TM 5-3895-379-23-1
0003
ENGINE SYSTEM
1. General.
a. The engine system provides power for the roller. The engine combines fuel and pressurized air
together and compresses it until ignition occurs, creating mechanical energy. The internal explosion
from the ignited air/fuel mixture pushes the pistons down, turning the crankshaft. The crankshaft is
connected to a pulley and gear on the front of the engine and an output shaft on the rear of the
engine. The pulley forces belts to turn the alternator which keeps the electrical system fully charged
with electricity. The front gear also turns both the power steering hydraulic pump and the fuel
injection pump. The output shaft turns both of the main hydraulic pumps. A cam lobe operates the
fuel lift pump.
b. The engine is turbocharged. When the ignited air is pushed out of the engine, it is routed to the
turbocharger. The exhausted from the engine turns the turbocharger which forces high pressure air
into the engine intake manifold.
2. Turbocharger. The turbocharger forces air into the intake manifold. Exhaust gases coming out of the
combustion chamber force a rotor inside the turbocharger to spin at a very high rate of speed. This rotor is
attached to the intake impeller. The impeller pulls air in from the air filter and forces it into the intake manifold
at a high pressure. The faster the engine runs, the faster the turbocharger spins and the higher the air
pressure it produces.
3. Cylinder Head. The fuel/air mixture is ignited in the combustion chambers of the cylinder head, located
directly over each piston. The intake ports of the cylinder head route air into the combustion chamber while
the injectors supply the fuel to the mixture. The exhaust ports route burned gases out of the engine.
4. Cylinder Head Valves. The cylinder head valves open or close the passages in the cylinder head that allow
flow from the intake manifold or to the exhaust manifold. Valve lash must be adjusted periodically.
5. Combustion Chamber. The combustion chamber is where combustion and ignition occur. Ignition occurs
when diesel fuel or JP-8 is injected into air heated by being compressed by the piston. When the air/fuel is
ignited, it pushes down the piston, turning the crankshaft.
6. Crankshaft. The crankshaft is an eccentric shaft that changes the up-and-down piston motion. The
crankshaft uses this motion at the front of the engine to power the alternator, cooling system, and steering
and fuel pumps.
7. Exhaust System. The exhaust system allows the exhaust gases to be drawn out of the combustion
chamber. The exhaust is pushed out of the cylinder by the piston. It then goes into the turbocharger and
makes it spin. The exhaust is then vented into the air out of an exhaust pipe.
8. Air Filter. The air filter cleans the air entering the engine. The filter consists of a primary element and a
secondary element. Air is pulled through both elements to remove particulates that could damage the engine.
0003-2
03/15/2011Rel(1.8)root(thrywp)wpno(G00006)
