 Use the output gear 5 to align the clutch plate splines.
Ensure that all the plates are engaged with the gear
shaft splines. Rotate the output gear back and forth to
create maximum backlash then withdraw the gear
taking care not to disturb the pack.
9 Place the first two disc springs 8B with their convex
sides uppermost, onto the clutch pack. (There are four
disc springs, which are identical). Place the other two
disc springs 8A, with their convex sides down, onto the
first two - refer to inset A.
115 - 2
Section F Transmission
9803/3280
Section F
115 - 2
Issue 1
Synchro Shuttle Gearbox
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