PGP/PGM 300 Series
Service Manual HY09-SM300/US
10
Parker Hannifin Corporation
Gear Pump Division
Youngstown, OH
Guideline for acceptable wear
Gear Housings
Wear in excess of .007" cut-out necessitates
replacement of the gear housing. Place a straight-edge
across bore. If you can slip a .007 feeler gage under
the straight-edge in the cut-out area, replace
the gear housing.
Pressure pushes the gears against the
housing on the low pressure side. As the
hubs and bushings wear, the cut-out
becomes more pronounced. Excessive
cut-out in a short period of time indicates excessive
pressure or oil contamination. If the relief valve settings
are within prescribed limits, check for shock pressures
or tampering.
When the cut-out is moderate, 007" or less, the gear
housing is in good condition and may be reused.
Gears
Any scoring on gear hubs necessitates
replacement. Scoring, grooving, or
burring of the outside diameter of the
teeth requires replacement. Nicking,
grooving, or fretting of teeth surfaces also
necessitates replacement.
Drive Shafts
Replace if there is any wear
detectable by touch in the seal
area or at the drive coupling. The
maximum allowable wear is .002".
Wear in the shaft seal area indicates oil
contamination. Wear or damage to splines, keys,
or keyways necessitates replacement.
Thrust Plates
The thrust plates seal the gear section at
the sides of the gears. Wear here will allow
internal slippage, that is, oil will bypass
within the pump.
A maximum of .002" wear is allowable. Replace
thrust plates if they are scored, eroded or pitted.
Check center of thrust plates where the gears mesh.
Erosion here indicates oil contamination.
Pitted thrust plates indicate cavitation or oil aeration.
Discolored thrust plates indicate overheating, likely due
to insufficient oil.
Dowel Pins
If either the dowel or dowel hole is damaged,
the dowel or machined casting, or both, must
be replaced.
If more than reasonable force is required to
seat dowels, the cause may be poorly deburred
or dirty parts; cocking of the dowel in the hole or
improper pin-to-hole fit.
Bushings
If gears are replaced, bushings must be
replaced. Bushings should fit into the bore with
a heavy press fit.
Seals and Gaskets
Replace all rubber and polymer seals,
including all "0" rings, thrust plate channel
seals, shaft seal and gasket seals.
Plugs
Examine the plugs in the shaft end and port
end cover to make sure that they are in the
proper position and tight. The PGP/PGM315 and
PGP/PGM330 should have two plugs in both the
shaft end and port end in tandem units only. The
PGP/PGM350 and PGP/PGM365 have one plug in
their shaft and port ends high pressure side only.
