Advanced Braking

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When a wheel spins under acceleration the ABS/TRC ECU decides if brake intervention is required. If it is, the pump in the ABS actuator will run to supply pressurised fluid to the brake of the spinning wheel via the inlet solenoid valve (remember the driver is not applying the brake so brake pressure has to be generated by other means). fluid being pumped back to the brake master cylinder at this time, solenoid valve A is closed (see diagram). Solenoid B is opened to supply hydraulic fluid to the pump as necessary. The braked wheel should now slow down and more power will be supplied to the opposite wheel (via the differential) as long as power is still applied by the driver/ECU. As the wheel slows, the outlet valve allows fluid to be bled back to the reservoir/pump. The cycle is repeated until either power is reduced enough to prevent spin or the wheels start to turn at very similar speeds (equal grip).

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S374_322

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