Bendix Commercial Vehicle Systems M32QR ANTILOCK MODULATOR ASSY - Manual (Page 5)

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FIGURE 8: M-32 ™ MODULATOR ANTILOCK EXHAUST OF BRAKES
Supply or Hold
Diaphragm
Closed
Spring
Brake
Chamber
Brake
Valve
Exhaust
Diaphragm
Exhaust
Valve
Open
Exhaust
Port
M-32 ™
Modulator
M-32QR ™
Modulator
Bias
Valve
Delivery
Port
Supply
Port
Supply or Hold
Diaphragm
Spring
Brake
Chamber
Brake
Valve
Exhaust
Diaphragm
Exhaust
Valve
Exhaust
Port
Delivery
Port
Supply
Port
FIGURE 9: M-32 ™ AND M-32QR ™ MODULATORS ANTILOCK APPLICATION HELD POSITION
Supply or Hold
Diaphragm
Closed
Spring
Brake
Chamber
Brake
Valve
Exhaust
Valve
Closed
Exhaust
Port
M-32 ™
Modulator
M-32QR ™
Modulator
Bias
Valve
Delivery
Port
Supply
Port
Supply or Hold
Diaphragm
Spring
Brake
Chamber
Brake
Valve
Exhaust
Diaphragm
Exhaust
Valve
Exhaust
Port
Delivery
Port
Supply
Port
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. 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.
Solenoid
Energized:
Moves to
Down
Position
Solenoid
Energized:
Moves to
Down
Position
Solenoid
Energized:
Moves to
Down Position
Solenoid
Energized:
Moves to
Down
Position
Exhaust
Diaphragm
Solenoid
Energized:
Moves to
Down Position
Solenoid
Energized:
Moves to
Down
Position
Solenoid
Returns
to Up
Position
Solenoid
Returns
to Up
Position