Variations in flow

A) Valve compensator spool binding


B) Insufficient pressure differential across the orifice

C) Fluid viscosity too high or too low (needle valve and pressure compensated valves)

A) Disassemble and clean, flush system. Check for burrs on spool and body.

B) Increase system pressure. Decrease system load.

C) Warm oil to normal operating temperature. Change fluid to recommended SSU. Change valve to temperature pressure compensated valve.

Improper flow rate

A) Needle valve adjustment incorrect
B) Additional line restriction



C) Restrictions in valve passages or orifice area.

A) Readjust needle valve.

B) Check for collapsed or kinked lines. Check for proper tube fitting and hose size.

C) Disassemble and clean; flush system.

Fluid is overheating

A) Excess flow over relief valve




B) System pressure too high

C) Contamination

A) Adjust pump GPM (variable volume pump). Reduce pump RPM's. Change to small GPM pump.

B) Lower system pressure.

C) Drain, clean and flush system.