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
.
C AU TI ON :
There is ap p ro x im at ely 26700N (6000lb f )
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 t he c lut c h d rum ret aining c irc lip
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
9803/3280
Section F
115 - 2
Issue 1
Synchro Shuttle Gearbox