The Specialist In Drum Handling Equipment
MODEL 96MK1939-P
Star Hydraulic Pump
Operator’s Manual for Star Single Piston Hydraulic Pump as installed on:
400 Series Serial # 0604 to ____ (MMYY) 82 Series Serial # 0604 to ____ (MMYY)
405 Series Serial # 0604 to ____ (MMYY)
morsedrum.com
Copyright 2021 - Morse Mfg. Co., Inc. Form PL96MK1939 (0604-____) (Updated 16 Nov, 2021) 3
TROUBLE
Pump will not hold pressure
Pump fails to supply pressure
Pump piston does not draw a full
charge. (This is evident by a cushion
eect at the top of the pump stroke.)
Pump piston raises by itself under
pressure
Pump functions properly but will
generate only a given pressure below
its normal maximum pressure
POSSIBLE CAUSES
1. Release valve ball not seating properly
2. Ball valves not seating properly
3. Overload valve ball not seating properly
1. Lack of oil
2. Air bound pump
3. Release valve ball not seating properly
4. Small ball in ball valve circuit not seating
properly
5. Overload valve ball not seating properly
1. Air bound system
2. Lack of oil
Large ball in ball valve circuit not seating
properly
Overload valve not set properly
CORRECTIVE REPAIR
INSTRUCTIONS
Refer to RELEASE VALVE
Refer to PUMP VALVE
Refer to OVERLOAD VALVE
Refer to OIL
Refer to AIR BLEEDING
Refer to RELEASE VALVE
Refer to PUMP VALVE
Refer to OVERLOAD VALVE
Refer to AIR BLEEDING
Refer to OIL
Refer to PUMP VALVE
Refer to OVERLOAD VALVE
PUMP VALVE
If the pump fails to supply pressure or if the piston is under pressure at all times, the pump
valve may need a cleaning. Stand pump in upright position while removing valve plug and
valve seal. Tilt pump to remove valve springs and balls. Allow oil to drain from the reservoir
through these valve holes to wash foreign matter from hole. Lay pump on its side to clean
and inspect valve chamber. Be careful not to mar or nick ball valve seats. Clean valve
balls and spring in solvent. Replace rusted or corroded balls. Do not stretch ball springs.
To reassemble, insert, in sequence, small ball, small spring, large ball and large spring in
cleaned chamber. Finally, screw in valve seal plug (96CP13-151RP).
If the valve fails to operate properly after cleaning it may be necessary to re-seat the valve
balls. Remove the springs and tap each ball lightly in its respective seat using the 1/4” ball
seating tool (96CP13-42) for the small ball and the 3/8” ball seating tool (96CP13-43) for
the large ball. Remove balls to make sure they are not stuck to the seats. Reassemble
pump valve as before. See “Air Bleeding” instructions before attempting to operate the
pump.
RELEASE VALVE - SCREW TYPE
If the pump fails to lift or hold a load, the release valve may be dirty. Remove release
screw, release valve seal and 9/32” release valve ball. Clean and inspect valve seat and
screw. A slight depression in the end of the screw is not harmful. Screws with excessive
deformation should be replaced. Re-seat the release ball using the 1/4” ball seating tool
(96CP13-42). Insert the release valve packing using the valve packing inserting tool
(96P1A-40). Reinstall release screw. See “Air Bleeding” instructions before attempting to
operate the pump.
