• Effect of Trouble

• Probable Cause

• Some of the Remedies for      Problem

High wear in pump

Unwanted water in fluid

Water vapor Faulty breather, strainer Heat exchanger leakage ' wrongful clean-up practice Water in makeup fluid

Pressure shocks

Cogging load Worn release valve

Mechanical considerations Needed repairs

Worn compensator Slow response in check valves

Make repairs Replace or relocate

Servo pressure too low to sustain firm control

Increase pressure and check pressure drop through servo filter

Too much decompression energy rates

Improve decompression control

Excessive line capacitance (line volume, line stretch, accumulator effects)

Lower line size or lengths. Get rid of hose Bleed air

Barrel blow-off

Double check pump hold-down, rotary motion group, drain pressure

Heating of fluid

Excessive pump leakage

Look over again the case drain flow and repair as required Fluid too thin Improper assembly, port timing

Relief valve

Set too low (compared to load or to compensator) Not stable enough that is caused by back pressure, worn parts

Compensator

Set too high (compared to release) Worn parts

Pump too large for fluid needs

Choose smaller pump displacement

Heat exchanger

Water turned off or too little flow Water too hot Fan clogged or restricted Efficiency lowered by mud or scale deposits On and off hydraulic fluid flow

Reservoir

Too little fluid Entrained air in fluid Improper baffles Keeping in air blanket that prevents heat rejection Heat pickup from adjacent equipment

• 11 and 14 in.³

• Original Dimension

• Max. Revised From Original Dimension

• Min. Dimension After Revised

Port plate face

.725/.715"

.010"

.705"

Cylinder barrel face

5.880"

.010"

5.870"

Shoe retainer face

.4387.437"

.005"

.432"

Piston shoe face (pocket)

.020"

.010"

.010"

Creep plate face

.251/.250"

.010"

.240"

Face plate

None

Replace

• Elffect of Trouble

• Probable Cause

  Some of the Remedies for Problems

Noisy Pump

Air in Fluid

Leak in suction line Leak at shaft seal Low fluid level Turbulent fluid Return lines above fluid level Gas leak from accumulator Too much pressure drop in the inlet line from a pressurized reservoir Suction line strainer trying to be an air trap as well

Cavitations in pump or motor rotating group

Fluid too cold and viscous Fluid too heavy Shaft speed too high Suction line too small Suction line collapsed Suction strainer too small Suction strainer not clean Working altitude too high Boost or replenishment pressure too low Replenishment flow too small for dynamic conditions

Misaligned shaft

Faulty installation Improper in mounting Axial interference Faulty coupling Extreme overhung loads

Mechanical fault in pump

Piston and shoe looseness or failure Bearing failure Incorrect port plate selection or index Eroded or worn parts in the displacement control

Erosion on barrel ports and port plate

Air in fluid

See above

Cavitations

See above

High wear in pump

Excessive loads

Lower pressure settings Reduce speeds

Contaminant particles in fluid

Faulty filter maintenance Filters too coarse Putting in dirty fluid to system Reservoir openings Reservoir breather Improper line replacement

Improper fluid

Fluid too thin or thick for working temperature range Breakdown of fluid with time/temperature/shearing effects wrong additives in new fluid Breakdown of additive effectiveness with chemical aging

Improper repair

Incorrect parts,procedures, dimensions, finishes