Mazda Training manual — part 87

Dynamic Driving Safety Systems

ABS

During Normal Braking

•

During normal braking, the solenoid valves are not energized. When the brake pedal is
pressed, brake fluid pressure is built up by the master cylinder and passes through the
inlet solenoid valves and then to the brake callipers.

•

The brake fluid pressure is fully controlled by the driver. When the brake pedal is
released, the pressure decreases the opposite way it was built up.

Inlet solenoid valve

Outlet solenoid valve

Pump motor

OFF (open)

OFF (closed)

OFF (stopped)

L2003_T02001

L2003_02005

1 Master

cylinder

6 Reservoir

2

ABS HU/CM

7

Pump motor

3

Outlet solenoid valve

8

Pump

4 Brake

calliper

9 Damper

chamber

5

Inlet solenoid valve

Curriculum Training

02-7

ABS

Dynamic Driving Safety Systems

During ABS Control

•

When wheel lock-up is about to occur, the system starts with the ABS control operation.
ABS can operate three ways:

–

Pressure hold mode

–

Pressure reduction mode

–

Pressure increase mode (which is the same as the “Normal Braking” already
explained on the previous page)

Pressure Hold Mode

•

When the CM detects wheel slip increasing above a specified value, it holds constant
the brake force applied to that wheel to avoid lock-up.

•

Therefore, it energises the corresponding inlet solenoid valve, closing the hydraulic
circuit between the brake calliper and the brake master cylinder. Thus, the brake fluid
pressure inside the related brake calliper cannot increase further.

•

Even if the driver presses the brake pedal further and the brake fluid pressure in the
master cylinder increases, the brake pressure will not increase on a wheel that is
currently in pressure hold mode.

Inlet solenoid valve

Outlet solenoid valve

Pump motor

ON (closed)

OFF (closed)

OFF (stopped)

L2003_T02002

02-8 Curriculum

Training

Dynamic Driving Safety Systems

ABS

L2003_02006

1 Master

cylinder

6 Reservoir

2

ABS HU/CM

7

Pump motor

3

Outlet solenoid valve

8

Pump

4 Brake

calliper

9 Damper

chamber

5

Inlet solenoid valve

Curriculum Training

02-9

ABS

Dynamic Driving Safety Systems

Pressure Reduction Mode

•

When the CM detects that wheel slip is still increasing and reaches a specified value, it
reduces the brake force applied to that wheel.

•

The inlet solenoid valve remains actuated and additionally the appropriate outlet
solenoid valve and the pump motor are energised. Thus the brake fluid pressure in the
brake calliper decreases and the released brake fluid is pumped from the reservoir
towards the brake master cylinder.

Inlet solenoid valve

Outlet solenoid valve

Pump motor

ON (closed)

ON (open)

ON (operating)

L2003_T02003

L2003_02007

1 Master

cylinder

6 Reservoir

2

ABS HU/CM

7

Pump motor

3

Outlet solenoid valve

8

Pump

4 Brake

calliper

9 Damper

chamber

5

Inlet solenoid valve

02-10 Curriculum

Training