CARRIER AIR BRAKE SYSTEM REPAIR INSTRUCTIONS
Section I. CARRIER AIR COMPRESSOR ASSEMBLY
head in water and apply 15 psi air
pressure. Watch for signs of air bubbles.
The carrier air compressor assembly is a single
Remove cylinder head from water and
acting, reciprocating two cylinder type. The rated
disconnect air hose.
capacity is 71/4 cubic feet per minute at 1,250 rpm. The
Inspect the inlet valves and seats. If inlet
minimum oil pressure required at engine idling speed is
valves are grooved deeper than 0.003
5 pounds per square inch and at minimum governed
inch where they contact the seat, they are
engine speed is 15 pounds per square inch. The
compressor runs continuously while the engine is
Inspect the cylinder bores. If they are
running, but the actual compression of air is controlled
scored or out-of-round more than 0.002
by the governor, which, acting in conjunction with the
inch, or tapered more than 0.003 inch, the
unloading mechanism in the compressor cylinder block,
cylinder block is defective. Clearance
starts the compression of air by loading the compressor
between pistons and cylinder bores should
when the pressure in the air brake system reaches the
be between 0.002 and 0.004 inch.
Inspect the fit of the piston ring gap and
lubricated by oil from the engine crankcase and is
the fit in the piston grooves. The gap
cooled by coolant from the engine.
clearance is 0.007 to 0.019 inch and the
groove clearance is 0.0015 to 0.0030
315. Carrier Air Compressor Assembly Removal
Inspect the clearance of wrist pin. The
a. Removal. Remove the carrier air compressor
wrist pin to the connecting rod bushing
clearance should not exceed 0.0015 inch.
Disassemble the carrier air
Clearance between the connecting rod
compressor assembly in numerical sequence as
must be less than 0.003 inch or more than
0.021 inch after rebuilding compressor
316. Carrier Air Compressor Assembly Cleaning,
rising insert type rods.
Inspection, and Repair
Inspect the crankshaft journals, if they are
a. Cleaning. Clean all parts with an approved
more than 0.002 inch out-of-round or
cleaning solvent and dry thoroughly.
b. Inspection and Repair.
(1) Inspect all parts for excessive wear and
After installing new discharge valves,
springs, and capnuts, the discharge
(2) Plug all holes in the cylinder head except
one and insert air hose. Immerse cylinder