A maximum of 0.002 inch (0.05 mm) of wear is allow-
able. Replace the thrust plates if they are scored,
Wear in excess of 0.007 inch cut-out necessitates re-
eroded, or pitted.
placement of the gear housing. Place a straight-edge
across the bore. If it is possible to slip a 0.007 inch
Check the center of the thrust plates where the gears
(0.018 mm) feeler gauge under the straight edge in the
cut-out area, replace the gear housing.
Pitted thrust plates indicate cavitation or oil aeration.
Pressure pushes the gears against the housing on the
Discolored thrust plates indicate overheating, probably
low pressure side. As the hubs and bushings wear, the
due to insufficient oil.
cut-out becomes more pronounced. Excessive cut-out
in a short period of time indicates excessive pressure or
prescribed limits, check for shock pressures or tamper-
If either the dowel or dowel hole is damaged, the dowel
ing. Withdraw an oil sample and check it, and the reser-
or machined casting, or both, must be replaced.
voir for dirt. Where the cut-out is moderate, (0.007 inch
or less) the gear housing is in good condition and may
If more than reasonable force is required to seat the
dowels, the cause may be poorly deburred or dirty parts,
cocking of the dowel in the hole, or improper pin-to-hole
Any scoring on the gear hubs necessitates replace-
ment. Scoring, grooving, or burring of outside diameter
of teeth requires replacement. Nicking, grooving, or fret-
If the gears are replaced, the bushings must be re-
ting of teeth surfaces also necessitates replacement.
placed. The bushings should fit into the bore with a
heavy press fit.
SEALS AND GASKETS.
Replace the drive shaft if there is any wear detectable by
touch in the seat area or at the drive coupling. The maxi-
Replace all rubber and polymer seals, including all 0-
rings, thrust plate channel seals, shaft seal, and gasket
mum allowable wear is 0.002 inch (0.05 mm).
Wear or damage to splines, keys, or keyways necessi-
Examine the plugs in the shaft end and port end cover to
ensure they are in the proper position and tight. The
P315 and P330 should have two plugs in both the shaft
The thrust plates seal the gear section at the sides of the
end and port end in tandem units only. The P350 and
gears. Wear here will allow internal slippage, which
P365 have one plug in their shaft and port ends high
means that oil will bypass within the pump.
pressure side only.