Operating Instructions, Form No. 102355, Back sheet 4 of 4
PROBLEM
CAUSE
SOLUTION
Pump does not build full
pressure (cont'd)
Cylinder(s) will not retract
Pump delivers excess oil
pressure
Automatic valve will not allow
pump to build full pressure
Automatic valve will not release
pressure
9. Internal leakage.
10. Sheared drive shaft key.
11. High pressure pump inlet or
outlet ball checks are leaking.
1. Check system pressure. If
pressure is zero, control valve is
releasing pressure and problem
could be in cylinder, linkage to
cylinder, or couplings.
2. Defective valve.
1. Relief valve set wrong.
1. Pilot pressure is too low.
2. Defective or oversize seat in
automatic valve.
3. Short rollers in low pressure
pump. A short roller will make
the pilot pressure erratic,
causing the valve to open
partially and bypass oil into the
reservoir past the ball seat.
1. Piston is sticking.
2. High pressure oil leaking past
the low-to-high pressure check
back to the piston in the
automatic valve, keeping the
piston closed.
9. Look for leaks around entire
inner mechanism. If there are no
visible leaks, the low-to-high
pressure ball check may be
leaking. Remove all parts. Look
for damage to the seat area in
the end plate body. Clean and
reseat, if needed. Inspect the
ball for damage; replace if
necessary.
10. Replace key and determine
cause of key failure.
11. Seat or replace valve head.
1. Look for broken return springs in
cylinders. See if couplers are
completely coupled. Sometimes
couplers have to be replaced,
because one check does not
stay open due to wear.
2. Inspect and/or replace parts.
1. Adjust relief valve.
1. Increase pilot pressure.
2. Replace ball and seat.
3. Replace short roller(s).
1. Remove, clean and polish
piston.
2. Seat ball check and carefully
add greater spring force to ball.
(Too much force causes priming
problems.)
