Drum brakes were open two-horse type, open bodies, Zhang Kaili function of brake shoe and brake shoe support arrangement, different, and makes the brake performance is also different. According to two foot diameter of the brake drum with brake force is balanced, with hydraulic wheel cylinders open drum brakes can be divided into: a simple non-balance, balance and automatic force-three.

Simple non-balanced brake Simple non-balanced brake features: two support points are located in the brake shoe on the bottom, and Zhang Kaili points top of the hoof, shared a round open cylinder and wheel cylinder piston diameter is equal. Brake, two brake shoes in equal under Zhang Kaili, respectively, around the respective support points to deflect outside until the friction plates press the round face of the brake drum. Meanwhile, the brake drum on each of the two brake shoes with normal force. As well as the tangential force and friction. But before and after the effect of the two are not the same.

Front feet: friction the torque about the supporting point of direction about the supporting point of the Zhang Kaili is the same torque direction, so that increases the clamping force of the foot on brake drum, which automatically increases braking distance of the hoof, the brake shoe or collar called potential hoof Hind: Friction the torque about the supporting point the direction of the torque and tension about the supporting point of the opposite direction, so that after the compaction force of the foot on the brake to reduce, thus making the shoe automatically reduce the braking distance of, This shoe is known as reduction potentials hoof or hooves. Although Zhang Kaili on the front and back foot, but due to the role played by the friction is the relationship between positive and negative, and two wheel cylinder piston is floating, with the result that the normal force of the brake drums to two, so called simple non-balanced brake. Rear brake used for light vehicles.

When reversing the car, due to the change in direction of rotation of the brake drum, leading shoe and foot position change, but the effect is the same. Balance brake balance all fastening elements on the brake the brake plate, brake shoe, brake wheel cylinder, the return spring are symmetrical arrangement. Brake, two leading shoe brake, the braking efficiency is greater than a simple non-balanced brake. Reverse brake, two brake shoes from feet, its worse than simple non-balanced brake braking effectiveness. Structure automatically force brake, two-foot putt floating hinged hydraulic opening, promote, make the two potential, but also fully before use Foot-and-hoof after the potential of promoting, bringing the total increase friction torque, this is "automatic".

Source: http://www.civil-test.de/products-1.html