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 TM 55-1905-219-14-5
3-90.1. VALVE AND INJECTOR OPERATING MECHANISM - MAINTENANCE
INSTRUCTIONS.
a. Three rocker arms are provided for each cylinder; the two outer arms operate the exhaust valves and
the center arm operates the fuel injector.
b. Each set of three rocker arm assemblies pivot on a shaft sup- ported by two brackets. A single bolt
secures each bracket to the top of the cylinder head. The removal of the two bracket bolts permit the rocker
arm assembly for one cylinder to be raised, providing easy access to the fuel injector and the exhaust valve
springs.
c. The rocker arms are operated by a camshaft through cam followers and short push rods extending
through each cylinder head.
d. Contact between each cam follower and the camshaft is done by a hardened roller having a pressed-
in bushing, which runs on a pin in the lower end of the cam follower. Each cam follower operates in a bore in
the cylinder head. A guide for each set of three cam followers is attached to the bottom of the cylinder head to
keep the cam follower rollers in line with the cams and to serve as a retainer during assembly and disassembly
of the cylinder head.
e. A coil spring inside each cam follower is held in place in the cylinder head by a spring seat and spring
seat retainer.
f. The valve and injector operating mechanism is lubricated by oil from a longitudinal oil passage on the
camshaft side of the cylinder head, which connects with the main oil gallery in the cylinder block. Oil from this
passage flows through drilled passages in the rocker shaft bracket bolts, to the passages in the rocker arm shaft
to lubricate the rocker arms.
g. Overflow oil from the rocker arms lubricate the exhaust valves, valve bridges and cam followers. The
oil then drains from the top deck of the cylinder head through oil holes in the cam followers, into the camshaft
pockets in the cylinder block and back to the oil pan.
h. The cam follower rollers are lubricated with oil from the cam followers; oil picked up by the camshaft
lobes and by oil emitted under pressure from milled slots in the camshaft intermediate bearings.
3-1509
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