Bendix Commercial Vehicle Systems PP-7 TRAILER SUPPLY VALVE - Manual (Page 4)

4
OPERATION - AUTOMATIC EXHAUST (NO
OVER RIDE)
If the driver holds the button of the PP-7 ™ valve in after supply
air pressure has dropped below the 40 P.S.I. automatic pop
out pressure, the control piston will move into the exhaust
position when control port pressure falls below 20 P.S.I.
OPERATION - PARK APPLICATION
During a parking brake application, the park control valve
removes air pressure from the control port of the PP-7
™ valve.
The button of the PP-7 ™ valve remains in.
With air pressure removed from the control port of the PP-7 ™
valve, the control piston moves away from the control inlet
and exhaust valve. The inlet valve seats and the exhaust
passage through the control piston is open. Air at the delivery
port of the PP-7
™ valve is exhausted at the exhaust port of
the PP-7 ™ valve.
FIGURE 6 - PP-7 ™ TRAILER SUPPLY VALVE MANUAL EMERGENCY
FIGURE 7 - PP-7 ™ TRAILER SUPPLY VALVE PARK APPLICATION
#1 Service
Reservoir
#2 Service
Reservoir
Double
Check
Valve
Park
Control
Valve
To
Parking
Brakes
Supply
Port
Plunger
Inlet & Exhaust
Exhaust Vent
Control Inlet
and Exhaust
Exhaust
Port
Control
Piston
PP-7 ™ VALVE MANUAL EMERGENCY
PP-7 ™ VALVE PARK APPLICATION
To Tractor
Protection
Control Port
#1 Service
Reservoir
#2 Service
Reservoir
Double
Check
Valve
Park
Control
Valve
To
Parking
Brakes
Supply
Port
Plunger
Inlet & Exhaust
Exhaust Vent
Control Inlet
and Exhaust
Exhaust
Port
Control
Piston
To Tractor
Protection
Control Port