POWER SENSOR VALVE ADJUSTMENTS
3. Faulty power sensor valve
1. Install a 3000 PSI gauge in the main hydraulic
valve pressure check port. Install another 3000
NOTE: Refer to troubleshooting hydraulic sys-
PSI gauge in the power sensor valve check port.
tems on page 174.
(Refer to the picture on page 203 for the loca-
Problem No. 2
tion of this check port.) Warm the hydraulic fluid
to operating temperature.
Bucket lifts slowly with or without a load
2. With the engine at low idle. raise the boom until
Possible causes
it contacts the stops. As the boom contacts the
stops, read both gauges.
1. Power sensor pressure adjusted incorrectly
3. The reading on the gauge attached to the power
2. Faulty pilot section of power sensor valve
sensor will drop to zero, when the gauge attached
to the main hydraulic valve reads approximately
3. Stuck spool
1600 PSI on the 125 and 275 tractor shovels, and
1700 PSI on the 175 tractor shovel.
4. Broken spool return spring
4. If the gauge attached to the sensor valve does
5. Small hole thru rear land of spool plugged
not drop to zero. If the gauge attached to the
s e n s o r valve does not drop to zero when the
Problem No. 3
other gauge IS at the correct pressure, the
sensor valve must be adjusted.
Low engine RPM's when raising a loaded bucket
5. Adjust the sensor valve by removing the acorn
Possible causes
nut and locknut and turning the adjusting screw
c l o c k w i s e to increase pressure and counter-
1. Faulty engine
clockwise to decrease the pressure. After
tightening the locknut and replacing the acorn
2. Power sensor pressure incorrectly adjusted
nut check the pressure to make sure that it has
not changed.
3. Faulty pilot section of power sensor value
I f the power sensor valve cannot be adjusted
properly it will be necessary to troubleshoot the
4. Stuck spool
system as outlined in the following steps.
5. Small hole in rear land of spool plugged
Troubleshooting the Power Sensor Valve
Problem No. 4
When troubleshooting the power sensor valve, re-
member that it is only one of several components
Oil leaking between valve and adaptor plate
used in the hydraulic system. Because all the com-
ponents must operate correctly to have the system
Possible causes
operate correctly, it is a good idea to examine the
pump, the cylinders and the main hydraulic control
1. Faulty O-rings
valve to see that they are in good operating con-
dition.
2. Loose cap screws
Problem No. 5
Problem No. 1
Oil leaks between adaptor plate and pump
Bucket lifts slowly when loaded.
Possible causes
Possible causes
1. Faulty O-rings
1. Power sensor pressure set too low
2. Loose cap screws
2. Faulty pilot section of power sensor valve
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