GEAR HOUSINGS:
BEARINGS
Wear in excess of 005" cut-out necessitates replacement
If gears are replaced, bearings must be replaced Bearings
of the gear housing.
should fit Into bore with a light press fit. A neat hand fit is
allowable If bearings can fall out, bore may be oversize.
Place a straight-edge across bore If you can slip a 005"
feeler gauge 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 bearings wear, the cut-out
becomes more pronounced Excessive cut-out. In a short
SEALS AND GASKETS
period of time Indicates excessive pressure or oil
Replace all rubber and polymer seals whenever
contamination
If the relief valve settings are within
disassembling pump Include all "0" rings, pocket seals
prescribed limits, check for shock pressures or tampering
behind thrust plates, shaft seal, and gasket seals.
Withdraw oil sample and check it and tank for dirt.
Where cut-out is moderate, 005" or less, gear housing Is in
good condition, and both parts are of the same size,
housing may be flopped over and reused
CHECK VALVES
Examine small check valves In shaft end cover to make
sure they are Intact and functioning If there are no check
valves here, make sure the high pressure side of the shaft
end cover is plugged with an Allen plug.
THRUST PLATES
GEARS
The thrust plates seal the gear section at the sides of the
gears Wear here will allow Internal slippage, that is, oil will
Any wear on gear hubs detectable by touch, or in excess of
bypass within the pump.
002" necessitates replacement Scoring, grooving, or
burring of outside diameter of teeth requires replacement
002" maximum wear is allowable Replace thrust plates if
Nicking, grooving, or fretting of teeth surfaces also
they are scored, eroded, or pitted
necessitates replacement.
Check center of thrust plate where the gears mesh.
Erosion here indicates oil contamination.
Pitted thrust plates indicate cavitation or oil aeration.
Discolored thrust plates indicate overheating, probably
insufficient oil.
DRIVE SHAFTS
Replace if there is any wear detectable by touch in the seal
areas or at the drive coupling 002" wear is the maximum
allowable.
Wear in the shaft seal areas indicates oil contamination
Wear or damage to splines, keys, or keyways necessitates
replacement.
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