TM 5-3805-280-24-2
Engine System Operation and Tests
GENERAL ENGINE DESCRIPTION
105
4
Pistons (N) are made of high-grade cast aluminum
Engines are vertical, in-line, valve-in-head, 4-cycle
alloy with internal ribbing. The skirt is cam ground to
(stroke) diesel engines.
allow for expansion during operation. The piston crown
has a cut-out combustion bowl with a truncated cone
Direct fuel injection is provided by a rotary-type
center. All piston rings (P) are located above the piston
injection pump or an in-line injection pump and 9.5 mm
pin. Two compression rings and one oil control ring are
injection nozzles mounted in cylinder head. The
used. The top compression ring is a keystone shaped
camshaft and injection pump are timed to the
ring located close to the top of the piston for improved
crankshaft by the timing gear train.
engine performance.
Some engines are equipped with a turbocharger. The
The hardened, fully-floating piston pins (O) are held in
turbocharger uses energy from exhaust gases to
place by snap rings. Spray jets (piston cooling orifices)
compress intake air and force it into the combustion
in cylinder block spray pressurized oil on the underside
chamber.
of the piston to lubricate piston pins and cool pistons.
The cylinder block (F) is a one-piece casting. The
The forged steel connecting rods (K) have replaceable
block is available in structural and non-structural
pin bushing and bearing inserts. Some connecting rods
configurations.
have a tapered pin-end while others have a straight
pin-end. Rods and caps have a tongue-and-groove on
The camshaft (E) is timed to the crankshaft (G)
earlier engines and a Precision JointTM on later
through the timing gear train. The camshaft rotates in
engines.
honed bores in the cylinder block. All engines use a
bushing in No. 1 camshaft bore. The camshaft lobes
The engine is equipped with a gear driven oil pump
determine the duration and lift of each valve, and
and full-flow oil filter. The oil filter has an internal
operate the fuel supply pump on rotary-type injection
bypass valve which opens if the filter element
pumps.
becomes restricted. Engines are equipped with an oil
cooler mounted on the right side of the cylinder block.
Intake and exhaust valves (Q) are operated by
The engine is equipped with a pressure regulator valve
camshaft followers (D), push rods (C) and rocker arm
to relieve excessive pressure build-up in the main oil
assembly (T). Valve seat inserts in cylinder head are
gallery, and a bypass valve to prevent oil starvation if
used for intake and exhaust valves.
the oil cooler and filter become plugged.
The crankshaft (G) is a one-piece, heat treated,
Balancer shafts (J) are used on four-cylinder engines
nodular-iron or steel forging which operates in
to reduce vibration. The two shafts rotate on bushings
replaceable two-piece main bearings. Crankshafts are
in cylinder block and are counter-rotating at twice
dynamically balanced and are machined with undercut
engine speed.
and rolled fillets. Two-piece main thrust bearing inserts
are used to control crankshaft end-play.
The engine has a pressurized cooling system,
consisting of radiator, water pump, multi-blade fan, and
Cylinder liners (M) are "wet" sleeve type and are
one or two thermostats.
individually replaceable. Liner packing rings (L) are
used at the lower connection between cylinder block
and liners.
Precision Joint is a trademark of Deere & Company
RG,105,JW7661
1921NOV971/1
13-482
