BENDIX BW2335 User Manual download pdf

Supply Port

(Casting has

1, SUP)

Exhaust Port

(Casting has

3, EXH)

Supply Port

(Casting has

1, SUP)

Exhaust Port

(Casting has 3, EXH)

Electrical

Connector

Mounting Holes

(.33" Diameter

Through Body)

Electrical

Connector

Delivery Port

(Casting has

2, DEL)

M-32

™

Modulator

M-32QR

™

Modulator*

SD-13-4870

DESCRIPTION

The M-32

™

and M-32QR

™

(quick release) antilock system

modulators (Figure 1) are high capacity, on/off air valves

that incorporate a pair of electrical solenoids for control.

The solenoids provide the electro-pneumatic interface between

the antilock controller electronics and the air brake system.

The modulator is used to control the braking function on

individual or dual service actuators during antilock activity.

The M-32QR

™

modulator is the direct replacement for the

M-30

™

(Figure 2) modulator in all applications. The M-32QR

™

modulator includes a bias valve to provide an internal quick

release function. In applications using an M-32

™

modulator,

an external quick release valve may be required, depending

on the system design (see Figure 3 for typical system

schematics). When used to control both service chambers

on an axle or two chambers on the same side of a tandem

axle, the modulator is sometimes mounted ahead of a quick

release valve, which provides quick exhaust of service

applications during normal braking. In the case of individual

wheel control applications, the modulator is always the last

control valve through which air passes on its way to the

service brake actuator.

Bendix

M-32

™

and M-32QR

™

AntiLock Modulators

FIGURE 1: M-32

™

AND M-32QR

™

MODULATORS

The modulator consists of a die cast aluminum body and a

solenoid assembly which contains one normally open

solenoid, one normally closed solenoid, and an inlet and

exhaust diaphragm valve. A three pin, weather resistant

electrical connector is an integral part of the modulator

solenoid assembly and serves to carry control commands

from the antilock controller to the modulator. Two mounting

holes are provided for frame or cross member mounting of

the valve.

The supply, delivery and exhaust ports on the M-32

™

modulator are identified with a cast, embossed numeral for

positive identification.

Identification Air Line Connection

1, SUP Supply

(incoming air from foot, relay or quick release valve)

2, DEL Delivery

(air delivery to service actuators)

3, EXH Exhaust

Model

M-30

™

Modulator

FIGURE 2: M-30

™

MODULATOR

* All M-32QR

™

modulators

except p/n 5011281 (Bluebird)

have the shorter exhaust port.

1 2 3 4 5 6 7 8

Summary of Contents

Page 1 - AntiLock Modulators

1Supply Port(Casting has1, SUP)Exhaust Port(Casting has3, EXH)Supply Port(Casting has1, SUP)Exhaust Port(Casting has 3, EXH)ElectricalConnector Mounti

Page 2 - Front Axle Systems

2Service &Spring BrakeChamberTo AntilockControllerController/RelayAssemblyM-32™ or M-32QR™ModulatorM-32™ or M-32QR™ModulatorTo AntilockControllerF

Page 3

3FIGURE 4: M-32™ AND M-32QR™ MODULATORS NON-ANTILOCK APPLICATION OF SERVICE BRAKESFIGURE 5: M-32™ AND M-32QR™ MODULATORS NON-ANTILOCK BRAKE APPLICATIO

Page 4 - Modulator

4Rapid Exhaust (Figure 7) - The Rapid Exhaust operationdescribed in the following text occurs when the modulator iscontrolling service chamber(s). Dur

Page 5 - ANTILOCK “REAPPLY” MODE

5FIGURE 8: M-32™ MODULATOR ANTILOCK EXHAUST OF BRAKESSupply or HoldDiaphragmClosedSpringBrakeChamberBrakeValveExhaustDiaphragmExhaustValveOpenExhaustP

Page 6 - PREVENTIVE MAINTENANCE

6PREVENTIVE MAINTENANCEGENERALPerform the tests and inspections presented at theprescribed intervals. If the modulator fails to function asdescribed,

Page 7 - MODULATOR REMOVAL

7Twist-Lock Connector(Bayonet Connector)2. Stop the engine and remove ignition key whenworking under or around the vehicle. Whenworking in the engine

Page 8 - Electrical Control