jcb 1CX, Service Manual

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Section E Hydraulics
9803/8550
Section E
Issue 1
Pumps 12 - 13
Fault Finding
from machine no. 751012
Machine veers to one side when travelling.
If the machine does not travel in a straight line, proceed as
follows:
Fault
1 Machine veers excessively to left in forward travel
2 Machine veers excessively to right in forward travel
3 Machine veers excessively to left in reverse travel
4 Machine veers excessively to right in reverse travel
Travel Speed
The maximum speed of the machine should be checked
following the above adjustments. This involves raising the
machine off the ground and checking the wheel speeds
using a stroboscopic meter.
! !
WARNING
The following procedure requires the machine to be
disabled (wheels raised off the ground, work function
disconnected etc.) while the work is carried out.
HYD 8-1/1
Place the machine safely onto blocks, so that all four wheels
are clear of the ground. Ensure that the machine is stable.
Stick a piece of reflective tape on a wheel rim. Start the
engine and run at maximum speed then operate the drive
control. Measure the speed of wheel rotation in each
direction which should be 81 rev/min. An allowance of 2%
above this figure is permissible. Check the speed of the
wheels on the opposite side of the machine.
Note that excessive wheel speed may result in cooling
problems due to overheating of the hydraulic oil.
If necessary the appropriate adjusting screws should be
screwed in
1
/
4
turn at a time until the correct wheel speed is
achieved. Stop the engine while adjustment is carried out.
If the left hand wheels are rotating too fast in forward or
reverse, screw in adjusters B (forward) or D (reverse) to
achieve the correct speed. If the right hand wheels are
rotating too fast, screw in adjusters A (forward) or C
(reverse).
Note: On standard machines the displacement limiter
adjustment screws are set to allow a gap when the servo
piston is at full travel. Therefore to limit piston travel it is
necessary to screw in the adjuster screws to eliminate the
gap before adjustment can take place. On High-flow
machines there is no gap between the adjuster screws and
the servo piston.
Loosen locknut on adjuster screw A, screw in adjuster screw
1
/
4
turn and tighten locknut. Try machine. Keep adjusting
1
/
4
turn at a time until straight line travel is achieved.
Proceed as for fault 1 but adjust screw B.
Proceed as for fault 2 but adjust screw C.
Proceed as for fault 3 but adjust screw D.
Further small adjustments may be required as covered in the
fault table above.
12 - 13
D
B
C
A
S245710
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