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If the driver has to press the brake pedal several times to make the vehicle brake, it is concluded that:
When the driver needs to repeatedly press the brake pedal to brake the vehicle, this generally indicates the presence of air in the hydraulic braking circuit. Since air is compressible, unlike brake fluid, the initial pressure is absorbed by the air bubbles, making it necessary to press the pedal several times to build up enough pressure to activate the brakes. Excessive tension in the brake shoe return springs or a warped drum do not cause this specific behavior of needing to pump the pedal to achieve braking. A warped drum would cause vibrations or shuddering when braking, while problems with the springs would affect the return of the brake shoes, but not the loss of initial pressure that requires pumping the pedal.