BENDIX SR-7 SPRING BRK MODULATING VALVE User Manual

1
®
Bendix
®
SR-7
™
Spring Brake Modulating Valve
SD-03-9043
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).
MOUNTING
STUDS (2)
EXHAUST
42
CONTROL
PORT
2
DELIVERY
1
SUPPLY
PORT
41
BALANCE
PORT
FIGURE 1 - EXTERIOR VIEW
3
EXHAUST
2
DELIVERY
4-1
PARK CONTROL
(FROM DASH
VALVE)
PIPE PLUG
(INCLUDED IN
QUICK RELEASE
VALVE
APPLICATIONS)

BENDIX SR-7 SPRING BRK MODULATING VALVE Specifications

General

Brand	BENDIX
Model	SR-7 SPRING BRK MODULATING VALVE
Category	Control Unit
Language	English

Summary

DESCRIPTION

Rapid Application for Parking

Provides rapid application of the spring brake actuator when parking.

Modulates Application on Primary Failure

Modulates spring brake application during primary failure in service brake system.

Prevents Force Compounding

Prevents compounding of service and spring brake forces.

OPERATION

Charging Spring Brake Actuators Below 107 PSI

Details air pressure supply to spring brake chambers when system pressure is below 107 PSI.

Charging Spring Brake Actuators Above 107 PSI

Explains valve operation and pressure maintenance above 107 PSI.

Normal Service Application

Describes valve behavior during a normal service brake application.

Parking

Details how actuating park brakes exhausts spring brake air pressure.

Service Application with Loss of Air in Primary Circuit

Explains spring brake modulation during service application with primary circuit air loss.

Service Application with Loss of Air in Secondary Circuit

Describes how secondary circuit air loss affects spring brake pressure maintenance.

Anti Compounding

Explains how the valve prevents compounding of service and spring brake forces.

PREVENTIVE MAINTENANCE

OPERATING TEST

LEAKAGE TEST

SERVICING THE SR-7T™ VALVE

Valve Removal

Procedure for removing the SR-7™ valve from the vehicle.

Valve Installation

Steps for correctly installing the SR-7™ valve onto the frame rail.

Testing the Replacement SR-7T™ Spring Brake Modulating Valve

Outlines operating and leakage tests for a replacement valve.