BENDIX BW1231 データシート

&

6

•   All genuine Bendix replacement parts are manufactured to meet 

original  OE  specifications  to  guarantee  quality,   reliability  and 
proper operating performance.

•   Rely on genuine Bendix replacement parts to keep your air brake 

system operating efficiently.

•   With  thousands  of  authorized  Bendix  parts  outlets  across  North 

America, you’re never far from quality genuine Bendix replacement 
parts.

1

 Equipped with standard Bendix

®

 ABS Antilock Brake System

2

 Equipped with Bendix

® 

ABS and Smart ATC

™

 Traction Control

The color coding of the brake system schematic follows TMC Recommended Practice #423.
Air disc & drum brake actuation combined on a single axle are shown for pictorial purposes only.

CHECKLIST 2

NOTE:  A leak detector or soap solution will aid in locating the faulty component.

1.  Supply lines and fi ttings
2.  Low pressure indicator(s)
3.  Service brake relay valve(s) 
4.  Spring brake relay valve (where applicable)
5.  Dual brake valve
6.  Trailer hand control valve
7.  Parking control valve
8.  System safety valve(s) in the supply reservoir and/or air dryer 
9.  Governor (may be mounted on the air dryer as illustrated, on the compressor, or remotely)
10. Compressor discharge line 

TEST 3

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1. Make  and  hold  brake  application.  When  ignition  power  is  applied,  each 

modulator solenoid is briefl y energized. If the air system is fully charged and the 
service brake pedal is depressed during ignition, the modulator creates a single, 
sharp audible “chuff” of air pressure. The modulators are energized in a certain 
pattern, as follows: right front, left front, right rear, left rear. This test is performed 
only when the vehicle is stationary (if the vehicle moves the chuff test will not 
be performed).

NOTE:  The Bendix

®

 EC-60

™

 controller will perform a PMV chuff test on all installed modulators

in the following order:

  1.  Steer Axle Right PMV
  2. Steer Axle Left PMV
  3.  Drive Axle Right PMV
  4. Drive Axle Left PMV
  5. Additional Axle Right PMV
  6. Additional Axle Left PMV
  7. Drive Axle TCV
 The pattern will then repeat itself.
See appropriate Service Data Sheet for repairs.

TEST 5

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1. Manually  operate  the  park  control,  yellow  button  valve,  and  note  that  parking 

brakes apply and release promptly as the control valve button is pulled out and 
pushed in.

1. Manually operate the tractor protection control valve (trailer supply valve usually 

red octagonal button).  Note that trailer brakes apply and release promptly as the 
control button is pulled out and pushed in.

2. Manually operate system park control (usually yellow diamond button) and note 

all parking brakes (tractor and trailer) apply promptly.

CHECKLIST 5

1.  Dented or kinked lines
2.  Improperly installed hose fi tting
3.  A faulty quick release valve or spring brake control valve
4.  Damaged or improperly installed Spring Brake Chamber and/or Service Chambers
5.  Foundation Brake component binding, improper installation and/or lack of lubrication.

1.  Tractor protection control
2.  Trailer spring brake valve
3.  Damaged spring brake chamber and/or service chambers
4.   Foundation brake component binding, improper installation and/or lack of lubrication

TEST 6

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1.  Drain the front axle or secondary reservoir to 0 psi.

A.  The rear axle or primary reservoir should retain most of its pressure.

B.   On combination vehicles, the trailer air system should remain charged.

C. Tractor and trailer brakes should not apply automatically.

2.  With no air pressure in the front axle reservoir, make a brake application.

A. Rear axle brakes should apply and release when application is released.

B.  On  combination  vehicles  the  trailer  brakes  should  also  apply  and  release 

when application is released.

C. The stop lamps should light and go off when the application is released.

3. “Pop” Pressure Vehicle Test Procedure

Note: Bendix is not aware of any federal legislation that specifi es the pressure at which the YELLOW 
parking brake control valve must automatically “trip” to apply the vehicle parking brakes.  This includes the 
Federal Motor Carrier Safety Regulations (FMCSR) for in-use vehicles, the CVSA out-of-service criteria, 
and the Federal Motor Vehicle Safety Standards (FMVSS) for newly manufactured vehicles.  Although 
the “trip” pressure for the parking brake control valve is not stipulated for in-use or newly manufactured 
vehicles, a parking brake control valve “trip” pressure of 20-40 psi is currently (02/2009) specifi ed as part of 
the Commercial Driver License in the CDL Manual.  The CDL Manual is not consistent with the regulations 
cited above.  See Bendix Bulletin TCH-003-051.                                                          

           

continued . . .

TEST 4

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1. Make  and  hold  an  80-90  psi  brake  application.  This  can  be  accomplished  by 

using the Bendix

®

 BVA-85

™

 brake valve actuator.  If the vehicle is not equipped 

with a BVA-85 brake valve actuator, an assistant should be used to maintain a 
constant application during these tests.

2. Allow pressure to stabilize for 1 minute; then begin timing for 2 minutes while 

watching the dash gauges for a pressure drop.

A. Pressure Drop: 

Single Vehicle (A 4 psi drop within 2 minutes is allowable for 

either service reservoir)

B.  Pressure Drop: 

Tractor/Trailer (A 6 psi drop within 2 minutes is allowable for 

either service reservoir)

C. Pressure Drop: 

Tractor/2 Trailers (An 8 psi drop within 2 minutes is allowable 

for either service reservoir)

3.

Check brake chamber push rod travel (refer to chart below for the CVSA Max 
allowable Stroke).  With the parking brakes released and service brakes applied 
with 80 to 90 psi of air pressure to the service chambers.

4. Check  the  angle  formed  between  the  brake  chamber  push  rod  and  the  slack 

adjuster arm. It should be equal to or slightly less than 90° in the applied position 
(80-90 psi) and the same across the axle.

CHECKLIST 4

NOTE: A leak detector or soap solution will aid in locating the faulty component.

1.  Loose service lines and fi ttings

2.  Stoplight switch

3.  Trailer control valve

4.  Dual brake valve

5.  Tractor protection valve

6.  Double check valve

7.  Service brake relay valves

8.  Spring  brake  chamber,  service  chamber 

and/or brake chamber diaphragms

9.  Inverting relay spring brake control valve (where applicable – usually found on the spring 

brake relay valve) straight trucks and buses

repair or replace to obtain desired setting.

CAUTION:  If the brake chamber push rod travel exceeds   the  allowable  stroke,  identify  and  correct  the 
root cause of the excess stroke.  Do not make manual adjustments of an automatic slack adjuster once 
it can no longer automatically adjust the brakes.  Manual adjustment DOES NOT fi x the underlying wheel 
end adjustment.  As soon as possible, have the vehicle inspected by a qualifi ed technician or consult the 
manufacturer’s troubleshooting guidelines to fi nd and fi x the problem.

TEST 1

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1. Drain all the reservoirs to 0 psi.

2. Start  the  engine  and  run  at  fast  idle.    The  low  pressure  warning  should  be 

on.  Note: on vehicles equipped with ABS, the warning lamp will also come on 
momentarily  when  the  ignition  is  turned  on.    On  some  systems,  such  as  the 
Bendix

®

 AD-IS

®

 dryer system (illustrated), reservoirs may not fi ll simultaneously 

and one reservoir may fi ll to 110 psi before the other starts to fi ll.  

3. Low pressure warning; dash warning lamp should go off above 60 psi.

4. Build up time; pressure should build from 85-100 psi within 40 seconds.

5. Governor cut-out; cuts out at the correct pressure, usually 125-135 psi.

6. Governor  cut-in;  reduce  the  service  air  pressure  to  governor  cut-in.  The 

difference between cut-in and cut-out pressure must not exceed 30 psi.

CHECKLIST 1

1.  Check the warning lamp wiring.
2.  Check the warning lamp bulb.
3.  Repair or replace the buzzer, bulb or low pressure warning switch(es).

1.  Check the dash gauge with test gauge known to be accurate. 
2.  Repair,  replace,  or  adjust  the  governor  as  necessary  after  ensuring  the  compressor  unloader 

mechanism is operating correctly.

1.  Check the dash gauge with test gauge known to be accurate.
2.  Repair or replace the faulty low pressure indicator switch.

1.  Examine  the  compressor  air  inlet  fi lter  and  inlet  line  checking  for  restrictions,  damage  or  wear.  

Clean or replace the fi lter or inlet line as necessary.

2.  Check the  compressor discharge port and line for excessive carbon. Clean or replace the discharge 

line as necessary.  If there is carbon, fi nd the cause of the excessive heat.

3.  With the system fully charged and governor in the unloaded mode, listen at the compressor inlet for 

leakage. If leakage can be heard, remove the unloaders and repair or replace as necessary.

TEST 2 

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1. Allow the air pressure to stabilize for at least 1 minute.

2. Observe the dash gauge pressures for 2 minutes and note any pressure drop.

A. Pressure Drop: Single Vehicle (A 4 psi drop within 2 minutes is allowable for 

either service reservoir)

B.  Pressure Drop: Tractor/Trailer (A 6 psi drop within 2 minutes is allowable for 

either service reservoir)

C. Pressure Drop: Tractor/2 Trailers (An 8 psi drop within 2 minutes is allowable 

for either service reservoir)

Standard

1

 

Premium

2

Standard

1

 

Premium

2

þ

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3. 

“Pop” Pressure Vehicle Test Procedure (Continued)

A. Install an accurate “shop standard” pressure gauge in the secondary service 

reservoir.

B.  Build  pressure  in  the  service  reservoirs  until  the  compressor  cut-out  is 

reached, shut the engine off.

C. Fully open the manual drain valve on the primary service reservoir allowing 

the reservoir to drain completely.

D. Open the secondary reservoir’s manual drain valve creating a bleed rate of 

approximately 20-50 psi/min.

E. Monitor the pressure gauge noting the pressure at which the parking control 

automatically “pops”.  This is not a Federal requirement - See Note in previous 
column.

4.   For Towing Vehicles Only - Test the tractor protection valve feature

 

A. Charge the air system to governor cut-out.

B. Disconnect the service or control (blue) line to the trailer.

C. Take care to restrain the service coupling and direct fl ow safely away while 

making and holding a full service brake application via the foot valve.

D. As the service application is vented through the open gladhand, the service 

system  pressure  drops  until  the  tractor  protection  control  (red)  valve  trips 
and shuts off the leak through the open coupling.  This leak must be shut off.

E. Record the pressure in the service reservoirs. Disconnect the trailer supply 

coupling  to  verify  that  the  supply  or  emergency  (red)  coupling  has  been 
vented to atmosphere, thereby activating the trailer emergency feature.

5.  Close  the  drain  cocks,  recharge  the  system  and  drain  the  rear  axle  primary 

reservoir to 0 psi.

A. The front axle reservoir should retain most of its pressure.

B. On combination vehicles, the trailer air system should remain charged.

6. With  no  air  pressure  in  the  rear  axle  reservoir,  make  and  release  a  brake 

application. 

A. Front axle brakes should apply and release.

B. On combination vehicles, the trailer brakes should also apply and release. 

C. If the vehicle is equipped with a spring brake modulating valve, typically found 

on trucks, towing trucks and buses, the rear axle brakes should also apply 
and release by exhausting spring brake air.

CHECKLIST 6

TEST 6 

BW1231  ©  2013 Bendix Commercial Vehicle Systems LLC, a member of the Knorr-Bremse Group • All Rights Reserved • 02/2013• Printed in U.S.A.

BW2780  Troubleshooting Bendix

®

 ESP

®

 Stability System

BW1555  Brake Balance Procedure
BW1114  Quick Reference Catalog
BW5057  Air Brake Handbook
SD-13-4863  Service Data Sheet for Bendix

® 

EC-60

™

 ABS/ATC 

Standard & Premium Controllers

12

1-3/8”

12L

1-3/4”

16

1-3/4”

16L

2”

20

1-3/4”

20L

2”

20L3

2-1/2”

24

1-3/4”

24L

2”

24L3

2-1/2”

30

2”

30L

2-1/2”

36

2-1/4”

1.  Fittings

2.  Kinked hose or tubing

3.  Pressure protection valves

4.  Double check valves

5.  Tractor protection valve

6.  Tractor protection control valve

7.  Parking control valve

8.  Relay valves (antilock modulators)

9.  Trailer spring brake control valve

10. Inverting relay spring brake control valve (optional) 

straight trucks and buses