Mazda Training manual — part 104

Dynamic Driving Safety Systems

EBA

Overview

•

The basic construction of the brake booster with EBA is similar to a conventional type,
except that the following parts have been added:

–

Balls

–

Ball cage

–

Ball sleeve

–

Lock sleeve

–

Spring

–

Centre spring

L2003_02043

1

Ball sleeve

6

Centre spring

2 Spring

7 Ball

3

Valve piston

8

Lock sleeve

4

Disc valve

9

Ball cage

5

Control housing

10

Rubber element

Curriculum Training

02-75

EBA

Dynamic Driving Safety Systems

Operation

•

During normal braking situations, the brake booster with EBA operates in the same way
as a conventional one. This means that the driver can always modulate the brake force
applied to the wheels.

•

If the activation threshold, defined by a pre-set characteristic curve, is exceeded during
braking, the EBA operates. The determination of the activation threshold is based on
pedal movement parameters. It is a result of how fast and how hard the brake pedal is
pressed.

•

The mechanical EBA uses the fact that, in a brake booster the valve piston moves ahead
of the control housing when brake operation starts. Thus, there is a relative travel
distance between the control housing and the valve piston. The value of this varies
depending on the force applied to the brake pedal and on the pedal speed.

•

The relative travel distance is small when the pedal moves slowly with low force applied
to it, and it is larger when the pedal moves faster with higher force applied to it.

02-76 Curriculum

Training

Dynamic Driving Safety Systems

EBA

Normal Braking

•

During normal braking, the movement of the pedal causes only a small relative travel
distance, and the EBA does not operate. The lock sleeve is held in its rest position by
the force applied by the spring, and the ball sleeve remains free to move axially.

L2003_02045

1

Ball sleeve

3

Speed of movement

2

Relative travel distance

4

Lock sleeve

Curriculum Training

02-77

EBA

Dynamic Driving Safety Systems

Emergency Braking

•

If the activation threshold is exceeded because of an emergency braking situation, i.e.
the driver presses the brake pedal very fast causing a large relative travel distance, the
balls move on the ball sleeve toward the valve piston, allowing the spring-loaded lock
sleeve to move completely to its end position. Now, the balls are locked, and the ball
sleeve can no longer be moved in the closing direction of the disc valve. Thus, the valve
piston cannot close the disc valve.

•

Consequently the EBA is active, the brake pressure is increased up to the wheel locking
limit, and the brake pedal can be moved to its maximum pressure point without any
effort. The brake pressure remains at the ABS control limit until the brake pedal is
completely released again.

L2003_02046

1

Ball sleeve

5

Valve piston

2 Spring

6 Ball

3

Relative travel distance

7

Locking movement

4

Disc valve

8

Speed of movement

02-78 Curriculum

Training