[Answer] What is the purpose of the master cylinder residual check valve(s) on vehicles equipped with drum brakes? A. allows the driver to pump up the brakes B. prevents air from entering the hydraulic systemC. prevents wheel lockup by reducing the hydraulic pressureD. reduces pedal pulsation by controlling hydraulic pressure

Answer: B. Residual check valve(s) are used on drum brakes to keep residual low pressure (slight static pressure) in the brake system at all times even when the brake pedal Is released. This pressure (5-20 psi) keeps the lips of the wheel cylinder piston cups tight against the cylinder walls to prevent air from entering the system when at rest (brakes released).
What is the purpose of the master cylinder residual check valve(s) on vehicles equipped with drum brakes? A. allows the driver to pump up the brakes B. prevents …

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