Greenlee 975 Instruction Manual page 12

Troubleshooting—Hydraulic Pump (cont'd)
Problem
Ram advances erratically and
retracts erratically.
Pump will not build enough
pressure to complete the job.
Ram advances slowly.
Greenlee Tools, Inc.
Probable Cause
Air in the hydraulic fluid.
High-pressure system is faulty.
System has an external hydraulic
leak.
Pilot-operated valve will not close.
Low-pressure system is at fault.
At high-pressure inlet, the check ball
has too much travel.
The high-pressure piston is stuck.
Internal hydraulic fluid leak.
High-pressure relief valve failure.
12
975 Hydraulic Power Pump
Probable Remedy
Refer to Purging (Bleeding) Air in the
Maintenance and Service section of
this manual.
See Hydraulic Schematic (5) and
refer to Figure A5-1 in the Repairs
section of this manual.
Visually inspect hoses, connectors
and fittings for leaking hydraulic
fluid. Replace faulty components.
See "Troubleshooting—Pilot-
Operated Valve" at the end of this
Troubleshooting section.
Find "Low-pressure system partial
or complete failure" under Probable
Causes in this Troubleshooting
section.
See Check Ball Travel at High
Pressure Inlet, Figure A5-1. If the
seats are leaking, see Ball Seat
Refinishing, Figure B2 in the Repairs
section of this manual.
Disassemble, clean, and inspect the
high-pressure bushing (75) and high-
pressure piston (76). Replace parts
as necessary.
Inspect and replace as necessary:
O-ring Plug (68)
Cavity Insert (74)
High-Pressure Bushing (75)
High-Pressure Relief Valve (72)
Readjust, re-seat or replace valve
(72).
4455 Boeing Dr. • Rockford, IL 61109-2988 USA • 815-397-7070