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FIGURE 2 - TYPICAL 4 X 2 TRUCK SCHEMATIC WITH PP-DC
If primary service reservoir pressure drops below secondary
service reservoir pressure, the double check valve reacts as
shown in Figure 4. It seals the primary service reservoir
supply port and supplies the PP-DC
secondary service reservoir. As is shown, the push-pull button
remains in and the spring brakes remain released.
PARKING BRAKES APPLIED
Figure 5 shows the PP-DC
applied position. This will occur if the driver manually pulls
out the push-pull button or if total system pressure drops to
below 20 to 30 psi.
When the button "pops out," the exhaust seal moves to
open the exhaust port to atmosphere, allowing delivery line
pressure to exhaust. The plunger o-ring moves to seal off
supply pressure. Spring brake hold-off air is exhausted
through the spring brake relay valve.
WARNING! PLEASE READ AND FOLLOW
THESE
INSTRUCTIONS
PERSONAL INJURY OR DEATH:
When working on or around a vehicle, the following
general precautions should be observed at all times.
1. Park the vehicle on a level surface, apply the
parking brakes, and always block the wheels.
Always wear safety glasses.
2. Stop the engine and remove ignition key when
working under or around the vehicle. When
working in the engine compartment, the engine
should be shut off and the ignition key should be
2
PP-DC
™
SUPPLY (PRIMARY
RESERVOIR)
SUPPLY (SECONDARY
RESERVOIR)
™
valve with air from the
™
valve in the parking-brakes-
TO
AVOID
DEL.
VALVE
EXH.
™
PARK CONTROL VALVE
removed. Where circumstances require that the
engine be in operation, EXTREME CAUTION should
be used to prevent personal injury resulting from
contact with moving, rotating, leaking, heated or
electrically charged components.
3. Do not attempt to install, remove, disassemble or
assemble a component until you have read and
thoroughly understand the recommended
procedures. Use only the proper tools and observe
all precautions pertaining to use of those tools.
4. If the work is being performed on the vehicle's air
brake system, or any auxiliary pressurized air
systems, make certain to drain the air pressure from
all reservoirs before beginning ANY work on the
vehicle. If the vehicle is equipped with an AD-IS
air dryer system or a dryer reservoir module, be
sure to drain the purge reservoir.
5. Following
recommended procedures, deactivate the electrical
system in a manner that safely removes all
electrical power from the vehicle.
6. Never exceed manufacturer's recommended
pressures.
7. Never connect or disconnect a hose or line
containing pressure; it may whip. Never remove a
component or plug unless you are certain all
system pressure has been depleted.
8. Use only genuine Bendix
components and kits. Replacement hardware,
tubing, hose, fittings, etc. must be of equivalent
size, type and strength as original equipment and
be designed specifically for such applications and
systems.
SR-1
™
SPRING
BRAKE VALVE
SERVICE
RELAY VALVE
the
vehicle
manufacturer's
®
replacement parts,
ANTI-CMPD.
LINE
QR-1C
™
VALVE
®
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