Bendix Commercial Vehicle Systems M32QR ANTILOCK MODULATOR ASSY - Manual

1
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
Previous
Model
M-30
™
Modulator
FIGURE 2: M-30 ™ MODULATOR
* All M-32QR ™ modulators
except p/n 5011281 (Bluebird)
have the shorter exhaust port.