Basic Engine -807640125

TM 9-2320-312-24-2

Systems Operation Section

Compression ring

The maintenance elements have a normal amount

of inhibitor. The maintenance elements are installed

Intermediate ring

at the first change interval. A sufficient amount of

inhibitor is provided by the maintenance elements

Oil ring

in order to maintain the corrosion protection at an

acceptable level. After the first change interval,

only maintenance elements are installed. In order

All of the rings are located above the piston pin

to provide the cooling system with protection,

bore. The compression ring is a Keystone ring.

maintenance elements are installed at specific

Keystone rings have a tapered shape. The action of

intervals.

the ring in the piston groove that is tapered helps

prevent seizure of the rings. Seizure of the rings is

caused by deposits of carbon. The intermediate

i01855280

ring is rectangular with a sharp lower edge. The

Basic Engine

oil ring is a standard type of ring or a conventional

type of ring. Oil returns to the crankcase through

holes in the oil ring groove.

SMCS Code: 1200

Oil from the piston cooling jets sprays the underside

Cylinder Block And Head

of the pistons. The spray lubricates the pistons

and the spray cools the pistons. The spray also

The cylinder block has seven main bearings. The

improves the piston's life and the spray also

main bearing caps are fastened to the cylinder

improves the ring's life.

block with two bolts for each cap.

The connecting rod has a taper on the pin bore

Removal of the oil pan allows access to the

end. This taper gives the connecting rod and the

crankshaft, the main bearing caps, the piston

piston more strength. The additional strength is

cooling jets, and the oil pump.

concentrated in the areas with the most load. Two

bolts hold the connecting rod cap to the connecting

The camshaft is accessible through the covers

rod. This design keeps the connecting rod width

on the left side of the cylinder block. These side

to a minimum, so that the connecting rod can be

covers support the pushrod lifters. The camshaft is

removed through the cylinder.

supported by bearings that are pressed into the

cylinder block. There are seven camshaft bearings.

Crankshaft

The cylinder head is separated from the cylinder

The crankshaft changes the combustion forces

block by a nonasbestos fiber gasket with a steel

in the cylinder into usable rotating torque which

backing. Coolant flows out of the cylinder block

powers the equipment. A vibration damper is used

through gasket openings and into the cylinder

at the front of the crankshaft to reduce torsional

head. This gasket also seals the oil supply and

vibrations (twist on the crankshaft) that can cause

drain passages between the cylinder block and the

damage to the engine.

cylinder head.

The crankshaft drives a group of gears on the front

The air inlet ports are on the left side of the

of the engine. The gear group can drive any of the

cylinder head, while the exhaust ports are located

following devices:

on the right side of the cylinder head. There are

two inlet valves and one exhaust valve for each

Oil pump

cylinder. Replaceable valve guides are pressed

into the cylinder head. The hydraulically actuated

Camshaft

electronically controlled unit injector is located

between the three valves. Fuel is injected directly

Hydraulic oil pump

into the cylinders at very high pressure. A pushrod

valve system controls the valves.

Gear-driven air compressor

Piston, Rings And Connecting

Power steering pump

Rods

In addition, belt pulleys on the front of the crankshaft

may drive any of the following components:

Two-Piece Pistons

Radiator fan

The two-piece articulated piston consists of an

alloy forged steel crown that is connected to an

Water pump

aluminum skirt by the piston pin. The two-piece

articulated piston has three rings: