TM 5-3805-260-24
BASIC BLOCK
CYLINDER BLOCK
The cylinders are a part of the cylinder block.
There are no replaceable cylinder liners. The cylinders
can be machined (bored) up to .040 in. (1.02 mm)
oversize for reconditioning. The cylinders in the block
are at a 900 angle to each other. There are fire main
bearings in the block to support the crankshaft.
CYLINDER HEAD
There is one cylinder head for each side (bank)
of the engine. One intake and one exhaust valve is used
for each cylinder. The valve guides are a part of the
cylinder head and can not be replaced. A valve seat
insert is used for the exhaust valve and can be replaced.
When the seat for the intake valve has been machined to
the limits given in the SPECIFICATIONS, it can be bored
(machined) for a valve seat insert.
PISTONS, RINGS AND CONNECTING RODS
The pistons have two rings which are located
above the piston pin bore. There is one compression
ring and one oil control ring. The oil ring is made in one
piece and has an expansion spring behind it. The
compression ring is also one piece and goes into an iron
band that is cast into the piston.
The piston pin is held in the piston by two snap
rings which go into grooves in the piston pin bore.
The connecting rod is installed on the piston with
the boss on the connecting rod on the same side as the
crater in the piston. The connecting rod bearings are
held in location with a tab that goes into a groove in the
connecting rod.
CRANKSHAFT
The force of combustion in the cylinders is
changed to usable rotating power by the crank - shaft.
The
crankshaft
can
have
either
six
or
eight
counterweights. A gear on the front of the crank - shaft
turns the engine camshaft gear and the engine oil pump.
The end play of the crankshaft is controlled by the thrust
bearing on No. 4 main bearing.
VIBRATION DAMPER
The twisting of the crankshaft, due to the regular
power impacts along its length, is called twisting
(torsional) vibration. The vibration damper is installed on
the front end of the crankshaft. It is used for reduction of
torsional vibrations and stops the vibration from building
up to amounts that cause damage.
The damper is made of a flywheel ring (1)
connected to an inner hub (3) by a rubber ring (2). The
rubber makes a flexible coupling between the fly-wheel
ring and the inner hub.
CROSS SECTION OF VIBRATION DAMPER
1. Flywheel ring. 2. Rubber ring. 3. Inner
hub.
2-18
