10 - 1
FAULT
A One or both brakes do not apply.
(Brake travel not excessive, brakes
not pulling to one side).
B Pedal travel excessive (but not
touching floor).
C Applying one brake (pedals
unlocked) also partially engages
the other brake.
D Pedal hard to operate.
E Pedals touch floor under constant
pressure - no fluid loss.
F Pedals touch floor under constant
pressure - and fluid loss.
G Pulling to one side when pedals
locked together.
Brake System
Note: The brakes generate a high temperature when operating, this means that the casing will be hot to touch, this condition
is normal. Note aslo that 4WS machines do not have dual pedal braking.
POSSIBLE CAUSE
1 Master cylinder fault.
2 Friction/counter plate distortion.
1 Air in hydraulic system.
2 Leak in hydraulic system.
3 Friction/counter plate distortion.
1 Valve stem seal inside (non-active)
master cylinder piston not sealing.
1 Tightness at pedal pivot.
2 Fluid contamination/seal damage.
3 Misaligned push rod/pedal.
4 Kinked or crushed brake pipes.
Items 5 to 7 are for machines fitted
with servo assisted brakes only:
5 Vacuum failure due to low vacuum
at source.
6 Blocked/leaking vacuum pipe.
7 Servo defect.
1 Master cylinder fault.
2 Friction/counter plate distortion.
3 Air in hydraulic system.
1 External fluid leaks.
2 Internal fluid leaks.
1 Compensating feature not
working.
ACTION
1 Check master cylinder in single and
coupled pedal modes to identify fault
area, service as required.
2 Check friction/counter plates.
1 Check fluid reservoir level. Check for
fluid/air leaks, rectify as required.
2 Check for fluid loss at master
cylinder and brake piston, all pipes
and fittings for loose connections.
Rectify as required.
3 Renew friction/counter plates -
BOTH sides.
1 Renew master cylinder piston.
1 Inspect pedal pivot. Free-
off/lubricate.
2 Flush system and renew all hydraulic
seals.
3 Check and rectify as required.
4 Check/renew brake pipework.
5 Inspect/service engine mounted
exhauster unit as required.
6 Check/renew vacuum pipe.
7 Renew servo unit.
1 Check master cylinder in single and
coupled pedal modes to identify fault
area, service as required.
2 Renew friction/counter plates -
BOTH sides.
3 See item B.1.
1 Visually check brake circuit for fluid
loss, service as required.
2 Refer to Service Procedures -
Brake Piston Seal Leakage Test.
1 Inspect master cylinder
compensating operation. Check if
blockage in bridging pipe. Service as
required.
Section G Brakes
9803/3280
Section G
10 - 1
Issue 1
Fault Finding
To Next Page
Need help?
General
