Bendix SR-7 User Manual
®
Bendix® SR-7™ Spring Brake Modulating Valve
MOUNTING
STUDS (2)
4-1
PARK CONTROL
(FROM DASH
VALVE)
42
CONTROL
PORT
EXHAUST
2
DELIVERY
1
SUPPLY
PORT
3
EXHAUST
SD-03-9043
41
BALANCE
PORT
2
DELIVERY
PIPE PLUG
(INCLUDED IN
QUICK RELEASE
VALVE
APPLICATIONS)
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
MAIN PISTON
DOUBLE CHECK
VALVE
CHECK VALVE
COVER
PARK CONTROL
PORT
IN-LINE SINGLE
CHECK VALVE
SPRING
SUPPLY PORT
CHECK VALVE
GUIDE
O-RING
O-RING
O-RING
CONTROL PISTON
SPRING GUIDE
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
BALL CHECK
VALVE
SPRING
FIGURE 2 - SECTIONAL VIEW OF SR-7™ SPRING BRAKE MODULA TING VAL VE USED IN RELA Y V A LVE APPLICA TIONS
O-RING
O-RING
VALVE SEAT
RETAINING RING
DIAPHRAGM
DIAPHRAGM WASHER
EXHAUST
PORT
#10 TORX HEAD SCREW
VALVE RETAINER
SPRING
1/4-20 MACHINE
SCREWS
INLET / EXHAUST
VALVE
LOWER VALVE
GUIDE
RETAINING RING
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
VALV E
™
SYSTEM FOR A 4X2 OR 6X4
STRAIGHT TRUCK WITH
PP-DC PARKING CONTROL
™
™
SR-7 Valve w/single check
Ref: 5010914
FIGURE 3 - SYSTEM SCHEMATIC WITH PP-DC™ PARK CONTROL
™
PP-1
VALV E
SYSTEM FOR A 4X2 OR 6X4
STRAIGHT TRUCK WITH
™
PP-1 PARKING CONTROL
SR-7 valve
w/o single check
™
FIGURE 4 - SYSTEM SCHEMATIC WITH PP-1
™
DC-4
VALVE
™
P ARK CONTROL AND DC-4™ DOUBLE CHECK VALVE
3
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