15 - 1
Hydraulic System
- Fixed Flow
Fault Finding Contents
Page No.
Introduction
15 - 1
Lack of power in all hydraulic functions
15 - 1
All hydraulic rams slow to operate
15 - 2
One hydraulic service fails to operate or is
slow to operate
15 - 2
The engine tends to stall when the
hydraulics are under load
15 - 2
A spool is sticking
15 - 3
Leaking Oil Seal (Control Valves)
15 - 3
Ram creep
15 - 3
Hydraulic oil becomes too hot
15 - 4
Section E
9803/3280
Section E
15 - 1
Issue 1
Fault Finding
Fault
Probable Cause
Action
1
Lack of power in all hydraulic functions.
Insufficient hydraulic fluid.
Check for leaks and top up as required.
Hydraulic leaks in system.
Check hoses, replace as required.
Engine performance.
Check engine performance, see
transmission section for stall speed
test procedures.
Main relief valve (MRV)
Check and adjust as required.
setting incorrect.
Low pump flow.
Check pump flow, if required service or
replace pump.
Hydraulic tank breather
Clean or replace the breather
Tank filter by-pass valve
Check condition of hydraulic filter
Unloader valve pressure
Check pressure setting of the
setting too high
unloader valve.
..... continued
Introduction
The purpose of this section is to help you trace hydraulic
faults to a faulty unit (valve, actuator, ram etc). Once you
have t rac ed t he f ault y unit , ref er t o t he ap p ro p riat e
dismantling, inspecting and test instructions given elsewhere
in the hydraulics section.
To help identify circuits, valves, rams etc mentioned in the
fault finding procedures, refer to the hydraulic schematic
diagrams (near the beginning of the Hydraulics Section).
1
B ef o re yo u b eg in f ault f ind ing , read t he Saf et y
information at the beginning of this manual.
2
Make simple checks before say, stripping a major
component.
3
Make sure that the hydraulic fluid is at correct working
temperature (50 °C, 122 °F).
4
What ever the fault, check the condition of the hydraulic
fluid. Drain and replace if necessary.
5
Make any relevant electrical checks before moving on
to the hydraulics.
6
Be sure to remove ALL contamination and if possible
identify its origin. It may be part of a component from
elsewhere in the circuit.
7
Rep lac e any seals suc h as ' O' ring s b ef o re re-
assembling hydraulic components.