647
Model Code Page
41. Clutch
6000--8750 410 11
1. 4. 1997
HiShift, description
Repair instructions, see pages 411/12---14.
HiShift (option) controls the clutch pedal electro---hydrauli-
cally and it is unnecessary to depress the clutch pedal with
the foot. HiShift includes a hydraulic block attached to the
cab front wall with aid of the bracket, a new clutch pedal, a
new clutch fluid reservoir and electric parts.
Picture 9. HiShift assembly
A
B
C
D
E
F
Function of the hydraulic part
The working cylinder piston (A) pushes the clutch pedal
down (working pressure from the low pressure circuit). The
working pressure is controlled with the solenoid valve (B,
Y14), which in turn is controlled with aid of t he push buttons
(F) in the gear lever knobs.
When the s olenoid valve (B ) is energised (one of the but-
tons is depressed), the hydraulic pressure pushes the
pedal down. When the button is release d (solenoid unener-
gised), the permanent hydraulic pressure on the piston rod
side forces the piston to move inwards and the clutch pedal
returns to the upper position.
Function of the damping part
The damping cylinder has been connected to the clutch
fluid reservoir (E) by a hose.
When the working cylinder piston (A) releases the clutch, it
pulls the damping cylinder piston (C) mechanically out by
the pin and the damping cylinder is filled with clutch fluid
via the filling valve.
When the working cylinder solenoid valve is unenergised
(push button is released), the working cylinder piston
(pedal) rises first quickly the extent of the oblong hole in the
damping piston and then slo wer, because the return flow of
the clutch fluid into the reservoir is restricted.
The damping cylinder restriction can be changed by the
solenoid valve (D, Y15) so that when the driving speed is
less than 4 km/h, the solenoid is energised and the clutch
pedal rises up slo wer. With speeds over 4 km/h the sole-
noid is unenergised and the pedal rises faster. When the
shuttle lever button is used, the pedal always rises slower
regardless of the tractor driving speed.
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