Technical Information – ABS (Anti – Lock Brake System)

 

Reservoir

 

When the passage opens between the caliper and the reservoir with the outlet solenoid valve in “Decrease Mode”, the brake fluid flows into the reservoir by pushing the piston, stays there temporar-ily, and then returns to the master cylinder. With the outlet solenoid valve “Increase or Hold Mode”, the pump returns the remaining brake fluid in the reservoir to the master cylinder.

 

 

1. From Outlet Solenoid Valve

 

2. To Pump

 

Pump Motor

 

The pump motor operates the pump, supply or return the brake fluid from the pump.

 

Pump

 

The pump operates continuously when the ABS is activated. The pump is driven by the motor and supply the brake fluid to the caliper or return the brake fluid in the reservoir to the master cylinder. The piston is reciprocated by the eccentric cam [A] on the end of the motor shaft and the pump sucks in or discharge the brake fluid.

 

When the pump pulls fluid in, the piston [B] is moved right by the force of the spring [C]. At this time, the spring [D] is compressed by the pressure of the brake fluid in the reservoir to open the inlet valve [E] and the brake fluid flows into the cylinder [F]. The outlet valve [G] is held closed by the force of the spring [H].

 

 

When the pump discharges the brake fluid, the inlet valve [E] is closed by the spring [D], and the piston [B] is moved left by the cam [A], producing pressure in the cylinder [F]. The pressure pushes the spring [H], opens the outlet valve [G], and the brake fluid returns to the master cylinder.

 

Spring [C]

 

GENERAL INFORMATION 1-21

 

Technical Information – ABS (Anti – Lock Brake System)

 

ABS Solenoid Valve Relay

 

ABS solenoid valve relay supply or intercept the power to the inlet or outlet solenoid valves.

 

ABS Motor Relay

 

ABS motor relay supply or intercept the power to the pump motor.

 

ECU

 

ECU inputs the sensor signal.

 

ECU calculates the wheel condition for the slip.

 

ECU controls the hydraulic unit.

 

ECU sends the actuating signals to the ABS indicator light (LED).

 

GENERAL INFORMATION

 

Technical Information – ABS (Anti – Lock Brake System)

 

ABS Operation

 

The ABS has two independent hydraulic lines, one for the front wheel and the other for the rear wheel. The front wheel system is explained here and is identical to the rear wheel system.

 

ABS in Action

 

(Increase Mode)

 

When the caliper fluid pressure is to be increased, first the tappet of inlet solenoid valve opens (normally open). The brake fluid flows through the valve body as shown in the diagram below to increase the brake fluid pressure in the caliper. The master cylinder pressurizes to the brake caliper directly, increasing the braking force.

 

 

1. Brake Lever

 

2. Front Inlet Solenoid Valve

 

3. Pump Motor

 

4. Pump

 

5. Front Reservoir

 

6. Front Outlet Solenoid Valve

 

7. Front Caliper

 

GENERAL INFORMATION 1-23

 

Technical Information – ABS (Anti – Lock Brake System)

 

(Hold Mode)

 

When the caliper fluid pressure is to be hold, the tappet of inlet solenoid valve closes, and the passage (master cylinder side) to the valve body is intercepted. No matter how hard the brake lever is pulled, the brake fluid pressure in the caliper is maintained at a given level.

 

 

1. Brake Lever

 

2. Front Inlet Solenoid Valve

 

3. Pump Motor

 

4. Pump

 

5. Front Reservoir

 

6. Front Outlet Solenoid Valve

 

7. Front Caliper

 

GENERAL INFORMATION

 

Technical Information – ABS (Anti – Lock Brake System)

 

(Decrease Mode)

 

When the caliper fluid pressure is to be decreased, the tappet of inlet solenoid valve closes, and the passage to the valve body is intercepted. The valve of outlet solenoid valve is opened by the operation of the armature, and the brake fluid flows to the reservoir. ECU operates pump, and the pump returns the brake fluid in the reservoir to the master cylinder. The brake fluid pressure is decreased, and the wheel is prevented from locking.

 

 

1. Brake Lever

 

2. Front Inlet Solenoid Valve

 

3. Pump Motor

 

4. Pump

 

5. Front Reservoir

 

6. Front Outlet Solenoid Valve

 

7. Front Caliper

 

GENERAL INFORMATION 1-25

 

Technical Information – ABS (Anti – Lock Brake System)