TRUCK SERVICE MANUAL
With the engine still running make a series of
If the governor is being mounted remotely, it
brake applications to reduce the air pressure and
should be positioned so that its exhaust port points
observe at which pressure the governor cuts in the
down. It should be mounted higher than the compressor
compressor. As in the case of the cutout pressure, the
so that its connecting lines will drain away from the
cut-in pressure should be in accordance with the
governor piece number. Common cut-in pressures vary
between 80100 psi. Never condemn or adjust the
governor pressure settings unless they are checked with
If compressor-mounted type, use a new governor
an accurate test gauge or a dash gauge that is
registering accurately. If the pressure settings of the
Connect air lines to governor. Test governor as
governor are inaccurate or it is necessary that they be
outlined under SERVICE CHECKS.
changed, procedure is as follows.
First, unscrew the cover at the top of the governor.
Next, loosen the adjusting screw lock nut. With a
Clean governor exterior of road dirt and grease
using a good cleaning solvent and brush.
counterclockwise to raise the pressure setting and the
Unscrew the top cover.
screw is turned clockwise to lower the pressure setting.
With a pair of retaining ring pliers remove the
After the adjustment is completed, the adjusting screw
spring assembly retaining ring.
lock nut should be tightened to lock this adjustment.
Remove the adjusting screw and spring assembly.
Remove the lock nut, then the hex-shaped upper
spring seat from the adjusting screw.
Leakage checks on the D2 governor are made at
Remove the pressure setting spring, lower spring
its exhaust port in both cut-in and cutout positions. In the
seat, spring guide and the other lower spring seat from
cut-in position check exhaust port for inlet valve leakage
the adjusting screw.
by applying a soap solution at the port. Leakage could
Remove the exhaust stem and its spring from the
also be past the bottom piston grommet. In the cutout
top of the piston.
position check the exhaust port to determine leakage at
the exhaust valve seat or stem grommet. In this position
With the body in the inverted position tap it lightly
leakage could also be past the upper piston grommet.
and the piston should fall out.
Leakage in excess of a 1" soap bubble in 3
seconds is not permissible in either of the foregoing
Remove the inlet and exhaust valve spring and the
tests. If excess leakage is found, the governor must be
valve from the piston.
repaired or replaced.
Remove the two piston grommets and with a
hooked wire remove the exhaust stem grommet.
Block and hold vehicle by means other than air
Clean or remove the unloader and reservoir port
CLEANING AND INSPECTION
If governor is compressor mounted type,
Clean all metal parts in a good cleaning solvent.
disconnect reservoir air line.
If remote mounted
governor, disconnect both the unloader and reservoir air
Wipe rubber parts dry.
Remove governor mounting bolts, then governor.
Inspect body for cracks or other damage. Be
particularly careful that the body air passages, the filters,
exhaust stem and piston are not obstructed.
If compressor mounted type governor, clean
mounting pad on both compressor and governor block.
Check springs for cracks, distortion or corrosion.
Clean connecting line or lines. Also be sure compressor
unloading port is clear and clean.
Replace all parts not considered serviceable
during these inspections.