Chevrolet 70 1969 Series, Shop Manual

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POWER BRAKE 5-59
Figure 27— Adjusting Screw Measurement
and valve spring in piston. N arro w end of inlet valve
spring is against the valve.
7. Insert piston assem bly in bore of governor body.
8. Position adjusting screw and spring assem bly in gov­
ernor body; then using T ru-A rc pliers install the re­
taining ring.
9. Install rubber cover on governor body over adjusting
screw.
10. If previously removed, install two pipe plugs in gov­
ernor body.
11. A fter the governor is installed in shop testing equip­
m ent or in the vehicle, m ake “ Governor Tests.”
G O V ER N O R TESTS AFTER
OVERHAUL
NOTE: This test can be made, using shop test­
ing equipment, or with unit installed in vehicle
as explained following:
OPERATING TEST
S tart the engine and build up air pressure in system.
Observe reading on air pressure gauge in gauge panel
when governor cuts-out, stopping com pression of air by
the com pressor. Refer to “ Governor Specifications” for
proper cut-out pressure and check with reading on the air
pressure gauge, which is located in the cab of the truck.
W ith the engine still running, slowly reduce air pressure
in the system by applying and releasing brakes. Observe
pressure registered by gauge when governor cuts-in and
compression is resum ed. Refer to “ Specifications” at rear
of this m anual, for proper cut-in pressure and check with
reading on the air pressure gauge, which is located in cab
of truck.
Before condem ning or adjusting the governor, be sure
the dash air g a ig e is registering accurately. Use an accu­
rate test gauge to check pressure registered by the dash
gauge. If the pressure settings of the governor are inaccu­
rate, or it is necessary th at they be changed, adjust gover­
nor as described in the following paragraphs:
ADJUSTMENT
1. Unscrew cover at top of the governor.
2. Loosen adjusting screw lock nut.
3. Using a screwdriver, turn adjusting screw counte­
rclockwise to raise pressure settings. T urn adjusting
screw clockwise to lower the pressure settings.
4. W hen adjustm ent is completed, tighten adjusting
screw lock nut.
5. Install cover on the governor.
LEAKAGE TEST
L eakage checks on the governor are m ade at its ex­
haust port in both cut-in and cut-out positions. In the
cut-in position, check exhaust port for inlet valve leakage
by applying a soap solution at the port. L eakage could
also be past the bottom piston grom m et. In the cut-out
position, check the exhaust port to determ ine if leakage is
present at the exhaust valve seat or stem grom m et. In this
position leakage could also be past the upper piston
grom m et.
NOTE: After the leakage test, thoroughly clean
governor of soap.
AIR STRAINER ASSEMBLY
A N D INSTALLATION
(Refer to Figure 5)
If com pressor is to be tested after overhaul, then DO
N O T install air strainer until after com pressor tests.
TYPE WITH PAPER FILTER
1. Install m ounting baffle unit with a new gasket to
com pressor by using two cap screws and lock w ash­
ers.
2. Install new paper filter elem ent into clip-on cover.
3. Install clip-on cover to baffle.
TYPE WITH POLYURETHANE
FOAM FILTER
1. Install new foam filter elem ent into air strainer body.
2. Install air strainer cover to body, using two cross­
recess screws.
3. Install air strainer unit with a new gasket to com pres­
sor by using two cap screws and washers.
CHEVROLET SERIES 70-80 HEAVY DUTY TRUCK SHO P M A N U A L