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TM 10-4310-391 -13&P
A burgling Boise Is characteristic when high pressure air Is drawn through the pump It should disappear quickly as the pressure within
the pump Is reduced If burgling continues, add sufficient additional ail through the exhaust port until burgling ceases.
III-3. SHAFT SEAL REPLACEMENT.
To replace the shaft seal of a pump, drain the ail and remove the pump pulley and key Remove the screws securing the old seal
and pry it loose with a screwdriver or similar wedge, being careful not to mar the surface of the pump body against which the seal bits
Discard the seal and bits gasket, Aspect all surfaces and repair any damages with a fine abrasive stone Wipe all sealing areas clean
and place a film of DuoSeal ail on both the shaft and the Inside bore of the new shaft seal Using a new gasket, carefully slide the new
seal into position and center it on the shaft It Is not necessary to apply any sealant to the gasket Tighten the mounting screws
uniformly and refill the pump with DuoSeal ail Follow Instructions Included m repair kit.
III-4. REPAIRING OIL LEAKS.
III-4a. Location, Cause and Effect.
Oil leaks may develop wherever two mating faces are sealed with a gasket Such seams may fall as the result of deterioration of the
gasket material, loosening of the screws caused by temperature vacations, or Improper care as the result of previous reassembly
Typical gasketed seams In a mechanical pump are located at the ail level window, the shaft seal, the ail drain, and the mating faces
of such mechanical surfaces as the Intake chamber cover, the ail case, and the exhaust chamber cover The Importance of a
gasketed seam is deter mined principally by bits function If it Is a vacuum seal, the ultimate performance of the pump Is dependent
upon it If it Is an ail seal, the pump may be operated satisfactorily for some time without loss of function Eventually, of course, a great
loss of ail may cause harmful damage.
III-4b. Repairing Technique.
An ail seam may be sealed by any of several methods When an O-ring Is employed, the surfaces of the O-ring and bits groove
should be wiped clean If the O-ring Is not badly deformed or scratched it may be reused by sealing with a slight film of vacuum ail or
vacuum grease Thin composition gaskets are generally used for large Irregularly shaped areas A replacement Joint of this type
should be thoroughly cleaned of all previous gasket material and the mating surfaces cleaned of any nicks.
III-5. REPAIRING VACUUM LEAKS.
III-5a. Surface Preparation.
Good vacuum seals are an essential and Important attribute of a good mechanical pump A good seal Is dependent upon the quality
of the mating surfaces as well as the sealant and bits preparation The mating faces should be carefully Inspected for any projections
or foreign particles which might Interfere with proper mating Slight projections such as nicks and burrs are most easily removed by
rubbing with a fine abrasive stone The surfaces of the mating parts may be washed with a solvent such as triethane or ace
tone after
which they must be thoroughly dried If a gasket Is required, a very thin coat of varnish should be applied to both faces before
assembly .
III-5b. Temporary Repair.
Temporary vacuum repairs are often made by covering the known leak with an industrial sealant such as Glyptal or Leak Lock Such
a practice, however, is not recommended for seals of a permanent nature.
III-6. MAINTENANCE OF HELIUM TRANSFER PUMPS.
A helium transfer pump Is especially constructed to provide a vacuum-tight storage space for helium gas within the ail reservoir as
well as the Internal passages of the pump itself Consequently, the importance of vacuum seals throughout the pump is in
creased,
especially between the mating face of the ail case and the pump body Instructions for the preparation of a gasketed vacuum seal are
given In Paragraph III-5a Equal care must also be applied to other areas such as the connection of the exhaust fitting and the ail level
window, each of which must be vacuum tight.
III- 7. DRIVE PROBLEMS.
If for any reason the pump will not operate, turn off the power and check the fuse and electrical connections Then try the power to the
motor only be removing the belt If the motor operates properly try hand
rotating the pump In the proper direction with the pump
intake port open If both turn freely then replace the belt and check the belt tension The ten
son should be Just sufficient to Dave the
pump without visible slippage Any greater tension will cause Boise and possible damage to the bearings of both the motor and pump
Make certain that both pulley grooves are clean and free from ail The pulleys must be fastened securely on their respective shafts,
and In parallel alignment
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