Transmission
9803/3280 Issue 1
Syncro Shuttle Gearbox
Forward/Reverse Clutch Operation
The forward/reverse clutch unit 1 transfers drive from the
input shaft A3 to either gear G1 or gear G2 depending on
which of the two clutches (A1 or A2) is engaged, giving
forward or reverse drive. When neither clutch is engaged,
neutral is selected.
The clutches are of the wet, multi-plate type.
The clutch housings and input shaft are a one piece
assembly A3. The assembly is permanently driven by the
engine via the torque converter. Clutch counter plates 3 are
also permanenty driven via meshing teeth inside the clutch
housings.
Clutch friction plates 4 are meshed with the gear/plate
carriers (G1 and G2).
In the diagram, clutch A1 is engaged. The counter plates 3
and friction plates 4 are pressed together by hydraulically
actuated piston 5. Drive is then transmitted from the input
shaft to the gear G1.
Clutch A2 is disengaged and no drive is transmitted to
gear/plate carrier G2. The gear is also free to rotate on the
input shaft assembly.
Actuation of the hydraulic pistons 10 and 5 is controlled via
three position solenoid valve E
†
.
When neutral is selected, solenoids E1 and E2 are
deactivated and the flow of pressurised oil to the clutches is
blocked. Springs 8 and 9 move the pistons away from the
clutch plates and oil from both pistons is vented to the
sump.
When either forward or reverse is selected, the solenoid
valve E diverts pressurised oil via cross drillings inside the
input shaft A3 to the appropriate clutch (piston 10 or 5) in
the unit. Pressure from the other clutch is vented to the
sump via the solenoid valve spool. Oil is prevented from
leaking by seals 6 on the pistons and ring seals 7 on the
input shaft A3.
† The valve E is shown using symbols. For an explanation of
how the symbols work, see Section E, Introduction to
Hydraulic Schematic Symbols.
26 - 1 26 - 1
Systems Description
Section F Section F
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