Abs/Atc System; Abs Component Function - Monaco DIPLOMAT 2004 Owner's Manual

DIPLOMAT 2004

ABS/ATC SYSTEM

(Anti-lock
Brakes)
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The motorhome is equipped with an anti-lock braking system (ABS) and
automatic traction control system (ATC). The ABS system monitors wheel
rotation speeds by using a 100-tooth magnetic tone ring mounted to the hub.
Revolving with the wheel, the magnetic tone ring is polarized giving positive and
negative pulsations. A stationary sensor is mounted adjacent to the tone ring
monitoring the magnetic pulses. The pulses are monitored by the ABS
electronic control unit (ECU).
The ECU monitors all available wheel sensors at the rate of 100 times per
second. The ECU controls Pressure Modulator Valves. Pressure Modulator Valves
have two electric over air solenoids, a hold solenoid and a release solenoid. The mod-
ulator valves are open under normal braking, allowing a straight through air sig-
nal from the treadle valve to the brake chamber. Should a wheel lose traction
under a braking application, the ECU will energize the hold solenoid of the Pressure
Modulator Valve to interrupt the air signal from the treadle valve to the brake
chamber. The release solenoid vents the existing air signal, at the brake chamber
to the atmosphere, allowing the skidding tire to regain
traction. Skidding tires have less tractive efficiency. It is possible, under certain
conditions, to have the wheel(s) skid with a normal functioning ABS system.
The ABS itself does not apply additional braking power. The purpose of the
ABS is limiting brake torque to prevent wheel locking that results in the loss of
lateral stability, and increased stopping distances. Cautious driving practices and
maintaining adequate safe distances when following vehicles is the key to safe
vehicle operation.
WARNING: The ABS/ATC system is designed to increase tire to road
surface traction. The system cannot overcome naturally occurring laws
of physics. The ABS/ATC system combined with safe driving
practices reduce the possibility of wheel skid and loss of lateral
stability.

ABS Component Function:

• Speed sensors and tone rings on each wheel monitor wheel
rotation.
• Each speed sensor communicates wheel rotation pulses to the
Electronic Control Unit.
• ECU receives the speed sensor inputs, interprets the signal
pulses, calculates speed and acceleration rates of each wheel.
• Based on the speed sensor input, the ECU detects
impending wheel lock and operates the ABS Modulator
Valves required for proper control. The Modulator Valves can
be operated in the air, release or hold modes to regulate air
pressure to the brake chambers.
• The braking force is applied at a level which minimizes the
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stopping distances while maintaining as much lateral
stability as possible.
CHASSIS INFORMATION