BENDIX M-21-M-22 ANTILOCK MOD ASSY Manual de servicio descargar pdf (Pagina 21)

An antilock dashlight and its electrical relay are connected to, and controlled by, the

EC-16, and serve as a means of advising the driver of the condition of the antilock

system.

A connection to the engine or transmission retarder and its relay is provided on the

EC-16, which allows the EC-16 to temporarily disable the retarder during certain

modes of operation. While the EC-1 is capable of this function and the 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.

OPERATION

Antilock Philosophy

The Bendix EC-16 antilock system uses individual sensors, modulators and an electronic

controller to control the four vehicle wheel ends. By monitoring the deceleration rate

during braking and subsequently adjusting the brake application pressure at each

wheel, the EC-16 is able to improve braking between the vehicle tire and the road

surface it is on while maintaining vehicle stability.

The rear axle brakes are controlled independently; therefore brake application pressure

at an individual wheel is adjusted solely on the basis of its behavior on the road sur-

face on which it is traveling.

While each steering axle brake is under the control of an individual modulator, the

EC-16 does not treat these brakes totally independently. The EC-16 uses a modified

individual control philosophy for 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

(for example, ice close to the curb and a dry crown). Essentially, the EC-16 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 braking during the entire stop.

In the case of vehicles equipped with tandem rear axles (6 x 2, 6 x 4), the wheel speed

sensors are installed at the wheels on the axle that is most likely to lock first. A single

modulator controls both curbside brakes on the tandem, and another modulator con-

trols both brakes on the driver’s side of the tandem. With this arrangement of speed

sensors and modulators, both brakes on one side of the tandem are treated as one,

since they will most likely be on the same type of road surface.

Non-antilock Brake Application

During normal braking, air pressure from the brake valve enters the control port of the

service relay valve. The service relay delivers air to, and through, the antilock modulator

located near the braked wheel, and into the brake actuator. The service brakes are thus

applied. If the wheel sensors do not detect an impending wheel lock up, the EC-16

does not initiate any corrective action, and the vehicle comes to a stop in a normal

fashion.

Air Brake System

Revised 11/15/99

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BENDIX M-21-M-22 ANTILOCK MOD ASSY Manual de servicio Pagina 21