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Bulletin 948675A
7
Bulletin 948675A
CONTROL SERVICE MANUAL
TROUBLESHOOTING
PROBLEM
CAUSES
REMEDY
Unresponsive or
Unstable Control
Swashblock bearing surface and/or saddle bearings worn or
damaged
Refer to 948034 Pump Service Instructions.
Fluid is contaminated
Inspect and clean if necessary. Refer to Filtration
Recommendations Bulletin 90007.
Contamination trapped between control piston and bore not
allowing piston to move smoothly
Inspect and clean if necessary. Replace damaged
parts.
Contamination trapped between control spool and bore not
allowing spool to move smoothly
Insufficient control flow
Increase size of control orifice “OP 6.”
Worn or damaged pilot relief seat and/or poppet
Inspect and replace if necessary.
Faulty remote function circuit
Hydraulic line between remote fuction and pump port RP1 is
incorrect
Change hydraulic line.
Insufficient Outlet
Volume
Swashblock bearing surface and/or saddle bearings worn or
damaged
Refer to 948034 Pump Service Instructions.
Low input drive speed
Worn cylinder barrel and/or valve plate mating surfaces
Failed drive shaft
Worn or damaged piston shoes and/or swashblock
Worn pistons and/or piston bores
Maximum volume stop adjusted incorrectly
Adjust maximum volume stop CCW to increase flow.
Pressure compensator is set too close to operating pressure
Adjust pressure compensator CW to increase
pressure.
Control piston stuck off stroke
Inspect and replace if necessary.
Faulty remote function circuit
Unable to Develop Full
Pressure
System requires more flow than available
Check system for leaks or open functions.
Pressure compensator adjustment not set correctly
Adjust pressure compensator CW to increase
pressure.
Contamination in control spool
Inspect and clean if necessary.
Worn or damaged pilot relief seat and/or poppet
Control piston stuck off stroke
Faulty remote function circuit
Excessive Pressure
Swashblock bearing surface and/or saddle bearings worn or
damaged
Refer to 948034 Pump Service Instructions.
Pressure compensator adjustment not set correctly
Adjust pressure compensator CCW to decrease
pressure.
Contamination in “OP 3” or “OP 4”
Inspect and clean if necessary.
Restricted passage between outlet and control spool
Contamination trapped between control piston and bore is not
allowing piston to move smoothly
Inspect and clean if necessary. Replace damaged
parts.
Contamination trapped between control spool and bore not
allowing spool to move smoothly
Faulty remote function circuit
Inspect and replace if necessary.
