Key
A Forward/reverse clutch unit
A1 Forward clutch
A2 Reverse clutch
A3 Forward/reverse front shaft
A4 Forward/reverse front shaft bearing
B Transmission oil pump
C Torque converter pressure regulating valve
D Oil pressure maintenance valve
E Solenoid control valve
F Idler gear bearing
K Output shaft bearing
L 4WD output yoke (if fitted)
M 2/4WD clutch unit (if fitted)
N 4WD solenoid control valve (if fitted)
P Oil strainer
Q Oil filter
S Torque Converter
V Torque converter relief valve
Z Oil Cooler
Transmission
9803/3280 Issue 1
Synchro Shuttle Gearbox
Hydraulic and Electrical Operation
Oil from the pump B is fed through an internal
passage via the filter to the pressure maintenance
valve D, which maintains pressure to the solenoid
valve E for clutch selection. Excess oil from the
maintainance valve flows back through the casing
to the torque converter S. Oil enters the converter
between the converter hub and the stator support,
and leaves between the stator and the input shaft.
Pressure in the converter is controlled by a
regulating valve C which dumps oil from the
converter line back to the sump.
Torque converter relief valve V acts as a safety
valve should the system pressure suddenly rise
obove normal, protecting the torque converter from
being damaged.
Oil from the torque converter S flows out of the
transmission to the external oil cooler Z, returning
at the rear of the transmission unit to pass through
the centre of the reverser shaft for clutch
lubrication.
Lubrication oil is also provided via a pump drain
line to the forward/reverse front shaft bearing A4.
The drain from pressure maintenance valve D also
provides lubrication for idler gear bearing F.
Solenoid Valve (E) Operation
Pressurised oil at the solenoid valve E is used to
control the forward/reverse clutches A1 and A2.
Forward:
In the diagram, electrical solenoid E1 is energised
by the forward/reverse control lever in the cab.
Pressurised oil is diverted to the forward clutch A1
and forward is selected. A restrictor orifice in the
feed to the solenoid valve modulates the pressure
to the clutch to smooth engagement. At the same
time oil from reverse clutch A2 is diverted back to
the sump via solenoid valve E.
Reverse:
When the reverse is selected electrical solenoid E2
is energised and pressurised oil is diverted to the
reverse clutch A2. At the same time oil from clutch
A1 is diverted back to the sump
Neutral:
When neutral is selected (via the control lever or the
transmission dump button), the flow of the
pressurised oil is blocked at the solenoid valve. No
solenoids are energised and no clutches engaged.
For a further detailed description refer to
Forward/Reverse Clutch - Operation.
The 2/4WD unit M is controlled by solenoid valve N.
For a full description of 2/4 wheel drive clutch
operationrefer to 2/4WD Clutch Operation.
16 - 4 16 - 4
Basic Operation
Section F Section F
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