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 TM 9-2815-220-24
THEORY OF OPERATION
0004 00
ENGINE COMPONENTS (Continued)
Cylinder and Head Assembly:
Each cylinder assembly is an individually replaceable unit
that consists of a barrel, cooling fin muff, and a cylinder
head. The cylinder barrel, dome, intake and exhaust port
liners are made of steel. The aluminum cylinder head
cooling fins are cast to the steel dome. The cooling fins for
the barrel are machined into an aluminum muff and shrunk
onto the steel barrel. After the cylinder barrel fins are
machined, the head and barrel are electron-beam welded to
form a single unit. Valve guides and seats are shrunk into
place in the head.
The cylinder barrel is tapered at the head end to provide a
straight bore under running conditions. A mounting flange
is machined on the cylinder barrel near the base to provide an attachment of the cylinder to the
crankcase. The cylinder assembly is secured to the crankcase with studs and nuts. An outer
extension of the cylinder head provides mounting for the fuel injection nozzle and encloses a
recess or rocker box, which houses the valves, valve springs, and related parts. Rocker arm
assemblies are held in place by rocker shafts in the cylinder head valve rocker support cover.
The stem of the intake valve and exhaust valve for
each cylinder extends into the rocker box. Three
nested springs, compressed between two retainers and
secured to the valve stem by two cone-shaped locks,
hold each valve to its seat. Each exhaust valve has a
positive valve rotator, which also serves as the lower
spring retainer. Valve clearance adjusting screws
with flat swivel pusher pads are mounted on one end
of the valve rocker arms.
Forged steel valve rocker arms with roller cam-
followers are used. The rollers are hardened and
honed to provide an extremely smooth and permanent
contact surface. Hollow rocker arm shafts and drilled
passages in the rocker arms convey oil to all moving
parts.
A camshaft bearing surface is provided in each cylinder and is split equally between the cover
and the cylinder head. The camshaft bearing surface is bored with the cylinder head valve
rocker support cover in place. Therefore, the covers are not interchangeable and each must
remain as part of a specific cylinder assembly. Identifying numbers are used on cylinders and
covers to prevent mismatching. Each cylinder has replaceable camshaft bearings at the
camshaft bore. Counter bores in the rocker box and rocker support covers accommodate inter-
cylinder rubber hoses and steel flanges which enclose the camshaft between the cylinders.
WP 0004 00-16
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