NMC-WOLLARD 2021Truax Blvd., Eau Claire, WI 54703, Phone (715) 835-3151, Fax (715) 835-6625
M140 Tow Tractor Manual No. 46054
PAGE 2-2
CHAPTER 2 MAINTENANCE
2 TROUBLESHOOTING
AUGUST 31, 2008
2.2 SYSTEM PRESSURE TEST
A reduction in steering responsiveness may be caused by a faulty pump, relief
valve, or internal leakage in the steering gear or power booster.
The relief valve is the least expensive and easiest power system component to
replace or repair. The relief valve is located in the lower port on the steering pump.
The relief valve may only require cleaning to work properly.
1.
leaks.
2.
ground.
3. Disconnect pump-to-booster pressure hose at the power booster. Use rags to
4.
5.
6.
7. Without steering, pressure should read below 150 psi. If above 150 psi, check
for hose restrictions. When corrected, proceed with this procedure.
8. Turn the steering wheel all the way to one of the stops, then the other. If
pressure rises to 1100-1200 PSI each time, the steering pump is OK. If
pressure exceeds 1200 PSI, replace the relief valve and re-test. If pressure is
below 1100 PSI, continue with step 9.
9.
PSI or greater, the pump is OK. The cause of the low pressure measured in
step 8 may be a faulty steering gear or power booster. If the pressure exceeds
1200 PSI, replace the relief valve and re-test. If pressure during this step is
below 1100 PSI, either the relief valve or pump is faulty.
0-2,000 psi
Guage
Shutoff
Valve
to
Pump
to
Booster
Spare
Hose
Pump-to-Booster
Hose
FIGURE 1. TEST GAUGE
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