Leakage In The System

Check the whole system for escaping fluid.  Serious leaks in the open are easy to find, however leaks often occur in concealed piping.  Install pressure gauges in discharge line near pump and then progressively block circuit downstream until leak is located.  A high leakage path through a valve or a component generates heat.  A hot spot in the circuit often indicates the point of leakage.

Aerated Hydraulic Fluid

Low fluid level prevents entrained air from having sufficient time to settle out of the oil.  Check oil level in reservoir daily.

Cavitation

Cavitation is the formation of a vacuum inside the pump.  This is usually caused by a restriction on the inlet, too high a viscosity (cold fluid), or insufficient head pressure (atmospheric pressure is require to push the oil into the pump, at high elevations, there is less pressure available to do the work).  Pseudo cavitation is similar to cavitation, but is caused by air entering the pump inlet, which will have similar effects as cavitation.  Look for loose/leaking components on all suction lines.  Un-corrected cavitation conditions will cause severe damage to pump components.

Lose/Worn Pump Parts

Look for worn gaskets and packing.  Replace if necessary.  Usually there is no way to compensate for ear in a component; it is always best to replace it.

Stuck Valves

Parts may be stuck by metallic chips, bits of lint, carbonized fluid etc.  If so, disassemble and clean thoroughly.  Avoid the use of files, emery cloth, steel hammers, etc. on machine surfaces.  Products of fluid deterioration such as gums, sludges, varnish, may also cause sticking.  Use solvent to clean parts and wipe dry before reassembly.  If parts are stuck by corrosion or rust, they will probably have to be replaced.

Overheating

1. Water shut off or heat exchanger clogged
2. Continuous operation at relief setting
3. Stalling under load, etc.
4. Fluid viscosity too high
5. Excessive slippage or internal leakage
6. Check stall leakage past pump, motors and cylinders
7. Fluid viscosity
8. Reservoir sized too small
9. Reservoir assembled without baffling or sufficient baffling
10. Case drain line from pressure compensated pump returning oil too close to suction line
11. Pipe, tube or hose I.D. too small causing high fluid velocities
12. Valving too small, causing high fluid velocity
13. Improper air circulation around reservoir
14. System relief valve set too high
15. Power unit operating in direct sunlight, or ambient temperature is too high
16. Pressure compensated pumps require the system relief be set 150 -200 PSI higher than compensator setting

#1264 Copyright 2008 Western Integrated Technologies. All rights reserved. This knowledge base document may not be published or redistributed without the written consent of Western Integrated Technologies