SUB-SECTION 9C
AIR SYSTEM COMPONENTS
SUB-SECTION 9C
AIR SYSTEM COMPONENTS
drilled passage in the piston and out the unloader port to
SCOPE
the compressor unloading mechanism. The air, besides
flowing to the compressor unloading mechanism, also flows
This sub-section covers all the valves and devices in the air
around the piston and acts on the additional area of the
system, with the exception of the air compressor and the
piston. This additional force, which results from the larger
brake chambers.
area on the piston, assures a positive action and fully opens
the inlet and exhaust valve.
GOVERNOR (36Z290)
DESCRIPTION. Reservoir air pressure enters the governor
As the system reservoir air pressure drops to the cut in
at the reservoir port and acts on the area of the piston and
setting of the governor, the force exerted by the air pres-
on the inlet and exhaust valve (see Figure 9C-1). As the air
sure on the piston will be reduced so that the pressure-
ressure builds up, the piston moves against the resistance
setting spring will move the piston down. The inlet valve
of the pressure-setting spring. When the reservoir air pres-
will close and the exhaust will open. With the exhaust open,
sure reaches the cut out setting of the governor, the piston
the air at the compressor unloading mechanism will escape
and inlet and exhaust valve move up. The exhaust stem
back through the piston, on through the exhaust stem and
seats on the inlet and exhaust valve, shifting the valve to the
out the exhaust port.
open position. Reservoir air pressure then flows through a
Figure 9C-1. Governor (36Z290)
9C-1
