BENDIX M32 M32QR ANTILOCK MODULATOR ASSY Manual page 5

Brake
Supply
Valve
Port
Supply or Hold
Diaphragm
Closed
Spring
Solenoid
Energized:
Moves to Exhaust
Down
Port
Position
FIGURE 8: M-32 ™ MODULATOR ANTILOCK EXHAUST OF BRAKES
Brake
Supply
Valve
Port
Supply or Hold
Diaphragm
Closed
Spring
Solenoid
Energized:
Exhaust
Moves to
Port
Down Position
FIGURE 9: M-32 ™ AND M-32QR
place the modulator in the hold position, prior to entering
the reapply mode, when it detects recovery from a locked
wheel condition. In this mode of operation, the modulator
supply/hold solenoid remains energized while the exhaust
solenoid returns to its normal position. The exhaust solenoid
allows application air to flow to the control side of the exhaust
diaphragm, which then seals the exhaust passage. With
the exhaust diaphragm seated, further exhaust of brake
chamber air pressure is prevented. Because the supply
solenoid remains energized, the supply diaphragm remains
seated, thus preventing application air from flowing to the
delivery port and out to the brake chamber. The modulator
can enter both the antilock exhaust or reapply mode from
the antilock hold mode depending on the needs of the
antilock controller.
Delivery
Port
Brake
Chamber
Exhaust
Valve
Open
M-32
Solenoid
Modulator
Energized:
Exhaust Moves to
Diaphragm Down
Position
Delivery
Port
Brake
Chamber
Exhaust
Valve
Closed
M-32
Solenoid
Modulator
Returns
Exhaust
to Up
Diaphragm
Position
™ MODULATORS ANTILOCK APPLICATION HELD POSITION
Brake
Valve
Supply or Hold
Diaphragm
Spring
™
Solenoid
Energized:
Moves to
Down
Position
Brake
Valve
Supply or Hold
Diaphragm
Spring
™
Solenoid
Energized:
Moves to
Down Position
ANTILOCK "REAPPLY" MODE
If the antilock controller senses that wheel speed has
increased sufficiently enough to allow re-application of braking
pressure, without further wheel lock-up, it de-energizes the
supply solenoid. With both solenoids de-energized, the
modulator re-applies air to the brakes in the same manner it
did during a non-antilock event.
Supply
Delivery
Bias
Port
Port
Valve
Solenoid
Energized:
Moves to
Exhaust
Exhaust
Down
Port
Diaphragm
Position
Supply
Delivery
Bias
Port
Port
Valve
Solenoid
Returns
to Up
Exhaust
Exhaust
Position
Port
Diaphragm
Brake
Chamber
Exhaust
Valve
™
M-32QR
Modulator
Brake
Chamber
Exhaust
Valve
M-32QR ™
Modulator
5