Operation When sctuating the brake pedal, hydroulic pressure in the broke system increases Due to the pre pistons in the wheel cylinder move outward. The pistons press the brake shoes against the brake drum. Kinetic energy of the vehicle is conve causes the drum and wheel to slow down together. When you release the brake pedal, the pressure in the brake system decreases. The return spring shoes away from the brake drum and the brake pistons are pushed back into the brake cylinder. The hold down springs secure the brake shoes to the backing plate. What happens when you release the brake pedal? The rotational direction of the brake drum changes. The brake drum and wheel are slowed down together. The return spring pulls the brake shoes away from the brake drum.