AIR SYSTEM COMPONENTS
SUBSECTION 9C
REMOVAL. To remove the governor, proceed as follow
OPERATING TEST. The operating test is one of the two
tests which should be performed to check the operation of
1. Block and hold the carrier by a means other than the
the governor when it is suspected that the governor is the
carrier brakes.
cause of en air system malfunction. To perform the oper-
ating test, proceed as follows:
2. Open the drain cocks at the bottom of each air reserve
to drain the air pressure from the system.
Start the engine and build-up air pressure in the air system
and check the pressure registered by the dash gauge at the
3. Remove the reservoir air Iine. Then remove the governor
time the governor cuts out and stops the compression of air
mounting bolts and governor.
by the compressor. The cut out pressure should be 120
pounds (8.27 BARS).
INSTALLATION. To Install a new or rebuilt governor, pro-
ceed as follows:
W ith the engine still running, make a series of brake applica-
tions to reduce the air pressure end observe at what pres-
1. Clean the mounting pad on both the compressor and
sure the governor cuts in the compressor. The cut in pres-
governor block. Also be sure the connecting line and the
sure should be 100 pounds (6.89 BARS).
compressor unloading port are clean and clear.
NOTE
2. Position a new mounting gasket on the compressor, and
install the governor.
Never condemn or adjust the governor pressure set-
ting unless they are checked with an accurate test
3. Connect the air lines to the governor.
gauge or a dash gauge that is known to be registering
accurately.
4. Test the governor as outlined under the topics, Operating
Test and Leakage Test.
If the pressure settings are incorrect, adjust the governor
Cut out and cut in pressure settings as described under the
AIR RESERVOIR (27Z5 and 26Z558)
topic, Adjustment.
DESCRIPTION. A reservoir is a storage tank. The function
of a reservoir is to provide a place to store compressed air
LEAKAGE TEST. The leakage test will determine whether
so there will always be an ample supply available for imme-
the air system malfunction is caused by a worn governor.
diate use in air system operation. It also provides storage
Perform the leakage test as follows:
for sufficient compressed air to permit several brake appli.
cations even after the engine has stopped.
W ith the governor at the cut in pressure, check for leakage
at the inlet valve by applying soap suds at the exhaust port.
A reservoir has no moving parts and could hardly be said to
operate. Nevertheless, things do happen inside the reservoir
W ith the governor at the cut out pressure, check the ex-
which are not always understood. All compressors must
haust valve by applying soap suds to the exhaust port.
pass a certain amount of oil in order to lubricate the cylin-
der wells and piston rings; otherwise, rapid wear or even
If the governor does not function as described, or leakage is
seizing will result. Also, depending on the humidity, the
excessive, it is recommended that the complete governor be
atmosphere entering the compressor contains a certain
replaced. It is possible, however, to overhaul the governor.
amount of water. This oil and water normally passes into
If this is the case, contact the nearest Bendix-Westinghouse
the reservoir in the form of vapor because of the heat gen-
distributor for the necessary overhaul information and
erated during compression. After they reach the reservoir,
parts.
the vapors cool and condense in the form of an oil and
water emulsion and are drained off before entering the air
system proper.
ADJUSTMENT. To adjust the pressure setting of the gover-
nor, first, unscrew the cover et the top of the governor.
This drainage is often referred to as oil but in most cases
Next, loosen the adjusting screw locknut. With a screw-
analysis will show it to be practically all water. An easy
driver, turn the adjusting screw counterclockwise to raise
method Of checking the amount of Oil and water in the
the pressure setting or clockwise to lower the pressure set-
drainage is to put it in a clear glass sealed container and set
ting After the adjustment is completed, tighten the ad-
the container aside for several days. At the end of this
justing screw locknut to lock this adjustment.
9C-2
