User's Manual

ManualsBrandsBENDIX ManualsABS SystemBENDIX BW2335

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.

Summary of content (8 pages)

PAGE 1
SD-13-4870 ® Bendix® M-32™ and M-32QR™ AntiLock Modulators Delivery Port ™ M-32QR Modulator* (Casting has 2, DEL) M-32™ Modulator Supply Port (Casting has 1, SUP) Supply Port (Casting has 1, SUP) Electrical Connector Electrical Connector * All M-32QR™ modulators except p/n 5011281 (Bluebird) have the shorter exhaust port. Previous Model M-30™ Modulator Exhaust Port (Casting has 3, EXH) Mounting Holes (.
PAGE 2
Front Axle Systems Wheel Control Rear Axle System Wheel Control Axle Control Wheel Control Service Brake Chamber To Antilock Controller To Antilock Controller M-32QR ™ Modulator To Antilock Controller M-32 ™ or M-32QR™ Modulator Controller/Relay Assembly or or M-32™ or M-32QR™ Modulator Quick Release Valve ™ M-32QR Modulator M-32™ or M-32QR™ Modulator To Antilock Controller To Antilock Controller Service Brake Chamber To Antilock Controller Service Brake Chamber Quick Release Valve Servi
PAGE 3
Brake Valve Supply Port Delivery Port Brake Valve Supply Port Bias Valve Delivery Port Brake Chamber Supply or Hold Diaphragm Brake Chamber Supply or Hold Diaphragm Spring Spring Exhaust Valve Exhaust Port Exhaust Valve M-32™ Modulator M-32QR™ Modulator Exhaust Diaphragm Exhaust Port Exhaust Diaphragm FIGURE 4: M-32™ AND M-32QR™ MODULATORS NON-ANTILOCK APPLICATION OF SERVICE BRAKES Brake Valve Supply Port Delivery Port Brake Valve Supply Port Bias Valve Delivery Port Brake Chamber
PAGE 4
Brake Valve Supply Port Delivery Port Brake Valve Supply Port Bias Valve Delivery Port Brake Chamber Supply or Hold Diaphragm Open Brake Chamber Supply or Hold Diaphragm Open Spring Exhaust Valve Open Exhaust Port Spring Exhaust Valve Open M-32™ Modulator Exhaust Diaphragm M-32QR™ Modulator Exhaust Port Exhaust Diaphragm FIGURE 7: M-32™ AND M-32QR™ MODULATORS RAPID NON-ANTILOCK EXHAUST OF SERVICE BRAKES Rapid Exhaust (Figure 7) - The Rapid Exhaust operation described in the following text
PAGE 5
Brake Valve Supply Port Delivery Port Brake Valve Supply Port Bias Valve Delivery Port Brake Chamber Supply or Hold Diaphragm Closed Brake Chamber Supply or Hold Diaphragm Spring Spring Exhaust Valve Open Solenoid Energized: Moves to Exhaust Down Port Position Solenoid Energized: Exhaust Moves to Down Diaphragm Position M-32™ Modulator Solenoid Energized: Moves to Down Position Exhaust Valve Exhaust Port Solenoid Energized: Moves to Exhaust Down Diaphragm Position M-32QR™ Modulator FIGUR
PAGE 6
PREVENTIVE MAINTENANCE OPERATION TEST GENERAL To properly test the function of the modulator will require two (2) service technicians. Perform the tests and inspections presented at the prescribed intervals. If the modulator fails to function as described, or leakage is excessive, it should be replaced with a new Bendix unit, available at any authorized parts outlet. EVERY MONTH, 10,000 MILES OR 350 OPERATING HOURS 1.
PAGE 7
41 43 41 42 Source 41 Hold 42 Exhaust 43 42 43 43 41 Threaded (Metric) Connector 42 Twist-Lock Connector (Bayonet Connector) FIGURE 10: M-32™ AND M-32QR™ MODULATORS CONNECTOR VIEWS 2. Stop the engine and remove ignition key when working under or around the vehicle. When working in the engine compartment, the engine should be shut off and the ignition key should be removed.
PAGE 8
Port Designation Supply 1 Delivery 2 Exhaust 3 Electrical Control Source 41 Hold 42 Exhaust 43 FIGURE 11: M-32™ AND M-32QR™ MODULATORS DIN SYMBOL MODULATOR INSTALLATION TECHNICAL INFORMATION 1. Install all air line fittings and plugs, making certain thread sealing material does not enter the valve. Porting 1 Supply Port (from brake, relay or quick release valve) - 1/2" NPT 1 Delivery Port (brake actuator) - 1/2" NPT 1 Push-to-connect for 1/2" tubing 2 NPT supply, PTC delivery 2.