®
SD-03-9043
Bendix® SR-7™ Spring Brake Modulating Valve
MOUNTING
STUDS (2)
42 CONTROL PORT
EXHAUST
PIPE PLUG
(INCLUDED IN QUICK RELEASE VALVE APPLICATIONS)
41 BALANCE
PORT
4-1
PARK CONTROL
(FROM DASH
VALVE)
2 |
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DELIVERY |
1 |
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2 |
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SUPPLY |
3 |
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PORT |
DELIVERY |
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EXHAUST |
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FIGURE 1 - EXTERIOR VIEW
DESCRIPTION
The Bendix® SR-7™ spring brake modulating valve is used in conjunction with a dual air brake system and spring brake actuator and performs the following functions:
1.Provides a rapid application of the spring brake actuator when parking.
2.Modulates the spring brake actuator application using the dual brake valve should a primary failure occur in the service brake system.
3.Prevents compounding of service and spring forces.
The valve has one park control, one service control, one supply, one balance, four delivery NPTF ports, and an exhaust port protected by an exhaust diaphragm. The valve incorporates two mounting studs for mounting the valve to the frame rail or cross member (where applicable).
1
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MAIN PISTON |
DOUBLE CHECK |
CONTROL PISTON |
VALVE |
O-RING |
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CHECK VALVE |
SPRING GUIDE |
COVER |
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PARK CONTROL
PORT
IN-LINE SINGLE
CHECK VALVE
SPRING
O-RING
SUPPLY PORT 
CHECK VALVE
GUIDE
O-RING
BALL CHECK
VALVE
SPRING
O-RING
O-RING
VALVE SEAT
RETAINING RING
EXHAUST
PORT
DIAPHRAGM
#10 TORX HEAD SCREW
DIAPHRAGM WASHER
UPPER BODY
RETAINING RING
O-RING
O-RING
SPACER
MAIN PISTON SPRING
STATIC PISTON
O-RING
O-RING
STATIC PISTON
SPRING
O-RING
O-RING
O-RING
LOWER BODY
VALVE RETAINER
SPRING
1/4-20 MACHINE
SCREWS
INLET / EXHAUST
VALVE
LOWER VALVE
GUIDE
RETAINING RING
FIGURE 2 - SECTIONAL VIEW OF SR-7™ SPRING BRAKE MODULATING VALVE USED IN RELAY VALVE APPLICATIONS
OPERATION
The operation guidelines shown in this manual represent the relay valve based SR-7™ (refer to system schematic shown in figure 3). A quick release based valve functions similarly to the relay valve based version with the exception
that all air delivered to spring brakes passes through the park control port through the in-line single check valve. The SR-7™ quick release style can be easily identified by the pipe plug in the supply port of the valve.
2
PP-DC™ |
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VALVE |
SYSTEM FOR A 4X2 OR 6X4 |
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STRAIGHT TRUCK WITH |
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PP-DC™ PARKING CONTROL |
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SR-7™ Valve w/single check |
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Ref: 5010914 |
FIGURE 3 - SYSTEM SCHEMATIC WITH PP-DC™ PARK CONTROL
PP-1™ |
SYSTEM FOR A 4X2 OR 6X4 |
VALVE |
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STRAIGHT TRUCK WITH |
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PP-1™ PARKING CONTROL |
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SR-7™ valve |
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w/o single check |
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DC-4™ |
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VALVE |
FIGURE 4 - SYSTEM SCHEMATIC WITH PP-1™ PARK CONTROL AND DC-4™ DOUBLE CHECK VALVE
3
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