breather section.
As a single working unit, the
compression cycle is repeated and the air raised to its
compressor assembly serves to provide high-pressure
ultimate delivery pressure.
air for flamethrower applications. The three cylinder and-
b. Strainer and Relief Valve Assembly. The
piston assemblies are graduated in size. The first stage
has a relatively large bore, while the bores of the second
strainer and relief valve assembly installed in the inlet
and third stages are progressively smaller.
port of the second stage cylinder normally serves only to
strain the interstage air. However, should air pressure
exceed a predetermined valve, the spring-loaded poppet
3-5. Function
is forced away from its seat and air escapes to
atmosphere through the drilled hole in the spring
a. Compressor. When the compressor is in
adjusting plug.
The poppet reseats automatically,
operation, the first stage piston moves toward the
preventing the further escape of air when the internal
crankcase and the space in the cylinder bore between
pressure drops to the normal operating level. Additional
the piston and valve plate is at a reduced pressure. This
protection against inadvertent over-pressurization is
allows ambient air pressure to force the inlet valve away
provided by rupture disks installed in the second and
from the valve plate and air enters the cylinder. At
third stage cylinder caps. The rupture disks, mounted in
conclusion of the intake cycle, the piston reverses
a port drilled through the caps, are designed to burst and
direction and moves toward the cylinder head. The
exhaust air directly to atmosphere in the event of a
intake valve then closes and the air trapped in the
sudden rise in pressure within either of the cylinders.
cylinder is compressed into a smaller volume by the
advancing piston. As the piston approaches the end of
c. Lubrication. The air compressor assembly
its compression stroke, the air pressure is sufficient to
is lubricated by a combination of pressure and mist
overcome the force of the spring holding the exhaust
principles. The complete lubrication system includes an
valve against the valve plate and the compressed air
oil reservoir attached to the bottom of the crankcase, an
flows through the outlet ports through the interstage
oil pump cylinder mounted in the bottom of the reservoir,
connecting tube to the inlet port of the second stage
and an oil pump piston which fits into the cylinder and is
cylinder. Compressor timing is such that the second
driven by the master rod. The oil level in the reservoir is
stage piston is moving toward the crankcase and is
shown on an indicator sight glass mounted on the side of
approaching the bottom of its stroke when compressed
the reservoir. A drain cock located at the bottom of the
air is exhausted from the first stage cylinder. The
reservoir enables the oil to be drained.
During
compressed air enters the second stage cylinder through
compressor operation, oil is drawn into the cylinder on
the strainer and relief valve assembly. The compressed
the piston suction stroke through two holes drilled in the
air flows through the holes drilled in the piston, forces the
cylinder wall. On the piston pressure stroke, .the oil inlet
poppet open, and fills the area of reduced pressure in
holes are covered by the piston preventing the escape of
the cylinder bore between the piston and the exhaust
oil back to the reservoir. The oil trapped in the cylinder is
valve. When the piston reverses direction, the poppet
forced through the hollow bore of the piston, passes
valve is forced closed and the air trapped in the forward
through a drilled hole in the master rod, and lubricates
end of the cylinder is compressed by the advancing
the wear surfaces of the master rod and shaft. The oil
piston. As the second stage piston approaches top dead
thrown from these rapidly moving parts separates into a
center, the pressure of the compressed air in the cylinder
fine mist which fills the interior of the crankcase and
becomes sufficient to override the force of the spring
provides adequate lubrication of the bearings, connecting
holding the exhaust valve closed. The exhaust valv3
links, pistons, and other internal parts. Oil leakage from
opens and the compressed air flows into the interstage
the crankcase is prevented by the use
connecting tube to the compressor third stage where the
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