TM 5-4310-343-35
a. Crankshaft assembly. Measure diameter of shaft; both end bearing diameters must be between 0.98111 and
0.9847 inch and the center diameter must be between 0.8750 and 0.8752 inch. Be sure oil hole and passage through
shaft are clear.
b. Cam assembly (keystone). Using air spindle Part Number 209984 or equivalent, minimum and maximum air
gages Part Number 209986 or equivalent and inspect diameter of cam assembly. Diameter of cam assembly must be
between 0.8759 and 0.8763 inch. Inspect piston pin bore diameter. Diameter of piston pin bore must be between 0.5008
and 0.5012 inch. Inspect plunger bearing surfaces for grooves or ridges and check that all four oil holes are clear.
c. Cylinder head. Inspect for nicks or scratches on gasket seating surfaces.
d. Valves and seats. Inspect valves and seats for nicks, scratches or burrs.
e. Cylinder and plunger assemblies. Inspect for nicks, scratches burrs and carbon deposits. Examine for excessive
wear by checking clearance. Maximum permissible clearances are 0.003 inch for the first stage, 0.0016 inch for the
second stage, and 0.0003 inch for the third and fourth stages. Because the cylinder and plunger or piston assemblies are
matched parts, dimensions alone cannot be used to judge continued usefulness.
Blowby and pump time are the
important performance characteristics and can be determined only by running in the complete compressor.
5-11. Repair and Replacement.
a. Repair. Repair of the components is limited to polishing bearing surfaces and refinishing graphite coated parts.
When worn graphite coated parts are to be recoated, clean thoroughly by immersing them in Tecsolv 204 (Tect Inc.,
Dumont, N.J. ), Pentalene (Sharples Chemicals, Inc., Philadelphia, Pa. ) or equivalent. Dry with clean compressed air.
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