Bendix Air Brake Handbook

5/21/2018 Bendix Air Brake Handbook

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The Air Brake Handbook

2004 Bendix Commercial Vehicle Systems LLC All Rights Reserved


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1www.bendix.com 1-800-AIR-BRAKE (1-800-247-2725)

The Air Brake Handbook

2004 Bendix Commercial Vehicle Systems LLC All Rights Reserved


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Device Index

Device Index

AA-18Controller Assy. . . . . . . . . . . 42

Actuators . . . . . . . . . . . . . . . . . . . . . 17

AD-2Air Dryer . . . . . . . . . . . . . . . 12AD-4Air Dryer . . . . . . . . . . . . . . . 12

AD-9Air Dryer . . . . . . . . . . . . . . . 12AD-IPAir Dryer . . . . . . . . . . . . . . 12

AD-ISAir Dryer Module . . . . . . . . 12

AD-SPAir Dryer . . . . . . . . . . . . . . 13AF-3In-line Air Filter . . . . . . . . . . 13

Air Disc Brakes . . . . . . . . . . . . . . . . 20ASA-5Automatic Slack Adjuster . 18

BBA-922Air Compressor . . . . . . . . . .8

BA-921Air Compressor . . . . . . . 8, 9BA-922Air Compressor . . . . . . . . . .9

BASICTest Kit . . . . . . . . . . . . . . . . . .9Bendix Modules . . . . . . . . . . . . . . . . 45

BP-1Brake Proportioning Valve . . 22BP-R1Bobtail Proportioning

Relay Valve . . . . . . . . . . . . . . . . . . . . 22BVA-85Brake Valve Actuator . . . . 46

BX-2150Air Compressor . . . . . . . . . 8

CConverter Dolly Brakes . . . . . . . . . 33Cyclone DuraDrainTrailer

Water Separator . . . . . . . . . . . . . . . 13

DD-2Governor . . . . . . . . . . . . . . . . 10DC-4Double Check Valve . . . . . . 14

DD3Safety Actuator . . . . . . . . . . . 17Dryer Reservoir Module . . . . . . . . . 12

DS-2Double Check and StopLight Switch . . . . . . . . . . . . . . . . . . . 14

DuraFlo596 Air Compressor . . . 8, 9

EE-10Brake Valve . . . . . . . . . . . . . . 15

E-10PBrake Valve . . . . . . . . . . . . . 15

E-10PRBrake Valve . . . . . . . . . . . . 15E-10PRRetarder Control

Brake Valve . . . . . . . . . . . . . . . . . . . . 16

E-12, E-15Brake Valves . . . . . . . . 15E-14Brake Valve . . . . . . . . . . . . . . 15

E-6Brake Valve . . . . . . . . . . . . . . . 15E-7Brake Valve . . . . . . . . . . . . . . . 15

E-8PBrake Valve . . . . . . . . . . . . . . 15EC-30ABS/ATC Controller . . . . . 36

EC-60ABS/ATC Controller . . . . . 36ESPFunctionality . . . . . . . . . . . . . . 39

ET-Sand ET-S2Electronic

Throttle/Treadles . . . . . . . . . . . . . . . 46EverFlowModule . . . . . . . . . . . . . . 13

FFD-3Fan Clutch . . . . . . . . . . . . . . 46FD-lFan Clutch . . . . . . . . . . . . . . . 46

IInlet Check Valve . . . . . . . . . . . . . . . 10

Inlet Regulating Valve . . . . . . . . . . . . 10

LLP-2and LP-3Low Pressure

Indicators . . . . . . . . . . . . . . . . . . . . . 11LQ-4Ratio Valve . . . . . . . . . . . . . . 21

LQ-4Ratio Valve . . . . . . . . . . . . . . 21LQ-4Valve . . . . . . . . . . . . . . . . . . . 21

LQ-5Bobtail Ratio Valve . . . . . . . . 22

MM-32and M-32QRModulators . 35MC-30Controller Assy. . . . . . . . . 42

MV-3Dash Control Module . . . . . 29

PPE-4Control Valve . . . . . . . . . . . . . 32

PP-1and PP-2Valves . . . . . . . . . . 24PP-1Control Valve . . . . . . . . . . . . . 34

PP-3Control Valve . . . . . . . . . . . . . 24PP-5Push-Pull Control Valve . . . . 27

PP-7Control Valve . . . . . . . . . . . . . 24

PP-8Control Valve . . . . . . . . . . . . . 24PP-DCPark Control Valve . . . . . . 28

PR-3Reservoir Control Valve . . . . 34

PR-4Pressure Protection Valve . . 14PuraGuardQCOil

Coalescing Filter . . . . . . . . . . . . . . . 13

QQR-1Quick Release Valve . . . . . . 21

QR-1CQuick Release Valve . . . . . 26QR-LInline Quick Release Valve . 21

QRN-2Quick Release Valve . . . . . 21QRVQuick Release Valve . . . . . . . 21

RR-12DCRelay Valve . . . . . . . . . . . . 23

R-12PRelay Valve . . . . . . . . . . . 23, 34R-12Relay Valve . . . . . . . . . . . . . . . 23

R-14

Relay Valve . . . . . . . . . . . . . . . 23R-6Relay Valve . . . . . . . . . . . . . . . . 23

R-7Modulating Valve . . . . . . . . . . . 23

R-8PRelay Valve . . . . . . . . . . . . . . . 23R-8Relay Valve . . . . . . . . . . . . . . . . 23

RD-3Control Valve . . . . . . . . . . . . 27RDU(Remote Diagnostic Unit) . . 44

RE-6NCRelay Emergency Valve . . 34

Reservoirs . . . . . . . . . . . . . . . . . . . . 11RV-1Pressure Reducing Valve . . . . 14

SS-Cam Brakes . . . . . . . . . . . . . . . . . . 19SB-1Spring Brake Actuator . . . . . 17

SC-3Single Check Valve . . . . . . . . . 11

SC-PRValve . . . . . . . . . . . . . . . . . . 13SD-3Roto Safety Actuator . . . . . . 17

SL-4and SL-5Stop LampSwitches . . . . . . . . . . . . . . . . . . . . . . 26

Spring Brake Actuators . . . . . . . . . . 17

SR-2Spring Brake Valve . . . . . . . . . 31SR-4Spring Brake Valve . . . . . . . . . 31

SR-5Spring Brake Valve . . . . . . . . . 31ST-1, ST- 3and ST-4

Safety Valves . . . . . . . . . . . . . . . . . . . 10

SureStroke

Indicator . . . . . . . . . . . 18SV-1Synchro Valve . . . . . . . . . . 27, 34

SV-4Trailer Release Valve . . . . . . . 34System-GuardTrailer Air Dryer . . 13

TTC-2Trailer Control Valve . . . . . . 29TC-6Trailer Control Valve . . . . . . 29

TE-1Trailer Emergency Stop Light 32

TP-3Tractor Protection Valve . . . . 30TP-3DCTractor Protection Valve . 30

TP-4Tractor Protection Valve . . . . 30TP-5Tractor Protection Valve . . . . 30

TR-2Valve . . . . . . . . . . . . . . . . . . . 27TR-3Valve . . . . . . . . . . . . . . . . . . . 27

TR-5Lock Line Control Valve . . . . 32Trailer Control (TC) Valves . . . . . . . 29Tu-Flo550 Air Compressor . . . . . 8, 9

Tu-Flo750 Air Compressor . . . . . 8, 9TW-1, TW-3and TW-6

Control Valves . . . . . . . . . . . . . . . . . 26

TW-11Valve . . . . . . . . . . . . . . . . . . 26

VVision Systems . . . . . . . . . . . . . . . . . 45

WWS-24Wheel Speed Sensors . . . . 35

YYaw Stability . . . . . . . . . . . . . . . . . . . 39


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Handbook Section Index

How to use the Air Brake Handbook

DIN symbols are used in this handbook.

Device Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2Air Brake System General Precautions . . . . . . . . . 4General Precautions . . . . . . . . . . . . . . . . . . . . . . . . 4

Section One: A One-Page Introduction toAir Brake Systems . . . . . . . . . . . . . . . . . . . . . 5

Section Two: The Charging System . . . . 6-14Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6Compressors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7-8Compressor Maintenance Guidelines . . . . . . . . . . . 9Governors and Components . . . . . . . . . . . . . . . . 10Reservoirs and Components . . . . . . . . . . . . . . . . 11Air Dryers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12Air Dryers and Filters . . . . . . . . . . . . . . . . . . . . . . 13Miscellaneous Charging System RelatedComponents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Section Three: The Control System . . . .17-32Dual Circuit Brake Valves . . . . . . . . . . . . . . . . . 15-16Actuators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17Slack Adjusters . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18Foundation Brakes . . . . . . . . . . . . . . . . . . . . . . . 19-20Quick Release, Ratio Valves . . . . . . . . . . . . . . . . . . 21Ratio, Proportioning Valves . . . . . . . . . . . . . . . . . . 22Relay Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23Push-Pull Valves . . . . . . . . . . . . . . . . . . . . . . . . . . . 24Spring Brake Valves . . . . . . . . . . . . . . . . . . . . . . . . 25Lever Operated Control Valves . . . . . . . . . . . . . . 26Miscellaneous Control Valves . . . . . . . . . . . . . . . . 27

Section Four: Tractor/Trailer Parkingand Emergency Systems . . . . . . . . . . . . .28-32Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28-29Dash Control Modules . . . . . . . . . . . . . . . . . . . . . 29Tractor Protection Valves . . . . . . . . . . . . . . . . . . . 30Trailer Spring Brake Valves . . . . . . . . . . . . . . . . . 31-32

Section Five: Trailers/ConverterDolly Brakes . . . . . . . . . . . . . . . . . . . . . . .33-34

Section Six:Antilock Braking Systems (ABS) . . . . 35 - 48ABS Components,Truck andTractor ABS Operation . . . . . . . . . . . . . . . . . . . 35-36Truck and Tractor ABS Operation, ATC . . . . . . . 37Straight Truck Sample Schematic . . . . . . . . . . . . . 38Advanced ABS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39Advanced ABS Operation . . . . . . . . . . . . . . . . . . 40Advanced ABS Features . . . . . . . . . . . . . . . . . . . 40-41Trailer ABS Components and Operation . . . . . . . 42Trailer ABS Operation and Features,PLC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43Troubleshooting ABS . . . . . . . . . . . . . . . . . . . . . 43-44

Section Seven: Miscellaneous commercialvehicle products from Bendix . . . . . . . . .45-46

Section Eight:Air Brake System Fundamentals . . . . . . . . 47Braking Force . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48Leverage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49-50Deceleration . . . . . . . . . . . . . . . . . . . . . . . . . . . 50-51Compressed Air . . . . . . . . . . . . . . . . . . . . . . . . . 51-53Compressed Air Brakes . . . . . . . . . . . . . . . . . . . . . 54S-Cam and Air Disc Brakes . . . . . . . . . . . . . . . . . . 55Air Brake System Balance: Pneumatic Systems . . 56Air Brake System Balance: Mechanical Systems . 57

Section Nine: Air Brake SystemTroubleshooting Tests . . . . . . . . . . . . . . . 58-60

Bendix Videos and Literature . . . . . . . . . . . . . . 61-62

List of Service Data Sheets . . . . . . . . . . . . . . . . . . 63

Sample Schematic . . . . . . . . . . . . . . inside front cover

This nine-section handbook provides an introduction to the use andoperation of Bendix air brake systems and devices.

Components are introduced and shown with typical system diagramsto show where they are used. As new components are introduced and

their function explained, they gradually build up to a completefunctioning air brake system.

Partial system-drawings, throughout the manual, assist in explaining ofthe use of the components. See the front inside cover for an example

of a tractor system schematic in color.


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1. Park the vehicle on a level surface, apply theparking brakes, and always block the wheels.Always wear safety glasses.

2. Stop the engine and remove ignition key whenworking under or around the vehicle. Whenworking in the engine compartment, the engineshould be shut off and the ignition key shouldbe removed. Where circumstances require thatthe engine be in operation, EXTREMECAUTION should be used to prevent personalinjury resulting from contact with moving,

rotating, leaking, heated or electrically chargedcomponents.

3. Do not attempt to install, remove, disassembleor assemble a component until you have readand thoroughly understand the recommendedprocedures. Use only the proper tools andobserve all precautions pertaining to use ofthose tools.

4. If the work is being performed on the vehiclesair brake system, or any auxiliary pressurizedair systems, make certain to drain the airpressure from all reservoirs before beginning

ANY work on the vehicle. If the vehicle isequipped with an AD-ISair dryer system ora dryer reservoir module, be sure to drain thepurge reservoir.

5. Following the vehicle manufacturersrecommended procedures, deactivate theelectrical system in a manner that safelyremoves all electrical power from the vehicle.

6. Never exceed manufacturers recommendedpressures.

7. Never connect or disconnect a hose or linecontaining pressure; it may whip. Never removea component or plug unless you are certain allsystem pressure has been depleted.

8. Use only genuine Bendixreplacement parts,components and kits. Replacement hardware,tubing, hose, fittings, etc. must be of equivalentsize, type and strength as original equipmentand be designed specifically for suchapplications and systems.

9. Components with stripped threads or damagedparts should be replaced rather than repaired.Do not attempt repairs requiring machining orwelding unless specifically stated and approvedby the vehicle and component manufacturer.

10. Prior to returning the vehicle to service, makecertain all components and systems arerestored to their proper operating condition.

11. For vehicles with Antilock Traction Control(ATC), the ATC function must be disabled (ATCindicator lamp should be ON) prior toperforming any vehicle maintenance where oneor more wheels on a drive axle are lifted offthe ground and moving.

Air Brake System General Precautions

IMPORTANT

The systems presented in this manual are intended for illustrativepurposes only and are not intended to be used for actual vehicle piping.

WARNING! PLEASE READ AND FOLLOW THESEINSTRUCTIONS TO AVOID PERSONAL INJURYOR DEATH:

When working on or around a vehicle, the following generalprecautions should be observed at all times.

General Precautions


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Air Supply

The vehicles compressor takes in filtered air, either at

atmospheric pressure from the outside (or already atan increased pressure, from the engine turbochargerin some cases), and compresses it. The compressedair is delivered to the air dryer where water and a smallamount of oil is removed. The air then travels into theair reservoirs (air tanks) - typically delivered to arear brake system reservoir and a front brake systemreservoir as well as any attached trailer reservoirs. Foreach system, the air pressurizes the reservoir and theair hoses all the way to the next control valve, wherethe air pressure remains, ready to be used.

A vehicle may use compressed air for many tasks. Someexamples are: to provide force for braking, to deliver

air to a particular component, to off-load bulk goods,etc.

Normal Braking

When the driver applies the foot brake, a plunger withinthe foot brake valve moves, opening channels withinthe valve that allow the air pressure waiting there topass through and be delivered to the rear and frontbrake systems. The pressure quickly increases in thebrake chambers and applies force to the push rod,transferring the force to the S-Cam or air disc brake.(See page 22 for more about foundation brakes.)Frictional forces slow the wheels and the vehicle comesto a stop. When the brakes are released, the air in the

brake chambers is able to be quickly released and enablethe driver to drive away.

Vehicle Parking

Vehicles are parked using powerful springs which arepart of the spring brake assembly, to engage the brakesand hold the vehicle in position. When the driverprepares to move away and releases the parking brake,the spring force is countered by the introduction of airpressure. Anti-compounding valve features in thesystem design help prevent the application of both thespring and service brakes together.

Antilock Braking Systems (ABS)

Most commercial vehicles use electronic AntilockBraking System (ABS) to help improve braking whenexcessive wheel slip, or wheel lock-up, is detected.BendixElectronic Control Units (ECUs) use patentedtechnology to monitor wheel speeds (on all wheelsequipped with speed sensors) and use ABS modulatorvalves to adjust or pulse the braking force being appliedand released, many times per second, during an ABSevent. ABS typically improves stability and steerability,and also reduces stopping distances on most surfaces.

In addition to the ABS features above, some recent

model ECUs have a drag torque control feature whichreduces driven-axle wheel slip (due to driveline inertia)by communicating with the engines controller andincreasing the engine torque.

Antilock Traction Control

In addition to the ABS function, some Bendix ECUmodels provide an Automatic Traction Control (ATC)feature which can help improve vehicle stability andtraction during vehicle acceleration (at low speeds),and lateral stability while driving through curves.

Electronic Stability Program (ESP*)

Recent BendixABS advances include ESPwhich has

the ability to apply brakes to individual wheel ends, andthe trailer, to counteract the trailer push duringmaneuvers that may lead to loss of control or jackknifeson low to high friction surfaces (snow, rain, asphalt,concrete, etc.)

Roll Stability Program (RSP)

The Bendix Roll Stability Program (RSP), is an all-axleABS solution that helps reduce vehicle speed by applyingall vehicle brakes as needed, reducing the tendency toroll over. RSP focuses on reducing the vehicles speedbelow the critical roll threshold during direction-changing maneuvers such as exit ramps and obstacleavoidance on dry, high friction surfaces.

Emergency Braking

In emergency situations where system air pressure isreduced or lost, government regulations requirevehicles to meet specified stopping distances. As anexample, some straight truck system designs usemodulated parking-brake applications to bring thevehicle to a stop.

Vision Systems

Bendix offers video camera systems that help driversback vehicles up safely, assist drivers with viewing whatis in their blind spots around their vehicles, as well as

infrared XVision

night vision camera systems thatprovide drivers advanced warning of obstacles in theirpathway at night by seeing 3 to 5 times further thantheir standard headlights. All of our camera systemscan be purchased individually to meet drivers specificneeds or can be purchased as a total system to providea complete 360 degree 24/7 video camera system fordrivers.

Section 1: One-Page Introduction

Introduction

*ESP is a registered trademark of Daimler Chrysler.


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Section 2: The Charging System

Governor

Air Dryer

PrimaryReservoirSafety Valve

Air Compressor

SupplyReservoir

SecondaryReservoir

Check Valve

Check Valve

SafetyValve

Low Pressure Indicator

PurgeValve

Drain Valve

Safety valves to protect against excessive pressurein the system in the event that a charging systemcomponent malfunction occurs, e.g. a line blockage

Single check valvesto maintain a one-way flowof air into the reservoirs. This arrangement protectsthe contents from being drained in the event of anupstream loss of pressure

Low pressure indicators to alert the driverwhenever a reservoir has less than a pre-set amountof air available

The charging system consists of: An air compressor

A governor, to control when the compressorneeds to build, or stop building, air for the systemand also to control the air dryer purge cycle

An air dryer, to remove water and oil dropletsfrom the air

Reservoirs(or air tanks) to store air to be usedfor vehicle braking, etc.

Overview

The brake system needs a supply of compressed airbetween a preset maximum and minimum. Thegovernor (along with a synchro valve for the Bendix

DuraFlo 596 air compressor) monitors the air

pressure in the supply reservoir and controls whenthe compressor needs to pump air into the air system(also known as the air build cycle - the compressoris running loaded) and when the compressor shouldsimply turn over without building pressure (runningunloaded). When the air pressure becomes greaterthan that of the preset cut-out, the governor controlsthe unloader mechanism of the compressor to stopthe compressor from building air and also causes theair dryer to purge. As the service reservoir air pressure

Bendix Air Compressors

The air compressor is the source of energy for the airbrake system.

Usually driven by the vehicle engine, the air compressor

builds the air pressure for the air brake system. The aircompressor is typically cooled by the engine coolantsystem and lubricated by the engine oil supply. (Certainmodels have self-lubricated and/or air-cooled versionsavailable.) Note: Air compressor shafts can rotate ineither direction.

The vehicles compressor draws in filtered air, eitherat atmospheric pressure from the outside (or alreadyat an increased pressure, from the engine turbochargerwhere permitted), and compresses it.

Note: Although a typical

three-reservoir system is

shown here, some system

designs do not use a

Supply reservoir.


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Compressors

drops to the cut-in setting of the governor, thegovernor returns the compressor back to building airand the air dryer to air drying mode.

As the atmospheric air is compressed, all the watervapor originally in the air is carried along into the airsystem, as well as a small amount of the compressorlubricating oil as vapor.

The duty cycle is the ratio of time the compressorspends building air to the total engine running time.Air compressors are designed to build air (run loaded)up to 25% of the time. Higher duty cycles causeconditions (such as higher compressor head

temperatures) that affect air brake charging systemperformance. These conditions may require additionalmaintenance and lead to a higher amount of oil vapordroplets being passed along into the air brake system.Factors that add to the duty cycle are: air suspension,additional air accessories, use of an undersizedcompressor, frequent stops, excessive leakage fromfittings, connections, lines, chambers or valves, etc. Seepage 9 for compressor maintenance and usageguidelines. Use the BASICtest (p/n 5013711) wherethe amount of oil present in the air brake system issuspected to be above normal.

The discharge line allows the air, water-vapor and oil-

vapor mixture to cool between the compressor andair dryer. The typical size of a vehicle's discharge line,(see table on page 9) assumes a compressor with anormal (less than 25%) duty cycle, operating in atemperate climate. See Bendix and/or vehicle or airdryer manufacturer guidelines as needed.

When the temperature of the compressed air thatenters the air dryer is within the normal range, the airdryer can remove most of the charging system oil. Ifthe temperature of the compressed air is above thenormal range, oil as oil-vapor is able to pass throughthe air dryer and into the air system. Air dryer inlettemperatures play a key role in air system cleanliness

and air dryer performance. Larger diameter dischargelines and/or longer discharge line lengths can helpreduce the temperature.

The discharge line must maintain a constant slope downfrom the compressor to the air dryer inlet fitting toavoid low points where ice may form and block the

flow. If, instead, ice blockages occur at the air dryerinlet, insulation may be added here, or if the inlet fittingis a typical 90 degree fitting, it may be changed to astraight or 45 degree fitting. For more information onhow to help prevent discharge line freeze-ups, seeBendix Bulletins TCH-08-21 and TCH-08-22. Shorterdischarge line lengths or insulation may be required incold climates.

The air dryer contains a filter that collects oil droplets,and a desiccant bed that removes almost all of theremaining water vapor. The compressed air is thenpassed to the air brake service (supply) reservoir. Theoil droplets and the water collected are automaticallypurged at the dryer when the governor reaches its cut-out setting.

For vehicles with accessories that are sensitive to smallamounts of oil, we recommend installation, downstream

of the air dryer, of a Bendix

PuraGuard

QC

oilcoalescing filter to minimize the amount of oil present.

See the Bendix Advanced Compressor TroubleshootingGuide (BW1971) or the compressors Service Datasheet, available online at www.bendix.com for moreinformation.

Governor

Air Dryer

SafetyValve

AirCompressor

Supply Reservoir

SafetyValve

Discharge Line

PurgeValve

Drain Valve

Optional Bendix

PuraGuard QCOilCoalescing Filter


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7.25 2 Both Y Both

9.5 1 Eng. Y** Water

12 2 Eng. Y Water

12 2 Both Y Both

13.2 2 Eng. Y Water

15.5 2 Eng. Y Water

15.8 1 Eng. Y** Water

16.5 2 Eng. Y Water

24 4 Both Y Both

27 2 Eng. N Water

31.6 2 Eng. N Water

32 4 Eng. Y*** Water

Tu-Flo500 aircompressor

Tu-Flo1000air

compressor



or Tu-Flo750air compressor(exterior viewis the same)



Compressors

BX-2150

aircompressor

BA-921air

compressor

CompressorComparison byDisplacement

Tu-Flo400Compressor

BX-2150

Compressor

Tu-Flo500Compressor

Tu-Flo501Compressor

Tu-Flo550Compressor

Tu-Flo700Compressor

BA-921

CompressorTu-Flo750Compressor

Tu-Flo1000Compressor*

DuraFlo596Compressor

BA-922

Compressor

Tu-Flo1400Compressor*

Cylind

ers

Displ

aceme

ntCFM

@1250

0RPM

Engine/s

elf-

lubric

ateda

vail.?

Turbo

inlet

optio

n?

*Special use.e.g. Tank trailer

pump-off

**Uses InletCheck Valve

***Uses InletRegulating

Valve


Single-Cylinder Compressors Two-Cylinder Compressors

Four-Cylinder Compressors

Wate

r/air-

co

oleda

vail.?

DuraFlo596 aircompressor or BA-922aircompressor (exterior view is

very similar)

For compressor Service Data Sheet directory see pages 63-64.


11/67


Maintenance Schedule and Usage Guidelines

Regularly scheduled maintenance is the single most

important factor in maintaining the air brake charging

system. The table below is an introduction to the

maintenance intervals for air brake charging systems. See

your compressor and/or air dryer Service Data sheet for

more information.

If you are concerned that a compressor may be passing

oil, use the BASICTest Kit: Order Bendix P/N 5013711.

Compressor Maintenance Guidelines

Air DryerMaintenance Schedule

Air Compressor Specd

Discharge Line Length

ReservoirDraining

2

1

3

4

a. Note: Compressor and/or air dryer upgrades are recommendedin cases where duty cycle is greater than the normal range (for

the examples above). For certain vehicles/applications, whereturbo-charged inlet air is used, a smaller size compressor maybe permissible.

b. To counter above normal temperatures at the air dryer inlet,(and resultant oil-vapor passing upstream in the air system)replace the discharge line with one of a larger diameter and/orlonger length. This helps reduce the air's temperature. If

sufficient cooling occurs, the oil-vapor condenses and can beremoved by the air dryer. Discharge line upgrades are notcovered under warranty. Note: To help prevent discharge linefreeze-ups, shorter discharge line lengths or insulation may berequired in cold climates. See Bendix Bulletins TCH-08-21 andTCH-08-22, for more information.

c. With increased air demand the air dryer cartridge needs to bereplaced more often.

Low Air Usee.g. Line haul singletrailer without airsuspension, air overhydraulic brakes.

High Air UseHigh Air Use

(5 or less axles) (5 or less axles) (8 or less axles) (12 or less axles)

Discharge line:6 ft. @ in. I.D. (oil carry-over

control suggestedupgradeb: 9ft. @ 5/8in.)

2Discharge line:9 ft. @ in. I.D. (oil carry-over

control suggestedupgradeb: 12ft. @ 5/8in.)

Discharge line:12 ft.@ in. I.D. (oil carry-over control suggestedupgradeb: 15ft. @ 5/8in.)

Discharge line:15 ft.@ 5/8in. I.D. (oil carry-over control suggestedupgradeb: 15ft. @ in.)

Low Air Use

BendixBA-921air compressor

BendixTu-Flo550 air compressor BendixBA-922 air compressor

Examples of Typical Compressors Specda1 BendixTu-Flo750 air compressor

DuraFlo596air compressor

4

3 Drain Reservoirs Every Month - 90 Days Drain Reservoirs Every Month

Replace Air Dryer Cartridge Every 3 Yearsc Replace Every 2 Yearsc

Use the BASICTest Kit:Order Bendix P/N 5013711

BASICtest acceptable range:3 oil units per month.

Use the BASICTest Kit:Order Bendix P/N 5013711

BASICtest acceptable range:5 oil units per month.

OilOilOilOilOilPassingPassingPassingPassingPassing

Concerns?Concerns?Concerns?Concerns?Concerns?

Compressor with up to 25%duty cycle

(builds air pressure up to 25%of the engine running time.)

e.g. Line haul singletrailer with airsuspension,schoolbus.

Compressor with up to25% duty cycle

e.g. Double/triple trailer,open highway coach/RV,(most) pick-up & delivery,yard or terminal jockey,off-highway, construction,loggers, concrete mixer,dump truck, fire truck.

Compressor with up to

25% duty cycle

e.g. City transit bus,refuse, bulk unloaders,low boys, urban regioncoach, central tireinflation.

Replace Every Yearc

Compressor with less than15% duty cycle

(builds air pressure 15% or lessof the engine running time.)


12/67


Governors and Components

The Governormonitors the air pressure in the supplyreservoir and operates the compressor unloadingmechanism to control whether the compressor buildsair pressure or not.

The BendixD-2governoris an adjustable piston-type valve available preset to a choice of pressuresettings.

The pressure range between the cut-in and cut-outpressure is designed into the governor and is notadjustable. The D-2governor may be direct-mountedto the compressor or remote-mounted as desired.Specialized governors are available for vehicles needinga governor adapted to abnormally high or low

temperatures, as well as a weatherproof model.

The D-2Agovernor is a non-adjustable version of theD-2governor.

The D-2/SV-1 governor module is a specialcombination device used with the BendixDuraFlo

596 air compressor to provide the fast-rising unloadersignal needed by this compressor.

Safety Valves are used in an air brake system toprotect against excessive air pressure buildup and tosound an audible alert. Safety valves are available inboth adjustable (e.g. the BendixST-1valve) and non-adjustable (e.g. ST-3, ST-4valve) styles, in various

pressure settings, and for various port sizes. Maximumservice system air pressure allowed by governmentregulation is typically 150 psi. Various safety valvesettings are used at different points in the charging andtreatment system.

Specifically designed for use in compressors, ST-4

safety valves are installed in an extra compressor headdischarge port, if available, or in the discharge line nearthe compressor, to prevent compressor damage in theevent of discharge line blockage.

An Inlet Regulating Valve(or IRV) is typically usedon multi-cylinder compressors which receive their input

air supply from the pressurized side of the engineturbocharger. The IRV, which is generally mounted tothe compressor inlet, is designed to regulatecompressor inlet pressure to 10 PSI or less. The outletflange of the IRV can be mounted to all Bendix

Tu-Flocompressors except the BendixTu-Flo300compressor. The IRV may not be used in conjunctionwith single cylinder compressors.

Governors and Components

Governors

D-2A

Governor

Inlet Check Valves(or ICV) are used on naturallyaspirated compressors to prevent oil mist from enteringthe inlet line during the unloaded cycle. The inlet checkvalve either mounts to the intake side of thecompressor (and must be used in conjunction with aninlet valve stop or inlet adapter), or may be mountedremotely.

InletCheckValves

InletRegulating

Valve

ST-1, ST- 3and ST-4

Safety Valves

D-2/SV-1

GovernorModule

D-2

Governor

Exhaust Port Shown withbreather valve

installed


13/67


Reservoirs and Components

Reservoirs

are availablein manyconfigurations.

Reservoirs(or air tanks) serve the air brake systemas a storage tank for compressed air. The reservoirsize is selected by the vehicle manufacturer to provide

an adequate amount of air for use by the braking systemand other control devices.

Bendix reservoirs are built in accordance with SAEspecifications and are available in various sizes in bothsingle and double compartment design configurations,and are certified to comply with government regulations(such as FMVSS 121).

Reservoir draining devicesare installed in air brakereservoirs, and allow liquid contaminants collected tobe drained off. Vehicles without air dryers are normallydrained each day. Vehicles which have Bendix desiccantair dryers should be drained every 30-90 days. [Tip:The presence of water may indicate that the air dryer

cartridge may need to be replaced. Other potentialsources of water in the reservoirs are: when shop airhas been used to fill the system, an excessive duty cycle,or excessive air leakage.]

Manual draining devices consist of drain cocks whichrequire manual operation at the point at which theyare installed. Drain cocks are available in various stylesand pipe thread sizes. [Tip: Always drain contentsslowly for best results.]

The BendixDV-2automatic reservoir drain valve isa completely automatic draining device. It is installeddirectly into the end or bottom drain port of the

reservoir and does not require any additional controllines. It is available in either an end-port or bottom-port version, and with or without a (12v or 24v) heater.These are most suitable for systems without a desiccantair dryer.

Single Check Valves

The in-line single check valve allows air flow in onedirection only. Several sizes and configurations areavailable to accommodate various piping arrangements.Single check valves are used in air brake systems toprevent loss of remaining system pressure if anotherreservoir, or hose etc. upstream in the system fails.

For double check valves and pressure protection valves,see page 14.

Low Pressure Indicators

Low pressure indicators are pressure-operated electro-pneumatic switches that are designed to complete an

electrical circuit and actuate a warning light and buzzerfor the driver in the event air pressure in the servicebrake system is below a minimum level for normaloperation. The low pressure indicator is available invarious pressure settings, is not adjustable, and isgenerally used in conjunction with a dash mountedwarning lamp or warning buzzer or both.

DrainCock

SC-3

SingleCheckValves

DV-2Automatic Drain Valve

LP-2LowPressureIndicator

LP-3LowPressureIndicator


14/67


Air DryersThe air dryer is an in-line filtration system that removesboth water vapor and oil droplets from the compressor

discharge air after it leaves the compressor. This resultsin cleaner, drier air being supplied to the air brakesystem, and aids in the prevention of air line andcomponent freeze-ups in winter weather.

Air dryers typically use a replaceable cartridgecontaining a desiccant material and an oil separator.Most of the oil droplets are removed by the oilseparator as the air passes into the air dryer. The airthen moves through the desiccant material whichremoves most of the water vapor.

When the air pressure in the supply air tank reachesthe required level, the governor makes the compressor

stop building air and allows the air dryers purge cycleto begin. During the purge cycle the desiccant materialis regenerated (its ability to remove water is renewed)by a reversal of the saturation process. A small amountof dry air passes back through the desiccant materialand the water that has been collected, as well as any oildroplets collected by the oil separator, are purged outthrough the base of the dryer. It is normal to see asmall amount of oil around the purge valve.

The air dryer end cover is typically equipped with an(12 or 24 volt) integral heating element.

The AD-2, AD-4, AD-9and AD-IPair dryersare designed with an internal storage (purge volume)

of dry air for the purge cycle.

The AD-ISair dryeris an integral purge air dryermodule, which includes a spin-on desiccant cartridge,governor, reservoir and charging valve components ina module. These have been designed as an integratedair supply system. The DRMmodule includes anAD-IS integrated solution air dryer, a reservoir(including a separate purge reservoir section), agovernor, and four pressure protection valves as anintegrated air supply system.

Extended Purge air dryersare designed with anextra amount of air storage internally that is used to

assist in the purge cycle. An example is the AD-IP

EP air dryer.

Several Bendix air dryers are available in specializedDrop-in versions designed especially for air systemsthat use either the Holset (Cummins) Type E or QE aircompressor. These Holset compressors utilize anunusual unloading system that requires that air pressureremain in the discharge line during the entire unloadedcycle of the compressor. For example, the AD-IP

Drop-in version is shown here.

Air Dryers

AD-IS

AirDryer

Module

AD-IP

Air

Dryer

AD-9

AirDryer

AD-2

AirDryer

AD-4 AirDryer

(only availablereman.)

Feedback

Line

Special Discharge PortFitting w/Feedback Line

Connection

AD-IP

AirDryer

(Drop-inversion)

DryerReservoirModule


15/67


EverFlowModule

The EverFlowair dryer module is used for air dryersystems where a vehicle needs a continuous flow ofair, such as for bulk unloaders and central tire inflation.As stated earlier, air dryers need to go through a purgecycle periodically to refresh the moisture-removingdesiccant material. EverFlowair dryer modules have

two air dryers plumbed in parallel that take turnssupplying air, resulting in a continuous, uninterruptedsupply.

System-GuardTrailer Air Dryer

The System-Guard trailer air dryer removes moistureand contaminates from the trailer air system. It isdesigned to protect the trailer air brake system when,for short periods of time, the trailer is pulled by vehicleswithout an air dryer or during times when the trailer isdisconnected from the tractor. It does not take the

PuraGuardFilters

The PuraGuard QCoil coalescing filter (and itspredecessor PuraGuardsystem filter) are for high airuse vehicles such as transit buses and refuse trucks.Installed downstream of the air dryer, these filters usea replaceable filter element mounted within a sumphousing to remove oil aerosols before they can enterthe air system. A drain valve allows periodicmaintenance.

Cyclone DuraDrainTrailer Water Separator

The Cyclone DuraDrain trailer water separator isinstalled in the trailer control and/or supply lines nearthe gladhands. It self-purges liquid contaminates,contains solid contaminants and improves the life ofthe trailer system components.

AF-3In-line Air Filter

The AF-3in-line air filter screens out foreign materialfrom trailer air lines.

Air Dryers and Filters

The AD-SP air dryer uses a small amount of airfrom the supply and front axle (secondary) reservoirsto perform the purge function. Because of thisdifference, the AD-SPair dryer is smaller and lighterthan air dryers that have their purge volume within thedryer canister. An SC-PR Single CheckProtection Valve is used in conjunction with theAD-SPair dryer. The SC-PRsingle check protection

valve is a combination of two separate devices, a singlecheck valve and a pressure protection valve that allowslimited flow in the opposite direction. It serves as ameans of protecting the air pressure in the front axleservice reservoir, since it will only allow its air supplyto be used to help purge the AD-SPair dryer if thepressure is above a certain preset level.

AD-SP AirDryer

(installationuses SC-PR

valve)

SC-PR

Valve

EverFlowModule

place of a dryer normally located on the power unit,but acts as a buffer to remove moisture during wettimes and gives up moisture during dry times.

PuraGuard

system filter(obsolete)

PuraGuard

QCoil

coalescingfilter

System-GuardTrailer

Air DryerCycloneDuraDrain

Trailer WaterSeparator

AF-3

In-line Air Filter

System-Guard

Trailer AirDryer

Trailer Products


16/67


Miscellaneous Charging System Related Components

A double check valveis used in the air system whena single function or component must receive air from,or be controlled by, the higher of two sources ofpressure. An internal disc or shuttle moves in response

to the higher air pressure and allows that air source toflow out of the delivery port. It is recommended thatdouble check valves be mounted so that the shuttle(or disc) operates horizontally.

While not strictly part of the charging system, theDS-2double check valve and stop light switch(shown on this page) performs the function of both astop lamp switch and a double check valve. In somevehicle brake systems, it is used to detect air pressurefrom either brake circuit source, and will operate thestop lamp switch, lighting the stop lamps.

Auxiliary Systems

Vehicle auxiliary components and systems (air actuatedwipers, suspension, etc.) requiring compressed air mustwait until the reservoirs in the charging system havereached a predefined minimum pressure, sufficient forbraking purposes. Once the system has reached thepreset minimum, pressure protection valves open tosupply auxiliary systems.

Pressure Protection Valves

The pressure protection valve is a normally-closedpressure sensitive control valve. These valves can beused in many different applications but are typically usedto protect or isolate one reservoir from another, byclosing automatically at a preset pressure. The valve isalso commonly used to delay the filling of auxiliaryreservoirs until a preset pressure is achieved in theprimary or braking reservoirs. Pressure protectionvalves allow air to be "shared" between two reservoirsabove the closing setting of the valve. The sharingceases when pressure drops below the closing pressureof the valve and the reservoirs are then isolated fromeach other.

The PR-2pressure protection valveis externallyadjustable, while the PR-4 pressure protectionvalve (shown) has a fixed setting. Both valves areavailable in various factory preset pressure settings. The

PR-3

pressure protection valvediffers from thetwo previously mentioned since its design includes acheck valve preventing air return.

Pressure Reducing Valves

The pressure reducing valve is used in variousapplications where a constant set air pressure lowerthan supply pressure is required. A typical applicationis an air operated accessory that requires less thansystem pressure for operation. The RV-1pressure

DC-4

Double

CheckValve

RV-1

PressureReducing

Valve

DS-2

Double Checkand Stop Light

Switch

reducing valve(shown) is available in a wide range ofpressure settings and can be manually adjusted. TheRV-3pressure reducing valve is available withfactory preset pressure settings only and cannot bemanually adjusted.

PressureProtection

Valve

AuxiliaryPR-4

PressureProtection

Valve


17/67


E-10PR

BrakeValve


the vehicle comes to a stop. When the driver removesall force from the brake valve the internal return springsmove back to their original position and allow air inthe valve and delivery lines to vent to atmospherethrough the exhaust port.

The BendixE-6, E-8P, E-10, E-10P, E-12andE-15dual brake valves are typically floor mountedand treadle operated, while the BendixE-7and E-14

dual brake valves are bulkhead mounted, suspendedpedal valves.

Section 3: The Control System

Vehicle parking using push-pull hand operatedvalvesand spring brakes,

Anti-compoundingsystem design to prevent boththe service brakes and the parking brakes beingapplied at the same time, and

Proportioning valves to adjust braking when atractor is not pulling a trailer

The control system typically consists of:

Afoot brake valve and often an additional hand-operated trailer brake control valve

Brake actuators or rotochambers, to changethe applied air pressure into a push-rod forcewhichoperates the foundation brakes (air disc, S-Cam, etc.)

Quick release valves to assist in releasing thebrakes quickly

See the inside front cover for a sample system schematic. The primary (rear) brake circuit

is shown in green and the secondary (front) brake circuit is shown in orange.

E-6

BrakeValve

Note: Brake valvereplacements are

typically orderedwithout the foot pedalcomponents. For illustration,full assemblies are shown here.

Dual Circuit Brake Valves

Dual Circuit Brake Valves

When the driver applies the service brakes using thebrake pedal/treadle, a two-part plunger within the brakevalve moves, closing the valves exhaust and openingpassages within the valve that allow the air pressurewaiting there to pass through and be delivered to therear and front brake systems. The pressure quicklyincreases in the brake chambers and applies force tothe push rod, transferring the force to the S-Cam orair disc brake. Frictional forces slow the wheels and

E-10

BrakeValve

E-7

BrakeValve

E-12

E-15

BrakeValves

E-10P

BrakeValve

E-8P

BrakeValve

E-14

BrakeValve


18/67


Mostly used in the transit (buses/coaches) industry, theE-10PR retarder control brake valve has circuitry

that is used to communicate with retarder systemsinstalled on automatic transmission vehicles - extendingthe life of brake system components.

Hand-operated Brake Valves

For information on trailer control hand-operated valves,see page 29.

Dual Circuit Brake Valves, continued

Vehicle Parking

For vehicle parking, rear brake actuators are designedwith large internal springs that, when engaged, hold aparked vehicle in position. When the driver preparesto move away and releases the parking brake, the springforce is countered by the introduction of air pressureinto a chamber within the spring brake portion of theactuator. A feature called anti-compounding helpsprevent the application of both the spring and servicebrakes together.

(See ABS sectionfor more about

modulators)

Take Air Brake Training with the Experts

Bendix is proud to offer its Air Brake Training School.

The three-day training is tailored to both new and experienced technicians andprovides students with valuable technical knowledge.

Beginning with the fundamentals of compressed air, classes cover the description,

operation and service of major Bendix air brake components of dual air brakesystems, as well as antilock braking.

To enroll, visitwww.bendix.comand visit our training school pages to see thedates of classes offered in your area. Simply download and complete a registration

form, or call 1-800-AIR-BRAKE (1-800-247-2725) and select option 5.


19/67


Actuators

Actuators

Actuators convert the air pressure being applied into amechanical push-rod force acting on the foundationbrakes. Air enters the actuator and pressurizes achamber containing a rubber diaphragm. The air pushesagainst the diaphragm, pushing against the return springand moving the push-plate (and push-rod) forward.Some different types of actuators used in air brakesystems are: brake chambers, rotochambers (withlonger push-rod stroke travel), spring brake actuators(for rear brake axles) and safety actuators (with internallocking mechanisms).

Brake chambersare available in many sizes, providinga wide range of output forces and strokes. Different

size brake chambers are identified by numbers whichspecify the effective area of the diaphragm: a "type 30"brake chamber has 30 square inches of effective area.Some brake chambers with extended push-rod stroketravel are available.

Rotochambers are also available in several sizes,providing a wide range of output forces. The rollingtype diaphragm used in rotochambers provides longlife and gives a constant output force throughout theentire stroke. Rotochambers are frequently used inindustrial applications.

Spring brake actuatorsare composed of separate

air and mechanical actuators in a single housing.Mounted at the wheel of the axle it serves, it functionsas a service, parking and emergency brake. Connectedto the service brake valve, the air applied portion ofthe actuator functions as the service brake. Themechanical portion of the actuator contains a powerfulspring which is compressed by adding air pressure orreleased by removing air pressure. The spring braketherefore contains two actuators which use air pressurein opposite ways. The service actuator requires airpressure to apply the brakes, while the park oremergency actuator uses air pressure to release thebrakes.

The SB-1

spring brake actuator is a pull type,remote-mounted air cylinder that is used as a parkingbrake. Pressurized air in the chamber compresses thesprings when the brake is released. When the air isexhausted, the spring force applies the brake.

The SD-3 roto safety actuator is basically arotochamber with mechanical roller locking mechanismsimilar to that of the DD3 actuator. The SD-3

actuator is generally used on off-highway vehicles, andis piped in various ways to provide service, emergency,

Brake Chamber

Rotochamber

SB-1Spring BrakeSD-3Roto

Safety Actuator

Diaphragms

Spring BrakeChamber

Brake Chamber

ReturnSprings Spring Brake Chamber

ParkingSpring

Yoke

and parking brake functions. It is available in type 36and 50 sizes.

Rarely used today, the DD3 safety actuator (not

shown) was a dual diaphragm brake actuator with threefunctions; service braking, emergency braking andparking. The DD3actuator featured a mechanicalroller locking mechanism for parking and was usedextensively on transit and innercity buses. Because ofits unique locking roller mechanism, the DD3actuatorrequired the use of special control valves such as theTR-2inversion valve.

See page 54 for more about actuators.


20/67


Slack Adjusters

Slack Adjusters

The slack adjuster is the link between a brake chamber oractuator and the S-Cam brake camshaft. Its arm is fastenedto the push rod with a yoke and its spline is installed onthe foundation brake cam shaft. It transforms and multiplies

the force developed by the chamber into a torque whichapplies the brakes via the brake camshaft.

Manual Slack Adjusters

To compensate for the gradual wear on the brake blocklining, slack adjusters are equipped with an adjustingmechanism, which provides a means of adjusting forbrake lining wear. Slack adjuster models are designatedby a number which represents its maximum torque

rating (e.g. a type 20 unit is rated for a maximum of20,000 inch-pounds of torque). Slack adjusters areavailable in various arm configurations, lengths andspline types.

The entire slack adjuster operates as a unit, rotating asa lever with the brake cam shaft as the brakes areapplied or released. The most efficient braking actionis obtained when the slack adjuster arm travel isapproximately 90 degrees and in the recommendedrange of the chamber. Therefore, it is important thatbrake adjustments are made as often as necessary.

Automatic Slack Adjusters

Automatic slack adjusters perform the same functionas the standard unit, except that it automatically adjustsfor lining wear. The Bendix "sure stroke" unique designmonitors brake lining to brake drum clearance, thuseliminating the possibility of over adjustment.

The automatic slack adjuster does not require periodicmanual adjustment, however, the unit does provide formanual adjustment. All Bendix slack adjustersincorporate a grease fitting and/or a tapped hole for alube fitting.

Ideal ASA-5Slack Adjuster Installation

The brake chamber push rod and arm of the slack

adjuster should reach approximately 90 degrees at 1/2the available stroke (mid-stroke) of the chamber. Thechart to the right shows the ASA-5 slack adjusterinstallation tolerance.

Manual SlackAdjuster

ASA-5AutomaticSlack Adjuster

Off-set andStraight Arm

Styles

Bendix offers the SureStroke

Indicator to help slack adjusterinspection and maintenance.

Clamp PinStyle Clevis Pin

Style

X Inches

Arm Length

5.00" 0.75" to 2.00"5.50" 0.75" to 2.00"

6.00" 0.00" to 2.00"

SlackArm

LengthX"

AdjustmentMechanism

LubeFitting

ASA-5SlackAdjuster Installation

Tolerance

Spline

Yoke


21/67


Foundation Brakes

The foundation brake is the actual braking mechanismlocated at each end of the axle. It generally consists ofan air or spring brake chamber (with slack adjuster forS-Cam), and a mechanical brake mechanism includingthe friction material.

S-Cam Brakes

In a cam type foundation brake the pneumatic systemis linked to the foundation brakes by the slack adjuster.The arm of the slack adjuster is fastened to the pushrod of the chamber with a yoke. The spline of theslack adjuster is installed on the brake cam shaft. Theslack adjuster is a lever, converting linear force of thechamber push rod into a torsional or twisting forceneeded to apply the brakes.

When torque is applied to the cam shaft, the "S" shapedcam spreads the brake shoes, forcing the brake lining

into contact with the brake drum stopping the vehicle.Cam brakes are offered in various diameters to meetvehicle braking requirements, with the most commonlyencountered being 16 1/2". The cam brake has a"leading-trailing" shoe design with fixed anchor pointsfor each shoe, opposite the cam end of the shoe.

S-Cam Brake Block and Lining

When S-Cam brakes are applied, the friction materialcontacts the brake drum, producing heat energy. For

optimal performance the heat that is generated mustdissipate rapidly to prevent damage to the frictionmaterial. Therefore the friction material used in thebrake must have the capability of withstanding the heatuntil dissipated through the drum. It takes the rightcombination of ingredients to formulate the frictionmaterial that provides all the desirable characteristics,including long life.

All friction material is identified by a stencil on its edge.This identification code consists of the name of themanufacturer, the formula identification and the frictionclass. The friction class is indicated by two letters.The first letter represents the normal coefficient of

friction, and the second represents the hot coefficientof friction. The numerical range is shown on page 20.

Friction material selection is dependent upon how thedriver uses the brakes, the terrain, vehicle load, etc.The various formulations of material are designed tomeet the needs of these conditions. For example, avehicle performing heavy duty operations on ruggedterrain may benefit by using a "premium" materialdesigned for high heat situations instead of a "standard"material designed for lighter duty operations.

Foundation Brakes

Axle

Brake Chamber

BrakeDrum

Shoe

CAM

Slack Adjuster

S-CAM BRAKE

Spider

Friction Material

BrakeChamber

Brake Pad FrictionMaterial

Rotor

AIR DISC BRAKE


22/67


Foundation Brakes, continued

Brake lining and block differ in thatit takes two brake blocks to line oneshoe while a single brake liningsegment is all that is required to do

the same job. Block is generally 3/4"thick and used on class 8 vehicleswhile lining is 1/2" thick andgenerally used on smaller vehicles.

While it is recommended that amatching set of lining be used oneach wheel, under some conditionsa combination of different liningmaterials may be desirable. If abrake system is marginal, forexample, a full step up to a highergrade lining may give an excessivelylarge capacity. In this event using a

combination of blocks should beconsidered.

Air Disc BrakeCut-away View

Lever

Rotor

EccentricBearingInner

Brake PadOuter

Brake Pad

ActuatingBeam

ActuatorRod

Supply Port

Brake Block Brake Lining

FRICTION CODE CHART

Letter Numerical Range

D over 0.150, but less than 0.250

E 0.250 to 0.350

F 0.351 to 0.450

G 0.451 to 0.550

H Over 0.550

Air Disc Brakes

Bendix air disc brakes are a floating caliper designfor use as a foundation brake on all axles of heavycommercial vehicles and trailers. In terms ofperformance and ease of service, Bendix air disc brakescompared favorably to traditional S-Cam brakes. Theyare available in models with or without a combinationspring brake chamber. Optional wear sensors and wear

diagnostic equipment are available on some models.Bendix air disc brakes convert air pressure into brakingforce. When the foot brake is applied, air from thevehicle brake system enters the service brake chamberthrough the supply port, applying pressure to thediaphragm. The pressure pushes the diaphragm, movingthe pressure plate and pushrod against a cup in thelever. The lever pivots on an eccentric bearing andtransfers motion to the actuating beam. Moving againstreturn spring force, the actuating beam moves twothreaded tubes and tappets, which force the inner brakepad into contact with the brake rotor. Furthermovement of the actuating beam forces the caliper,

sliding on two stationary guide pins, away from therotor, which pulls the outer brake pad into the rotor.The clamping action of the brake pads on the rotorapplies braking force to the wheel.

Releasing the foot brake releases pressure in the servicebrake chamber. With no pressure in the service brakechamber, return springs force the air disc brakes intoa neutral, non-braked position. The non-brakedposition is mechanically controlled by a brake adjustermechanism in the caliper. The caliper contains a brake

adjuster mechanism that turns threaded tubes to set agap (running clearance) between the rotor and thebrake pads. When operated manually with the adjustershaft, the adjuster mechanism sets the systems non-

braked position. The adjuster mechanism also operatesautomatically, whenever the brakes are activated, tocompensate for rotor and brake pad wear and keepthe running clearance constant.

The rotor-friction couple is carefully designed foroptimal performance and durability. It is recommendedthat only approved replacement disc pads or rotors beused to prevent damage to disc brake components (e.g.cracked rotors) or premature or uneven pad wear,which can adversely affect braking performance.

The friction class isindicated by two letters

(e.g. DF). The firstletter represents the

normal coefficient offriction, and the second

represents the hotcoefficient of friction.


23/67


Quick Release, Ratio Valves

Quick Release Valves

The function of thequick release valveis to speedup the exhaust of air from the air chambers. It ismounted close to the chambers it serves. In its standardconfiguration, the valve is designed to deliver withinone psi of control pressure to the controlled device;however, for special applications the valve is availablewith greater differential pressure designed into thevalve.

Several styles of quick release valves are available andare functionally the same. The QRVquick releasevalve is the oldest design and utilizes a die cast metalbody with an internal diaphragm, spring and spring seat.TheQR-1quick release valvealso has a die cast

body and diaphragm, but does not employ a spring orspring seat. The (non-serviceable) QRN-2 quickrelease valveis a nonmetallic version of the QR-1

quick release valve. The QR-L quick releasevalveis an inline device.

QRVQuickRelease Valve

QRN-2QuickRelease Valve

QR-1Quick

Release Valve

QR-L InlineQuick

Release Valve

Ratio Valves

The LQ-4

ratio valvewas designed to replace theLQ-2limiting and quick release valve in the front axledelivery l ine of vehicles meeting governmentregulations, such as FMVSS 121. During normal servicebrake applications, the LQ-4ratio valve automaticallyreduces application pressure to the front axle brakes,however, as brake application pressure is increased thepercentage of reduction is decreased until atapproximately 60 psi (depending upon valve design) full

pressure is delivered. The valve is available with severaldifferent "hold-off" pressures which prevent the frontbrakes from operating until the "hold-off" pressure isexceeded.

The obsolete LQ-3 ratio valve appears identical tothe LQ-4ratio valve with minor differences in portingsize.

LQ-4

Valve

LQ-4

RatioValve


24/67


Bobtail Ratio Valves

The LQ-5bobtail ratio valveis used on the front(steering) axle of tractor air brake systems to reduce

brake application pressure during normal tractor-traileroperation. During bobtail mode (when the tractor isnot pulling a trailer), tractor braking performance isimproved because the LQ-5bobtail ratio valve deliversfull brake pressure to the steering axle.

The LQ-5bobtail ratio valve is designed for tractorsystems only, and it replaces the existing front axlelimiting valve.

Ratio, Proportioning Valves

Air Brake Proportioning Valves

The BP-1 brake proportioning valves are

incorporated into the air systems to improve thecontrollability and reduce the stopping distance ofbobtail operated tractors during braking. The TR-3

valve senses the lack of trailer supply line pressureduring bobtail operation, and controls the BP-1

FRONT and REAR valves. The BP-1FRONT valvereduces application pressure to the front brakes duringtractor trailer operation and returns to full applicationpressure during bobtail operation. The BP-1REARvalve delivers full pressure during tractor traileroperation and reduces application pressure duringbotail operation. Treadle application force, duringbobtail operation, resembles treadle application force,during tractor operation with a loaded trailer.

Both the BP-1FRONT and REAR valve are identicalin appearance to the LQ-5valve, however they arenot interchangeable. A metal tag identifies the BP-1

valve.

Brake Proportioning Relay Valves

The BP-R1bobtail proportioning relay valveisa combination of two valves in a single housing. Thelower portion contains a "standard" service brake relayvalve, which functions as a relay station to speed upbrake application and release. The upper portionhouses a brake proportioning valve which reduces

normal service brake application pressure when thetractor is not towing a trailer (bobtail operation). Thecontrol port on the BP-R1valve is connected to thetrailer supply valve delivery and signals bobtailoperation.

BP-R1Valve

BP-1Valve

Tag Indicates ValveName and Usage

LQ-5

Bobtail RatioValve

PP-7

Valve

LQ-5

Valve


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Relay Valves

Relay valvesare primarily used on vehicles to applyand release rear axle(s) service or parking brakes.

When the driver applies the brakes, air travels throughthe delivery (in this case signal) line to the relay valveand moves an internal piston down. This closes theexhaust and opens the delivery of air to the brakes.The primary benefits of using a relay valve is that thehigh capacity of air needed for braking is delivereddirectly and does not have to travel up to the brakevalve and then all the way to the brakes. The brakeforce is adjustable and when released the relay valveexhausts to atmosphere. Relay valves are generallymounted close to the chambers they serve and areavailable in both remote and reservoir mount designs.The inlet/exhaust valve cartridge can be replacedwithout line removal.

In order to design braking systems with good braketiming, that is, where brake application occurs in thecorrect sequence, some models of relay valves areavailable in multiple crack pressures. The crackpressure value for a particular valve is varied by theuse of different strength return springs within the valvewhich the air pressure signal must overcome beforeair begins to be delivered to the brake chambers.

TheR-8and R-14relay valvesboth incorporatean integral double check valve with a balance portconnection which provides both an anti-compoundingor quick exhaust feature depending upon vehicle

application. The anti-compound feature is used whenthese valves are used to control spring actuated parkingfeatures.

R-7Modulating Valve

The R-7Modulating Valve is used in dual circuitbrake systems and performs four functions; duringnormal operation, it limits hold-off pressure to the spring

R-7

Valve

Spring Brake Actuator

R-7Valve

ParkControlValve

brakes, provides quick release of airpressure from the spring cavity of

the spring brake actuator allowinga fast application of the spring brakeactuators, modulates spring brakeactuator application should a failureoccur in the service brake systemand prevents compounding ofservice and spring forces.

R-12DC

Relay Valve(Straight

trucks)

R-12P

Relay Valve(0 crack pressure for

long wheelbase trailersand dollies)

R-8P

Relay Valve(0 crack pressure for

long wheelbase trailersand dollies)

R-14Relay Valve

(Anti-

compounding)

Relay Valves

R-12

Relay Valve

R-6

Relay Valve

R-8

Relay Valve(Anti-compounding,frame or reservoir mounted)


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Push-Pull Valves

Spring

BrakesS

D

E

E

D

SPP-1

Valve

PP-8

ControlValve

Push-Pull Control Valves

Push-pull control valves are most often mounted

on the vehicle dash board and are used for a variety ofcontrol applications. The PP-1and PP-2valves arepressure sensitive, normally closed, on/off controlvalves which automatically return to the exhaust(button out) position when supply pressure is belowthe required minimum. They may be manually operatedto either position when pressure is above the requiredminimum. Pressure settings and button configurationand wording may vary, depending on application.

The PP-1control valveis commonly used to controlparking and emergency brakes. This valve was alsoused in conjunction with the TP-2tractor protectionvalve in pre-FMVSS 121 single circuit tractor air systems.

Unlike most other push-pull control valves, the PP-8

is nonautomatic, and will remain in the applied (buttonin) position regardless of delivery or supply pressure.The PP-8control valve is commonly used to controlthe tractor brakes only in the (FMVSS 121-compliant)dual system.

The PP-3control valveis primarily used to controlthe TP-3tractor protection valve in pre-FMVSS 121tractor systems. It features a tripper piston whichprevents manual override of the emergency applicationof trailer brakes.

Trailer Supply Valve (Tractor Protection

Control)The PP-7 push-pull control valve is a pressuresensitive, on/off control valve which will automaticallyreturn to the exhaust (button out) position when supplypressure is below the required minimum. It may be

PP-1

ControlValve

manually operated to either position whenpressure is above the required minimum. Buttonconfiguration and wording may vary dependingon application. The automatic exhaust pressureis 40 psi.

The PP-7valve is used to control the tractorprotection system and is generally identified asthe trailer air supply valve. The valve employs anair operated interlock in the lower body whichwill apply the trailer brakes when the tractor

spring applied parking brakes are applied. Theinterlock insures that the tractor parking brakecan not be applied without the trailer parkingbrakes also being applied. Normally this actionwill not affect the position of the PP-7 valvebutton. The interlock of tractor and trailerparking is a requirement of governmentregulations (e.g. FMVSS 121).

PP-7

ControlValve

PP-3

ControlValve

RD-3Valve(See Page 27)


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Spring Brake Valves

The SR-1spring brake valve is used in dual circuit

brake systems and serves two functions; during normaloperation, it limits hold-off pressure to the spring brakesto 90 or 95 psi. If a loss of pressure occurs in the rearservice brake service supply, the valve will provide amodulated spring brake application, proportional to thedrivers service braking pressure delivered to the frontaxle.

The BendixSR-7spring brake modulating valveis used in dual air brake systems with spring brakeactuators. It provides a rapid application of the springbrake actuator when parking, modulates the springbrake actuator application (using the dual brake valveshould a primary failure occur in the service brakesystem) and prevents compounding of service andspring forces.

Simple Spring Brake Anti-compound System

General Operation

Brake compounding can occur in a spring brake parkingsystem due to the direct in-line arrangement of boththe spring chamber and brake chamber. It occurs inunprotected systems when parking AND service brakeapplications are made at the same time. An exampleof this situation occurs when a vehicle is parked on asteep incline; the driver holds the service brakes applied

(preventing the vehicle from rolling backward), thenactuates the park control which "sets" or applies thespring brakes. For a brief time, the air applied servicebrakes and the mechanical spring brakes both exert abraking force on the slack adjusters and foundationbrakes. The forces of the spring and air applicationsare additive and can cause damage to the foundationbrake components (cam shaft splines, shoes, drum, etc.)and/or slack adjuster. An anti-compounding system isespecially important in protecting the adjustingmechanism of automatic slack adjusters from damagecaused by over-torque that occurs during acompounded application of the brakes.

Anti-compounding prevents the simultaneousapplication of both the air and spring brakes by directingapplication air to the spring brakes when both areapplied at once. In the simple anti-compoundingschematic shown here, the double check valve allowsservice application air to apply the service brakes ANDmove into the spring cavity if they are also applied (noair pressure and springs are also applying brakes).

Park ControlValve

Spring Brake

Parking QuickRelease Valve

ServiceBrakeValve

Service QuickRelease Valve

DoubleCheckValve

SR-7SpringBrake Valve

SR-1

SpringBrake Valve

The anti-compounding function of the double checkvalve is built into several air brake devices such as the

SR-7, R-7, R-8, R-14and QR-1Cvalves. Whenthese devices are used in the system, a separate doublecheck valve for anti-compounding is not needed.

It is recommended that the service connection to theanti-compounding device (double check valve) comefrom a point between the service brake chamber andthe first "upstream" service device (in this case a quickrelease valve).

Spring Brake Valves


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Lever Operated Control Valves

Dual Function Quick Release Valve

The QR-1Cvalve has a dual function. It works as aquick release valve for rapid park brake actuation andalso provides anti-compounding, since its double checkvalve prevents simultaneous service and emergencyspring brake applications.

Relay Valve

QR-1C

QuickReleaseValve

QR-1CQuickRelease Valve

Lever Operated Control Valves

The TW-2 and TH-3 valves are identical inappearance (and similar to the TW-1, TW-3 and

TW-4

) except they have two control valves housedin a single body. These two valves differ by the internalcammed control lever, which for the TW-2controlvalve has two lever positions, while the TH-3valvehas three.

The TW-1, TW-3and TW-6series control valvesare manually operated, non-modulating (on - off)control valves used in a wide variety of controlfunctions. The TW-1and TW-3are dash-mounted,lever-controlled valves.

The TW-4 is a manually operated momentary non-modulating control valve commonly used in conjunctionwith air starter systems.

A momentary push-type control valve, the TW-5willdeliver air pressure when the plunger is pushed in andexhaust delivered air when the plunger load is released.A typical application is for control of a differential lock-out.

Stop Lamp Switches

The SL-4and SL-5stop lamp switches are pressure-sensitive electro-pneumatic switches installed in theservice application system. They operate the vehiclestop lamps by completing an electrical circuit andlighting the stop lamps each time a brake application ismade.

See page 14 for the DS-2double check and stop lightswitch.

TW-1Valve TW-2,

TH-3Valve

TW-3Valve

SL-5Switch

TW-11

Valve


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Miscellaneous Control Valves

Inversion valves are air operated control valves, andunlike most control valves are normally open, i.e.

without control pressure the supply is common to thedelivery. The inversion valve is closed by using airpressure from another source and is primarily used inemergency or parking brake systems which operatewith air from an isolated reservoir. The valve is alsoused in interlocking and sequencing applications, wherethe operation of components must take place in specificsequence.

The TR-2 valvewas designed primarily for use inearly DD3safety actuator installations. It is equippedwith a threaded body and nut for mounting. Now usedextensively in DD3actuator systems, it is also used ininterlocking applications. Two mounting holes are

provided.

The TR-3valveis similar in function to the TR-2

valve. A specialized version of the TR-3 valve isavailable with an internal channel connecting supplypressure to control, typically with the external controlport plugged.

The SV-1synchro valve is an air signal-operated,non-graduating (on-off) control valve offered in a varietyof pressure settings and is used to delay or sequencethe action of other pneumatic devices.

When used in non-automatic applications it controls aseparate air system circuit.

The SV-1 valve can also be used as an automaticcontroller (when its supply and control are connected).The valve will open, close and exhaust automatically asthe control and supply pressures rise or fall.

The PP-5 push pull control valve is a pressuresensitive, on - off control valve. It is used in conjunctionwith vehicle torque converter systems, engine speedcontrol systems and some parking brake systems. Inaddition to automatic exhaust and manual control, thePP-5 valve employs a pilot air release feature(interlock) which will allow the valve to be exhaustedby applying a low pressure signal from another control

valve to the PP-5

control port.The RD-3is a manually operated on-off control valve.The valve is spring loaded and will remain in the exhaust(button out) position. Constant manual force isrequired to cause the valve to deliver air. The RD-3

control valve is primarily used as an emergency brakerelease control valve.

TR-2

ValveTR-3

Valve

SV-1

SynchroValve

Miscellaneous Control Valves

PP-5

Push-PullControlValve

RD-3

ControlValve


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Service RelayValveQR-1C

QuickReleaseValve

PP-DCParkControl Valve


Park Control Valves

The PP-DCpark control double check valve is a

push-pull, manually operable on/off valve with an integraldouble check. It is dashboard mounted and providesin-cab control of truck or bus parking brakes. Manuallypushing or pulling the button will release or apply theparking brakes. The integral double check valve allowsthe PP-DCvalve to receive supply air pressure fromeither, or both, the front or rear axle service reservoirs.

The valve is pressure sensitive and automatically movesfrom the applied (over the road position) to the exhaustposition (thus applying the parking brakes) if totalsystem pressure (both front and rear axle reservoirs)drops below 20 to 30 psi.

Section 4: Tractor Parking, Trailer Charging/Parking andEmergency Systems

The tractor/trailer parking and emergency systemtypically consists of:

The tractor parking control system

The trailer parking and emergency system, and

The tractor protection system

See the inside front cover for system schematic. The primary (rear) brake circuit is shown in green

and the secondary (front) brake circuit is shown in orange.

PP-DCParkControl Valve

Tractor/Trailer Parking and Emergency Systems


31/67


The Bendix MV-3 dash control module is a two-button, push-pull control valve housed in a single bodywhich includes a dual circuit supply valve and a checkvalve. The MV-3valve can duplicate the functions ofany existing two or three valve push-pull system andhas the advantage of reduced plumbing.

The MV-3module body, plungers and spools are madeout of a non-metallic, non-corrosive material. All airconnections are at the back of the module with theexception of the optional auxiliary port.

The MV-3

module provides the following functions: Tractor Protection Control.

DeliveryDelivery

Supply#1

ExhaustPort

AuxiliaryDelivery

Port

TractorSpringBrakes

Supply

#2

TractorService

Reservoir #2

TractorProtection

Valve

Tractor ServiceReservoir #1

System Park. Trailer Park Only. Trailer Charge with Tractor Spring Brakes Applied

(Tractor Park Only).

Supply Reservoir Selection. Primary & Secondary Reservoir Connections.

The MV-3 dash control module combines thefunctions of a PP-1control valve and a PP-7trailer

supply valve together into a unified device.

Trailer Control (TC) valves are hand-operated,graduated control valves. The most common use oftrailer control valves is for independent control oftrailer service brakes, however, the valve can be usedfor any application where graduated applicationpressure is required.

These valves use a cam and spring mechanism to controldelivery air pressure and are available with several

different styles of body, clamp and handles. Somemodels are available with self-returning handles. Trailercontrol valves are often used to hold the vehicle whilethe vehicles clutch and accelerator are co-ordinated.The trailer control valve should never be used forparking.

TC-6

TrailerControlValve

Dash Control Modules

TC-2

TrailerControlValve


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Tractor Protection Valves

Tractor Protection Valves

The primary function of tractor protection valves (e.g.the TP-3tractor protection valve) is to protectthe tractor air brake system under trailer breakawayconditions and/or conditions where severe air leakagedevelops in the tractor or trailer. In addition, ineveryday use, the valve is used to shut off the trailerservice and supply lines before disconnecting the tractorfrom the trailer. The valve is usually mounted at therear of the tractor cab and a dash mounted controlvalve.

The TP-3DCtractor protection valve integratesthe functions of the TP-3valve and one double checkvalve. A stop light switch port is provided and is

connected to the delivery of the internal double checkvalve. It also has an internal single check valve thatprevents air pressure from being trapped in the trailerservice line, which prevents brake compounding andminimizes roll away conditions.

The TP-4and TP-5tractor protection valvesare designed to incorporate several pneumatic controlfunctions within a common housing, thereby eliminatingconsiderable interconnection piping.

These include a combination of two double check valvesand a tractor protection valve. With these valves, eitherbrake circuit on the vehicle can be used to apply thetrailer brakes. In addition, when used in conjunction

TP-4TractorProtection Valve

TP-5TractorProtection Valve

TP-3DC

TractorProtection

Valve

with a control valve, it opens and closes the trailerservice and supply lines in the same manner as a tractorprotection valve. The valves also incorporate portingfor the installation of the service stop lamp switch.

The TP-4tractor protection valve, used solely on Ford"L" model tractors, incorporates porting for a frontaxle limiting control on pre-FMVSS 121 vehicles.

The TP-5tractor protection valve also incorporatesa quick release valve for the trailer service line.

TP-3

TractorProtection

Valve

SL-5 Stop Light Switch

PP-7 Trailer Supply

Existing Park Control

Existing BrakeValve

From Rear Axle Service Reservoir

From Front Axle Service Reservoir

To the Tractor Spring Brakes

Supply Hose toTrailer

Service Hose toTrailer

TP-5 Tractor Protection

Hose Couplings

Dummy HoseCoupling

From Double Check (Supplied by Front & Rear Service Reservoir)

Front Axle Delivery

Rear Axle Delivery

D

D

C


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Trailer Spring Brake Valves

Trailer spring brake valves are designed for use in trailerair brake systems.

The SR-4 trailer spring brake valve was an earlierdesign that used a dedicated spring brake reservoir forrelease of the trailer spring brakes. Note: This valve isavailable for service only, due to changes made inFMVSS 121 (superceded by SR-5). All other Bendixspring brake valves use service reservoir air for trailerspring brake release.

Mounted on one of the trailer reservoirs, these valvescontrol both the parking and emergency brake functionsof the spring brakes and use internal pressure

protection and check valves to isolate reservoir failuresto prevent automatic application of the trailer springbrakes. An anti-compound feature is part of thesevalves.

With later government regulations allowing simplifiedsystem plumbing, Bendix developed the SR-5trailerspring brake valve. It also mounts to a reservoir onthe trailer and, like the SR-2& SR-4 trailer springbrake valves, it controls the trailer spring brakes, butunlike these valves, the SR-5trailer spring brake valveuses supply line pressure to release the trailer springbrakes. Because dedicated or isolated reservoirpressure is no longer required by law for spring brake

release, the SR-5 trailer spring brake valve systemneeds only a one reservoir for service volume on singleaxle trailers. Two reservoirs are generally requiredfor service volume requirements on tandem axle

Typical SR-2

Trailer SpringBrake Valve

Tandem AxleTrailer Air

System

SR-4Spring

Brake Valve(Original Design)

SR-4Spring

Brake Valve(Revised Design)


SR-5Spring Brake Valve

Look fordrilled hole

ABS

Controller/Relay

Assembly

Spring BrakeReservoir


trailers. An integral anti-compound feature is part ofthe SR-5 trailer spring brake valve. The SR-5 is a"spring brake priority" trailer valve.

Trailer Spring Brake Valves

ServiceReservoir

ServiceReservoir

Note: The SR-5trailer spring brakevalve looks very similar to theoriginal design of the SR-2 valve.Look for a hole drilled into the flatsurface between the pressureprotection valve and the body forpositive SR-5 trailer spring brake

valve identification.


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Trailer Spring Brake Valves, continued

ABS Controller/Relay Assembly

SR-5TrailerSpring Brake Valve

The TE-1trailer

emergency stop lightswitchis a pressure-sensitive switch to operatethe stop lights in the eventof emergency trailer brakeapplication.

Typical SR-5

Trailer SpringBrake Valve

Tandem AxleTrailer Air

System(Note simplified

system plumbing)

Service

Reservoir

ServiceReservoir

Some System

Designs Use aSingle Two-Compartment

Reservoir

The TR-5lock line control valve is a specialized,pilot operated, non-automatic, on - off control valve,designed primarily for use in off-highway parking andemergency brake systems. It is almost identical inappearance to the SV-1 control valve. Unlike theSV-1control valve, the TR-5contr

Documents

Bendix Air Brake Handbook