ABS 22 ANTI-LOCK BRAKES been eliminated from the rear brake circuit. EBD results in ideal pressure distribution for the rear axle wheels. With EBD, the rear axle wheels either lock along with front axle wheels during partial braking OR the rear axle wheels may lock after the front axle wheels. EBD never allows the rear axle wheels to lock before the front axle wheels. Principle 1. The principle is precise control of the rear axle brake pressure such that it follows the ideal brake pressure distribution curve closely. This is achieved by the inclusion of a special control logic to the ABS ECU (instead of LCRV). 2. Rear brake pressure is controlled so that rear slip ratio will always be less than or same as that of front.The brake slip of each wheel during braking is calculated by means of the wheel speed signal of the respective wheel. 3. Therefore rear wheel locking does not precede that of front wheel. 4. Consequently brake force at the rear axle can be made to follow the ideal pressure distribution curve more closely (Figure 14). This enhances the contribution of the rear axle wheels for braking & thereby improves braking efficiency. 5. With this precise brake force control of each rear wheel as per its individual requirement, at the particular point of time, can be achieved. EBD Working 1. Just before rear wheel tends to lock preceding to front wheel, the EBD function of ABS ECU actuates the inlet solenoid valve & closes it, so that the brake oil pressure from TMC is blocked at HU only instead of reaching that particular wheel cylinder & hence the locking is prevented. Some times, EBD also actuates outlet solenoid valve & opens it for very short intervals of time, so that locking of the rear wheels is avoided. 2. Soon after the rear wheels recover from locking phase, the inlet & outlet solenoid valves are switched OFF, so that the brake pressure applied at MC be transmitted to the rear wheel cylinder/ caliper. 3. Motor pump does not act at this time.
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