T
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s
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9803/
3280
Issue
1
Powershift Gearbox
Clutch Operation - Forward, Reverse
The forward and reverse clutch units are very similar in
d esig n and o p erat e in t he sam e w ay. The f o llo w ing
description refers to one unit and can be applied to either
the forward or reverse clutch units.
The clutch
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, transferring drive to the mainshaft.
When neither clutch is engaged, neutral is selected.
The clutches are of the wet, multi-plate type.
The c lut c h housings and inp ut shaft are a one p iec e
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
two position solenoid valves
E1
and
E2
†.
When neut ral is selec t ed , so leno id s
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 for example clutch
A1
is selected to be engaged,
solenoid valve
E1
is energised and solenoid valve
E2
is de-
energised. Pressurised oil is diverted via cross drillings
inside the input shaft
A3
to the clutch piston
5
. Pressure
from clutch
A2
is vented to the sump via the solenoid valve
spool
E2
. 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
.
Clutch Operation - Mainshaft, Layshaft, 6 Speed
The mainshaft, layshaft and 6 speed units all incorporate
one clutch and not two, as in the forward and reverse units.
The operation of the single clutches is the same as for one
clutch in the forward or reverse units.
Clutch Operation - 2/4 Wheel Drive Clutch
The 2/4 wheel drive clutch is similar to the Synchro Shuttle
2/4 wheel drive clutch. See
Synchro Shuttle Gearbox, 2/4
Wheel Drive Clutch Operation
.
30 -
1
30 -
1
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