Greenlee 975 Instruction Manual page 14

Troubleshooting—Pilot-Operated Valve
Problem
Pilot-operated valve will not open.
Pilot-operated valve will not open
fully. Pilot-operated valve opens too
slowly.
Greenlee Tools, Inc.
Probable Cause
The pilot piston does not return
freely.
Oil is cold.
Wrong oil viscosity.
Oil is dirty.
Pilot piston components may be
worn or damaged.
Low-pressure bypass check valve is
set incorrectly.
The ball seat of the low-pressure
bypass check-valve is damaged.
14
975 Hydraulic Power Pump
Probable Remedy
See Hydraulic Schematic (7) and
refer to Low-Pressure Relief Setting,
Figure A4 in the Repairs section of
this manual.
Preheat oil. Without an accessory
connected to the coupler, run the
pump to build pressure, then release.
Repeat until oil is warm.
Replace oil with the type recom-
mended in the Specifications section
of this manual.
Replace oil with the type recom-
mended in the Specifications section
of this manual.
Clean and inspect items 42-49.
Replace parts as necessary.
See Hydraulic Schematic (4).
If set too low: The 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.
See Ball Seat Refinishing, Figure B2
in the Repairs section of this manual.
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