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SD-03-4516

Bendix

SR-5

™

Trailer Spring Brake Valve

FIGURE 1 SR-5

™

TRAILER SPRING BRAKE VALVE

*SHOWN WITH OPTIONAL ANTI-COMPOUNDING COVER

SR-5

™

VALVE

IDENTIFICATION

HOLE

1/4” NPT TRAILER

SERVICE

1/4” NPT

TRAILER SUPPLY

EXHAUST

COVER*

1/4” NPT

SERVICE

RESERVOIR

(2)

3/8” NPT

DELIVERY (4)

1/2” OR 3/4” NPT

SPRING BRAKE

RESERVOIR

PRESSURE

PROTECTION

VALVE

DESCRIPTION

The SR-5

™

valve is a reservoir-mounted trailer valve that can

control up to four spring brake actuators during parking or

emergency applications. It has the following capabilities:

• Automatically applies trailer spring brakes in the event of

a breakaway or trailer supply line failure.

• Protects trailer reservoir(s) air pressure in the event of a

breakaway or trailer supply line failure.

• Allows no automatic trailer spring brake application with

air pressure loss in trailer reservoir(s).

• Allows the trailer spring brakes to be applied and released

repeatedly with a failed trailer reservoir(s):

• Optional anti-compounding-prevents an overriding service

brake signal while the trailer supply line is at atmospheric

pressure.

• Does not allow service system charging if a failure occurs

in the parking brake circuit.

PORTS

1 - 1/2" or 3/4" NPT Spring Brake Reservoir Mounting

(SPR BK RES)

1 - 1/4"-18 NPT Trailer Supply (TRL SUP)

1 - 1/4"-18 NPT Trailer Service (TRL SER)

4 - 3/8"-18 NPT Delivery (DEL)

2 - 1/4"-18 Service Reservoir (SERV RES)

1 - Exhaust (EXH)

The SR-5

™

valve appears very similar to the SR-2

™

valve.

Both valves consist of a die-cast aluminum body and cover,

pressure protection valve, and reservoir-mounting nipple.

However, Figure 1 notes the distinguishing characteristic of

the SR-5

™

valve–a hole drilled into the flat surface between

the pressure protection valve and the body.

Summary of content (9 pages)

PAGE 1
SD-03-4516 ® Bendix® SR-5™ Trailer Spring Brake Valve PRESSURE PROTECTION VALVE 1/4” NPT SERVICE RESERVOIR (2) SR-5™ VALVE IDENTIFICATION HOLE COVER* 1/4” NPT TRAILER SUPPLY 3/8” NPT DELIVERY (4) 1/4” NPT TRAILER SERVICE FIGURE 1 EXHAUST 1/2” OR 3/4” NPT SPRING BRAKE RESERVOIR SR-5™ TRAILER SPRING BRAKE VALVE *SHOWN WITH OPTIONAL ANTI-COMPOUNDING COVER DESCRIPTION PORTS The SR-5™ valve is a reservoir-mounted trailer valve that can control up to four spring brake actuators during parking or emerg
PAGE 2
TRAILER SERVICE SERVICE/SPRING BRAKE RESERVOIR SERVICE/SPRING BRAKE RESERVOIR SERVICE RELAY VALVE SR-5™ VALVE TRAILER SUPPLY TWO-TANK SYSTEM TRAILER SERVICE SR-5™ VALVE SERVICE/SPRING BRAKE RESERVOIR SERVICE RELAY VALVE TRAILER SUPPLY ONE-TANK SYSTEM FIGURE 2 TYPICAL SYSTEM SCHEMATICS WITH SR-5™ TRAILER SPRING BRAKE VALVE 2
PAGE 3
TRAILER SERVICE CHECK VALVE D TRAILER SERVICE RES. CHECK VALVE B SERVICE RELAY VALVE PASSAGE A SERVICE/SPRING BRAKE RESERVOIR CONNECTION TRAILER SUPPLY CONTROL PISTON EXHAUST DELIVERY SPRING BRAKE CHAMBER FIGURE 3 CHARGING BELOW 70 PSI OPERATION CHARGING BELOW 70 PSI (SEE FIGURE 3) Air flows through the trailer supply line, enters the SR-5™ valve trailer supply port, and moves the control piston. The control piston contacts the control inlet/exhaust valve, sealing off the piston’s exhaust passage.
PAGE 4
TRAILER SERVICE TRAILER SERVICE RES. PRESSURE PROTECTION VALVE C CHECK VALVE D CHECK VALVE B SERVICE RELAY VALVE PASSAGE A SERVICE/SPRING BRAKE RESERVOIR CONNECTION TRAILER SUPPLY CONTROL PISTON EXHAUST SPRING BRAKE CHAMBER FIGURE 5 PARK APPLICATION PARK APPLICATION (SEE FIGURE 5) PARK RELEASE WITH TRAILER CHARGED To park the trailer, either the trailer air supply valve or the system park control valve (in the tractor) is actuated. This vents the trailer supply line.
PAGE 5
TRAILER SERVICE CHECK VALVE F ANTI-COMPOUNDING LINE SERVICE/SPRING BRAKE RESERVOIR SERVICE CONNECTION RELAY VALVE CHECK VALVE E TRAILER SUPPLY EXHAUST DELIVERY SPRING BRAKE CHAMBER FIGURE 7 OPTIONAL ANTI-COMPOUNDING Note that pressure protection valve C will open if trailer supply air is greater than 70 psi. But check valves B and D will not open unless release pressure from the tractor exceeds trailer reservoir pressure.
PAGE 6
TRAILER SERVICE TRAILER SERVICE RESERVOIR PRESSURE PROTECTION VALVE C CHECK VALVE B SERVICE RELAY VALVE SERVICE/SPRING BRAKE RESERVOIR CONNECTION TRAILER SUPPLY EXHAUST SPRING BRAKE CHAMBER FIGURE 8 FAILED TRAILER RESERVOIR FAILED TRAILER RESERVOIR (SEE FIGURE 8) Should trailer reservoir pressure be lost, trailer service braking is no longer available. Pressure protection valve C will close at approximately 70 psi (minimum), retaining air pressure in the trailer supply line.
PAGE 7
8. Use only genuine Bendix ® replacement parts, components and kits. Replacement hardware, tubing, hose, fittings, etc. must be of equivalent size, type and strength as original equipment and be designed specifically for such applications and systems. 9. Components with stripped threads or damaged parts should be replaced rather than repaired. Do not attempt repairs requiring machining or welding unless specifically stated and approved by the vehicle and component manufacturer. 10.
PAGE 8
FIGURE 9 - EXPLODED VIEW 8 13 22 14 21 PIPE PLUG 20 3 1 19 17 18 15 2 16 23 10 24 25 VALVE BODY 5 4 8 12 17 PIPE PLUG 18 9 11 7 6
PAGE 9
DISASSEMBLY ASSEMBLY The following procedure is for reference only. Always have the appropriate maintenance kit on hand, and use its instructions in lieu of those presented here. Refer to Figure 9 throughout the procedure. Before assembling the SR-5™ valve, lubricate all o-rings, o-ring grooves, piston bores, and metal-to-metal moving surfaces with Bendix silicone lubricant BW-650-M piece number 291126. 1. Remove the four screws(1) that secure spring retainer(2) to the valve body.