Section X. PRESSURE CONTROL SYSTEM
104. Description
b. Loading Cycle. When the air pressure in the air receiver drops to 90 psi, the unloader pilot shuts off the flow
of air to the suction valve unloaders and causes the suction valves to close. The check and bleed valve
releases air from-the slowdown assembly and temporarily restricts the flow of air from the suction valve
unloaders. The slowdown plunger backs off from the governor lever to increase the speed of the engine.
c. Unloading Cycle. When the air pressure in the air receiver reaches 100 psi, the unloader pilot valve admits
air to the suction valve unloaders thus opening the suction valves. The check and bleed valve admits air to
the slowdown assembly, and the slowdown plunger pushes out against the governor lever to reduce engine
speed to idle.
Caution: Before disconnecting air line tubing or removing pressure control system components,
release all air from the air receiver.
105. Check and Bleed Valve
a. Removal (fig. 41). The check and bleed valve (9) is mounted in the side of the unloader pilot (26). Disconnect
tube assemblies (10 and 25) from the elbows (7) at the top and bottom of the check and bleed valve. Unscrew the valve
from the unloader pilot.
b. Installation (fig. 41). Use reverse order of removal instructions to install the valve.
c. Adjustment (fig. 42). The check and bleed valve provides a time delay which allows the engine to pick up speed
before full load is applied. To increase the time delay, turn the adjusting screw inward (clockwise). To decrease the time
delay, turn the adjusting screw outward (counterclockwise). Do not change the setting of the check and bleed valve unless
absolutely necessary.
106. Control Line Air Filter
a. Removal (fig. 1). Disconnect the tube assembly (4) from the elbow (5) and unscrew the control line air filter (6)
from the unloader pilot (26). Unscrew the elbow from the filter.
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