NOTE: Read the pressure on the test gauge connected
to the left section of the air tank.
TESTING AND ADJUSTING
3. Push the brake pedal rapidly several times.
If necessary, make an adjustment to the screw to
4. Read the cut-in pressure on the test gauge.
get the correct contact.
5. The correct cut-in pressure is 118 to 122 psi (815 to
With pedal (2) pushed down fully, the plunger on
840 kPa). The correct cutout pressure is 138 to 142
the control valve must have .34 + .03 in. (8.64 f 0.76
psi (950 to 975 kPa).
mm) of travel.
If travel is not correct, loosen the locknut and make
If necessary, make an adjustment to the air compressor
an adjustment to bolt (1) until the travel is correct.
governor as follows:
a. Loosen the locknut on the adjustment screw.
Clearance Adjustment For Control
b. Turn the screw to change the pressure setting. A
Valve For Parking Brake
counterclockwise turn of the screw makes the cut-in
With the safety lever in the PARK position, the
6. If the adjustment screw does not change the cut-in
clearance between the piston of the control valve
pressure, the unloading valves in the air
and plate (1) must be .03 in. (0.76 mm).
If necessary, move the control valve to get the
7. If the cut-in to cutout pressure difference is not
correct, the governor is not working correctly.
Safety Relief Valve
The safety relief valve opens at 175 psi (1210 kPa) and
has no adjustment.
Pedal Adjustment For Service Brakes
1. With brake pedal (2) released, the roller on the
pedal must be just in contact (turn freely) with the
screw on the plunger of the control valve.
1. Plate. A. .03 in. (0.76 mm) clearance.
Rotochamber For Parking Brake
WARNING: When working on the
rotochamber with the safety lever in the brake OFF
position, use extra caution. A sudden loss of pressure
air, caused by moving the safety lever or disconnecting
BRAKE PEDAL FOR SERVICE BRAKES
the line from the control valve to the quick release valve,
1. Bolt. 2. Brake pedal.
will let the rod move suddenly.
With the safety lever in the brake OFF position,
remove the pin from rod end (2).
Push lever (1) up and make an adjustment to the
rod end until the lever has a small amount of free
Install the pin.