Antilock Brakes / Traction Control Systems: Description and Operation
GENERAL DESCRIPTIONTop components such as Brembo TM brakes, EBD and sports ABS improve braking power and braking stability.
SPORTS ABS
^ 4-wheel independent control optimizes the brake force to each wheel to achieve a balance of improved braking force and braking stability.
^ A steering angular velocity sensor was added to monitor the steering angle status. Braking force is altered in response to the steering status to improve the quality of steering when cornering.
^ The steering angular velocity sensor, lateral G-sensor and longitudinal G-sensor accurately monitor driving conditions and optimize ABS control to match the specific driving conditions.
EBD (ELECTRONIC BRAKE-FORCE DISTRIBUTION SYSTEM)
^ Rear brake power is electronically controlled to optimize performance in accordance with road and load conditions and to ensure optimal distribution of braking force between the front and rear brakes.
^ Rear brake fluid pressure control employs a brake modulator hydraulic unit solenoid valve that made it possible to eliminate the pressure control valves (proportioning valves).
^ Effective use of rear wheel brake force reduces temperature build-up in the front brakes under hard braking conditions.
^ Independent control of the left and right rear brakes when braking during cornering achieves a balance of improved vehicle stability and braking force.
CONSTRUCTION DIAGRAM
SYSTEM CHECK SOUND
When starting the engine, a thudding sound can sometimes be heard coming from the engine compartment. This is a normal sound during the ABS self-check.
ABS OPERATION SOUNDS AND SENSATIONS
During normal operation, the ABS makes several sounds that may seem unusual at first:
^ A whining sound is caused by the ABS hydraulic unit motor.
^ When pressure is applied to the brake pedal, the pulsation of the pedal causes a scraping sound.
^ When the brakes are applied firmly, the ABS operates, rapidly applying and releasing the brakes many times per second. This repeated application and release of braking forces can cause the suspension to make a thumping sound and the tires to squeak.
LONG STOPPING DISTANCES ON LOOSE ROAD SURFACES
When braking on loose surfaces like snow-covered or gravel roads, the stopping distance can be longer for an ABS-equipped vehicle than the stopping distance for a vehicle with a conventional brake system.
SHOCK AT STARTING CHECK
Shock may be felt when the brake pedal is lightly pressed while driving at a low speed. This is a normal characteristic because the ABS system operation check is carried out when vehicle speed is 8 km/h (5 mph) or less.