The first stage cylinder is provided with a silencer cover
1.5.2 The air compressor, gasoline engine, engine fuel
and an intake filter which removes particles of foreign
tank and all components of the pneumatic system are
matter from the ambient air drawn into the compressor.
mounted on an enclosed, two-wheel cart provided with a
A connector nipple on the silencer cover accommodates
tow bar and a cart handle. A recessed instrument panel
a length of hose, enabling intake air to be drawn from a
protected by a hinged door contains the controls and
location remote from the package. Additional filtering is
gages required to regulate and monitor the compressed
provided by a strainer and relief valve assembly
air delivered to the using device from the receiver, and
installed in the inlet port of the second stage cylinder.
also mounts the outlet fittings to which the air hose
couples. Additional hinged doors provide access to the
air hose storage reel and the component assemblies of
NOTE: A strainer and relief valve assembly is
the equipment.
installed in inlet port of third stage cylinder on
Model 3800219 only.
1.5.3
The pneumatic system of the compressor
package assembly is illustrated schematically in Figure
A fine mesh screen installed in the body of the unit traps
1-5. The function of each component assembly used in
solid particles present in the interstage air, and a spring
the system is described in the following paragraphs.
loaded poppet functions as a pressure relief valve to
prevent interstage air pressure from exceeding a
1.5.4 BASIC AIR COMPRESSOR
predetermined value.
1.5.4.1 The air compressor assembly consists of three
1.5.4.3 The intake and exhaust valves used in the first
cylinder and piston assemblies mounted radially on a
stage of the air compressor are spring steel, flapper type
crankcase and pneumatically connected in series. The
valves mounted on opposite sides of a valve plate
pistons are attached to, and actuated by, a master rod
installed between the cylinder head and the cylinder
mounted on a shaft which extends axially through the
proper. The valves are spring loaded to seat against
crankcase. One end of the shaft couples directly to the
concentric rings of holes which are drilled through the
engine crankshaft, and the opposite end extends
valve plate and coincide with the inlet and outlet ports in
through the crankcase endbell and mounts a multiple
the cylinder head.
blade fan which blows cooling air past the cylinders and
interstage connecting tube assemblies. The shaft is ball
1.5.4.4 With the engine operating to drive the
bearing mounted at both ends, and needle bearings are
compressor, and the first st stage piston moving toward
used to minimize mechanical friction and wear at the
the crankcase, the cylinder bore between the piston and
pistons, connecting links and master rod.
valve plate is at a reduced pressure. This allows
ambient air pressure to force the inlet valve away from
1.5.4.2 The three cylinders and piston assemblies are
the valve plate, and air enters the cylinder. At the
graduated in size, the first stage having a relatively
conclusion of the intake cycle, the piston reverses
large bore, while the bores of the second and third
direction and moves toward the cylinder head. The
stages are progressively smaller.
intake valve then closes, and the air trapped in the
cylinder is compressed into a smaller volume by the
advancing piston. As the piston approaches
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