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