Table of Contents
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®
®
™
Bendix
SR-7
MOUNTING
STUDS (2)
42
CONTROL
PORT
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.
Spring Brake Modulating Valve
DELIVERY
EXHAUST
4-1
PARK CONTROL
(FROM DASH
VALVE)
2
1
SUPPLY
PORT
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).
2
3
DELIVERY
EXHAUST
41
BALANCE
PORT
1
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Related Manuals for BENDIX SR-7 SPRING BRK MODULATING VALVE
Summary of Contents for BENDIX SR-7 SPRING BRK MODULATING VALVE
- Page 1 APPLICATIONS) FIGURE 1 - EXTERIOR VIEW 2. Modulates the spring brake actuator application using DESCRIPTION the dual brake valve should a primary failure occur in The Bendix ® SR-7 ™ spring brake modulating valve is used in the service brake system.
-
Page 2: Sectional View Of Sr-7
MAIN PISTON CONTROL PISTON DOUBLE CHECK VALVE O-RING SPRING GUIDE CHECK VALVE UPPER BODY COVER RETAINING RING O-RING PARK CONTROL PORT O-RING SPACER IN-LINE SINGLE MAIN PISTON SPRING CHECK VALVE STATIC PISTON SPRING O-RING O-RING O-RING SUPPLY PORT STATIC PISTON SPRING O-RING CHECK VALVE... -
Page 3: System Schematics
PP-DC ™ VALVE 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 ™ SYSTEM FOR A 4X2 OR 6X4 VALVE STRAIGHT TRUCK WITH PP-1 PARKING CONTROL... - Page 4 à CONTROL LINE PRESSURE à BALANCE PORT SECONDARY RESERVOIR CONSTANT PRESSURE CONTROL PORT DELIVERY TO SPRING BRAKES à à INLET / EXHAUST VALVE OPEN FIGURE 5 - CHARGING LESS THAN 107 PSI CHARGING SPRING BRAKE ACTUATORS CHARGING SPRING BRAKE ACTUATORS ABOVE BELOW 107 PSI (FIGURE 5) 107 PSI (FIGURE 6) With the air brake system charged and the parking brakes...
- Page 5 à CONTROL LINE PRESSURE à à BALANCE PORT - PRIMARY CIRCUIT PRESSURE SECONDARY RESERVOIR à CONTROL PORT - SECONDARY CONSTANT PRESSURE CIRCUIT PRESSURE DELIVERY TO SPRING BRAKES à INLET / EXHAUST VALVE SEATED FIGURE 7 - NORMAL SERVICE APPLICATION NORMAL SERVICE APPLICATION (FIGURE 7) PARKING (FIGURE 8) During a service brake application, the valve remains in the Actuating the park brakes (by pulling the dash valve button...
- Page 6 MAIN PISTON MOVES UP à à CONTROL LINE PRESSURE BALANCE PORT - LOSS OF PRIMARY CIRCUIT PRESSURE SECONDARY RESERVOIR CONTROL PORT - SECONDARY CONSTANT PRESSURE à CIRCUIT PRESSURE AIR EXHAUSTS FROM à SPRING BRAKES INLET VALVE SEATED FIGURE 9 - SERVICE APPLICATION LOSS OF PRIMARY CIRCUIT SERVICE APPLICATION WITH LOSS OF AIR IN SERVICE APPLICATION WITH LOSS OF AIR IN PRIMARY CIRCUIT (FIGURE 9)
- Page 7 (Correct spring brake actuator PREVENTIVE MAINTENANCE hold-off pressure is 107 psi nominally.) Important: Review the Bendix Warranty Policy before 3. Place parking control valve in “park” position - gauge performing any intrusive maintenance procedures. A warranty reading should drop to zero promptly. A lag (more than...
- Page 8 If the vehicle is equipped with an AD-IS Tests” section. air dryer system or a dryer reservoir module, be sure to drain the purge reservoir. BW2271 © 2004 Bendix Commercial Vehicle Systems LLC 3/2004. Printed in U.S.A. All rights reserved.