How much do you know about drum brakes

A typical drum brake is mainly composed of components such as a bottom plate, a brake drum, brake shoes, a wheel cylinder (brake cylinder), a return spring and a positioning pin. The bottom plate is installed at a fixed position of the axle , and it is fixed. It is equipped with brake shoes, wheel cylinders, return springs and positioning pins to withstand the rotational torque during braking. Each drum has a pair of brake shoes with friction linings.

The brake drum is mounted on the hub and is a part that rotates with the wheel. It is made of cast iron and looks like a drum. When the vehicle brakes, the wheel cylinder piston pushes the brake shoe to press the brake drum, and the brake drum is decelerated by friction, forcing the wheel to stop rotating. The structure of the rear wheel drum brake is shown in the figure below. It is a wheel cylinder unbalanced brake. In the brake, the rotating part is a brake drum, and the brake drum is bolted to the wheel and rotates with the wheel; The fixing part is a brake floor, which is mounted on a flange at the end of the rear bridge, and the brake floor is provided with brake parts such as brake shoes and wheel brake cylinder assembly and the like. In the brake drum, the lower ends of the brake shoes and the brake linings on both sides are inserted into the corresponding grooves of the brake floor, and the upper ends abut on the piston of the wheel brake cylinder adjacent to the upper suppo rt point. There is also a support point for the handbrake putter, which is stuck in the putter. The upper part of the brake shoe is tightened by the springs and the lower part is tightened by the spring

The brake shoe is pressed against the brake bottom plate by a limit screw, a limit spring seat and a limit spring. When braking, press the brake pedal, and the brake fluid pressure enters the wheel brake cylinder to move the piston outward, pushing the brake shoe and the brake friction plate against the brake drum. Slow down the wheels until they stop turning. When braking by hand, pull the hand brake handle, pull the hand brake cable forward by the hand brake cable, push the left and right brake shoes away and press the brake drum by the lever 2's lever action; When the hand brake handle is stuck, the brake shoe is pressed against the brake drum, which becomes the parking brake of the car. The gap between the brake shoe and the brake drum is automatically adjusted by the adjusting wedge mounted on the push rod. The lower end of the adjusting wedge is provided with an adjusting spring, and the adjusting spring pulls the adjusting wedge to automatically adjust the clearance.