Greenlee / A Textron Company 17 4455 Boeing Dr. • Rockford, IL 61109-2988 USA • 815-397-7070
980 Hydraulic Power Pump
Troubleshooting—Pilot-Operated Valve (cont’d)
Pilot-operated valve will A particle of dirt or some other foreign Disassemble, clean and inspect
not close. object is holding the low-pressure spring (70) and 9/32" ball (71). Replace
bypass check valve open. parts as necessary.
Low-pressure bypass check valve
See Hydraulic Schematic (4).
is faulty.
If set too low: T
he pump cannot shift to
the high-pressure stage. See Pressure
Adjustment for the Low-Pressure Bypass
Check, Figure A5 in the Repairs section
of this manual.
If set too high: The pump cannot
restart under pressure. See Pressure
Adjustment for the Low-Pressure
Bypass Check, Figure A5 in the Repairs
section of this manual.
The ball seat of the low-pressure See Ball Seat Refinishing, Figure B2,
bypass check valve is damaged. B3 and B4 in the Repairs section of
this manual.
Low-pressure bypass check ball seat is Replace the pump block (84).
oversized.
PROBLEM PROBABLE CAUSE POSSIBLE REMEDY
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