Bendix Commercial Vehicle Systems EC-14 ANTILOCK CONTROLLER 5/04 - Manual (Page 5)

5
FIGURE 5 - M-21 ™ & M-22 ™ MODULATORS
The EC-14 ™ controller is designed to be mounted directly
on a modulator relay valve assembly like the M-12 ™
modulator. The two separate components (EC-14 ™ controller
and M-12 ™ modulator) become a single assembly. The
M-12 ™ modulator is a combination valve consisting of a
standard relay valve and solenoid assembly. The M-12 ™
modulator replaces the standard relay valve used to speed
up the application and release of the vehicle’s rear axle
brakes. An internal, four pin, wiring harness connects the
EC-14
™ controller to the M-12 ™ modulator solenoid assembly.
For additional information and service procedures see Bendix
Service Data Sheet SD-13-4772.
In addition to the M-12 ™ modulator, the EC-14 ™ controller
also controls a single, external modulator like the M-21 ™ or
M-22 ™ . Connected to the EC-14 ™ controller via a wire
harness, the M-21 ™ or M-22 ™ modulator is essentially a
high capacity, on/off air valve that incorporates a pair of
electrical solenoids for control. The solenoids provide the
electric-air link between the antilock controller electronics
and the air brake system. Unlike the M-12
™ , the M-21 ™ or
M-22 ™ modulator is not combined with a service relay valve.
For additional information and service procedures see Bendix
Service Data Sheet SD-13-4793.
A Dash Light and its electrical relay is connected to, and
controlled by, the EC-14
™ 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-14
™ controller which allows the EC-14 ™
controller to temporarily “disable” the retarder during certain
modes of operation. While the EC-14
™ 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-14 ™ controller to
“report” its operating condition to a specialized, external
computer in response to certain commands it receives. The
EC-14
™ controller data link configuration conforms to S.A.E.
standard J1708 and the protocol, or coded language used,
conforms to S.A.E. standard J1537. There are two
connections to the EC-14
™ controller devoted to the data
link. While the EC-14 ™ 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-14
™ controller to be
functional.
OPERATION
OPERATIONAL PHILOSOPHY
The Bendix ® EC-14 ™ controller provides axle braking control
by using four speed sensors and two modulators. By
monitoring the rate of deceleration during braking, and
subsequently adjusting the brake application pressure to
each axle, the EC-14
™ controller is able to provide improved
braking while maintaining vehicle stability.
3 PIN WIRE
HARNESS
CONNECTOR
MOUNTING
HOLE
EXHAUST
SUPPLY
PORT
MOUNTING
HOLE
3 PIN WIRE
HARNESS
CONNECTOR
DELIVERY
PORT
EXHAUST
SUPPLY
PORT
M-22 ™ MODULATOR M-21 ™ MODULATOR