TSUM - 2-031 Valve Stack Fault Finding Guide

TM 5-5420-279-23

TSUM - 2-031 Valve Stack Fault Finding Guide

Introduction

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.

Typical Failures

Compensator valve not opening.

Shuttle Valve leaking.

Back to back check valve leaking.

Load sense system not operating.

Compensator Failure

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.

Gauge

Nothing

Operate Valve to put Pressure

Operate Valve to put

Operated

to `A' Port

Pressure to `B' Port

653 psi

3480 psi

(4500 kPa)

(24000 kPa)

Unless limited

2900 psi

0 bar

by relief or

(20000 kPa)

reducing valve

Unless limited

2900 psi

0 bar

by relief or

(20000 kPa)

reducing valve

2900 psi

0 bar

(20000 kPa)

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.

2-91