TSUM - 2-031 Valve Stack Fault Finding Guide
This procedure enables the maintainer to determine which component or components of a valve
stack are faulty and require replacement. It must be used in conjunction with the DSB Hydraulic
Circuit drawings G401/8001 Sheets 1 to 7 in Appendix E.
Compensator valve not opening.
Shuttle Valve leaking.
Back to back check valve leaking.
Load sense system not operating.
Check the appropriate sheet of drawing G406/8001- DSB Hydraulic Circuit.
Connect pressure gauges to pressure line P and load sensing line LS.
Connect pressure gauges in service lines A and B.
Operate Valve to put Pressure
Operate Valve to put
to `A' Port
Pressure to `B' Port
by relief or
by relief or
The above table shows the pressures that can be expected at the four pressure gauges when the
valves in the valve stack are operating normally. See the tables below for reference to specific
fault finding flow charts.
a. If no pressure is seen at A and B when the valve is operated to put pressure to those ports,
replace the Compensator and Shuttle valve.
b. If Zero pressure is seen at LS replace the back to back check valve.
c. If 200 psi (1400 kPa) is seen at A and B then the Solenoid or Manual Valve is OK and the
Compensator is OK, the problem is with the LS (load sense) shuttle valve.
d. If 650 psi (4500 kPa) is seen at the LS (load sense) port on the manifold, check the LS (load
sense) pressure at the interface manifold. If still only 650 psi at the Interface Manifold, then the
pump is at fault.