Greenlee / A Textron Company 16 4455 Boeing Dr. • Rockford, IL 61109-2988 USA • 815-397-7070
980 Hydraulic Power Pump
Troubleshooting—Pilot-Operated Valve
Pilot-operated valve will not The pilot piston does not return freely.
See Hydraulic Schematic (7) and refer to
open. Pilot-operated valve
Low-Pressure Relief Setting, Figure A4
will not open fully. Pilot-operated
in the Repairs section of this manual.
valve opens too slowly.
Oil is cold. Preheat oil. Without an accessory
connected to the coupler, run the pump
to build pressure, then release. Repeat
until oil is warm.
Wrong oil viscosity. Replace oil with the type recommended
in the Specifications section of this
manual.
Oil is dirty. Replace oil with the type recommended
in the Specifications section of this
manual.
Oil is cold. Preheat oil. Without an accessory
connected to the coupler, run the pump
to build pressure, then release. Repeat
until oil is warm.
Pilot piston components may be worn Clean and inspect items 42-49.
or damaged. Replace parts as necessary.
Low-pressure bypass check valve is
See Hydraulic Schematic (4).
set incorrectly.
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 in
bypass check valve is damaged. the Repairs section of this manual.
PROBLEM PROBABLE CAUSE POSSIBLE REMEDY
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