6
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 the antilock exhaust or reapply mode from the
antilock hold mode.
ANTILOCK REAPPLY
If the antilock controller senses that wheel speed has
increased sufficiently enough to require re-application of
braking pressure, it deenergizes the supply and exhaust
solenoids. With both solenoids de-energized, the modulator
re-applies air to the brakes in the same manner it did during
a non-antilock event.
VEHICLE PREPARATION
WARNING! PLEASE READ AND FOLLOW
THESE INSTRUCTIONS TO
AVOID
PERSONAL INJURY OR DEATH:
When working on or around a vehicle, the following
general precautions should be observed at all times.
1.
Park the vehicle on a level surface, apply the
parking brakes, and always block the wheels.
Always wear safety glasses.
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. Where circumstances require that the
engine be in operation, EXTREME CAUTION should
be used to prevent personal injury resulting from
contact with moving, rotating, leaking, heated or
electrically charged components.
3.
Do not attempt to install, remove, disassemble or
assemble a component until you have read and
thoroughly understand the recommended
procedures. Use only the proper tools and observe
all precautions pertaining to use of those tools.
4.
If the work is being performed on the vehicle’s air
brake system, or any auxiliary pressurized air
systems, make certain to drain the air pressure from
all reservoirs before beginning ANY work on the
vehicle. If the vehicle is equipped with an AD-IS
®
air dryer system or a dryer reservoir module, be
sure to drain the purge reservoir.
5.
Following the vehicle manufacturer’s
recommended procedures, deactivate the electrical
system in a manner that safely removes all
electrical power from the vehicle.
6.
Never exceed manufacturer’s recommended
pressures.
7.
Never connect or disconnect a hose or line
containing pressure; it may whip. Never remove a
component or plug unless you are certain all
system pressure has been depleted.
FIGURE 10: M-30
™
ANTILOCK APPLICATION HELD POSITION
BRAKE VALVE
BIAS VALVE
SUPPLY OR
HOLD
DIAPHRAGM
HOLD
VALVE
SPRING
EXHAUST
DIAPHRAGM
EXHAUST
PORT
BRAKE
CHAMBER
EXHAUST VALVE
