Bendix Commercial Vehicle Systems EC-15 ANTILOCK CONTROLLER ASSY 4/08 - Manual (Page 4)

4
FIGURE 4 - EC-15 ™ CONTROLLER MOUNTED ON AN AR-1 ™ VALVE
EC-15 ™
ELECTRONIC
CONTROLLER
AR-1 ™ ANTILOCK
RELAY VALVE
actuator(s) it controls and is the last air valve through which
air passes on its way to the brake actuator. A wiring harness
connects the modulator to the EC-15
™ antilock controller.
Solenoid valves contained in the modulator provide the
electrical interface between the EC-15
™ controller electronics
and the air brake system. The EC-15 ™ controller is able to
simultaneous and independently control four individual
modulator assemblies.
A dash light and its electrical relay is connected to, and
controlled by, the EC-15
™ controller and serves as a means
of advising the driver of the condition of the antilock system.
A connection to the engine or transmission retarder is
provided on the EC-15
™ controller which allows the EC-15 ™
controller to temporarily “disable” the retarder during certain
modes of operation. While the EC-15
™ controller is capable
of this function, and connections are provided, it is not always
used. Use of the retarder disable function is not essential
but highly recommended for vehicles equipped with a retarder.
The data link function enables the EC-15 ™ controller to “report”
its operating condition to a specialized, external computer
in response to certain commands it receives. The EC-15
™
controller data link configuration conforms to S.A.E. standard
J1708 and the protocol, or coded language used, conforms
to S.A.E. standard J1587. There are two connections to the
EC-15
™ controller devoted to the data link. While the EC-15 ™
controller is capable of this function, and connections are
provided, it is not always used. Use of the data link is not
essential for the EC-15
™ controller to be functional.
OPERATION
GENERAL
The Bendix ® EC-15 ™ antilock controller system provides
individual wheel control by using a wheel speed sensor and
modulator at each wheel. By monitoring the rate of
deceleration during braking, and subsequently adjusting the
brake application pressure at each wheel, the EC-15
™
controller is able to provide improved braking between the
vehicle tire and the road surface it is on, while maintaining
vehicle stability.
The rear axle brakes are controlled completely independent
of each other and therefore brake application pressure at
an individual wheel is adjusted solely on the basis of its
behavior on the road surface on which it is traveling. While
each steering axle brake is under the control of an individual
modulator, the EC-15
™ controller does not treat these brakes
totally independent of each other. The EC-15 ™ controller
utilizes a modified individual control philosophy for the steering
axle brakes. This is done in order to minimize “steering wheel
pull” in the event each wheel is traveling on a different road
surface (e.g.; ice close to the curb and a dry crown).
Essentially the EC-15
™ controller controls the braking force
differences between the two brakes. The wheel on dry
pavement is initially given less braking force and is brought
up to optimum during the stop, while the wheel on ice
attempts to maintain optimum braking during the entire stop.