TM 5-4310-387-14
from the aftercooler enters the final separator. The final separator removes the condensed oil and water vapor by air
passing through two separate tubes of different lengths within the separator. The accumulated condensate may be
discharged by the separator drain valve. The final safety valve protects the third stage, aftercooler and final separator
from over pressures. The compressed air leaving the final separator flows into the purifier chamber by way of a check
valve. The function of the check valve is to prevent a reverse flow of air from the purifier chamber back into the final
separator whenever the condensate in the separator is drained. such a reverse flow of air could damage the chemicals
in the purifier chamber cartridge. Any accumulated moisture collecting in the purifier chamber may be drained by the
purifier chamber drain valve. This drain valve is also used to relieve any pressure within the purifier chamber so that the
chamber may be opened for cartridge servicing. The pressure maintaining valve prevents passage of air through the
chemicals in the purifier chamber until the pressure rises above about 2000 PSIG (135 BAR). This is done to insure the
purifier operates at peak efficiency. The final pressure gauge and fill pressure gauge indicate the air pressure inside the
purification chamber and the air pressure being delivered to the diver tank block respectively.
1-13. Compressor Lubrication System. The compressor is equipped with a positive pressure lubricating oil system.
The oil pump is driven by a cam which is bolted to the end of the crankshaft. The oil pump supplies oil to a pressure
regulating valve which controls the oil pressure. The pressure regulating valve also controls the oil flow rate to the third
stage cylinder. The surplus oil not required for the third stage is delivered to be base of the second stage cylinder to
provide lubrication for the second stage and the crankshaft. The oil then drains back into the crankcase sump where it is
picked up by the oil pump for recirculation. The first stage is lubricated by an oil vapor drawn from the crankcase into the
intake of the first stage. This high pressure lubrication system insures adequate oil delivery to all wear points resulting in
minimum wear and maximum service life.
1-14. Detailed Principles of Operation for Engine Assembly.
a.
Starting System. A hand crank is connected to the camshaft which in turn is connected to the crankshaft. When
the hand crank is turned the crankshaft rotates at twice the starting crank speed.
b.
Diesel Engine. In the diesel engine, air alone is compressed in the cylinder. After the air has been drawn into the
cylinder through the intake valve during the intake stroke the intake valve closes and the piston rises in the cylinder and
compresses the air. A charge of fuel is sprayed into the cylinder and the heat of compression is sufficient to ignite the
fuel air mixture and force the piston downward on its power stroke. The exhaust valve opens during the pistons upward
travel and allows the exhaust gases to escape. As the piston starts downward again, the exhaust valve closes, the intake
valve opens and the cycle starts again.
c.
Fuel System. The fuel system is comprised of a four quart (3.7 L) fuel tank, fuel filter, fuel pump, and injector.
The fuel tank is located above the fuel pump and fuel is gravity fed to the pump. The fuel filter is located between the
fuel tank and fuel pump and removes dirt from entering the fuel pump. The fuel pump is mechanically driven and
supplies high pressure fuel to the fuel injector. All excess fuel is delivered back to the fuel tank.
d.
Air System. Air enters the engine through an oil bath air cleaner, which is designed to remove foreign matter from
the air. The air is drawn into the engine by the piston when the air intake valve is open.
e.
Cooling System. The cooling system is comprised of a cooling fan and air baffles. The fan is connected to the
flywheel on the end of the crankshaft. When the engine is running the fan provides a flow of air that passes around the
cylinder and cylinder head and removes heat.
1-8
