Drum Brake Has Stronger Braking Force. Why Do You Still Pursue Disc Brake?
Disc brake, which is the most widely used brake system in passenger cars, is mainly composed of brake disc, vacuum booster pump, brake pad, brake sub pump, brake oil circuit and other hydraulic brake control systems. When we press the brake pedal, the brake oil flows to each brake sub pump through the brake master cylinder and vacuum booster pump, then pushes the brake pliers to clamp the brake disc, thus creating friction and finally achieving the braking effect.
The brake force of disc brake depends on the pressure that brake oil can reach when it passes through vacuum booster pump and brake sub pump. The brake pump used in our common passenger cars is of single piston hydraulic structure. It can provide braking force relatively small. Therefore, it needs vacuum booster pump to provide greater hydraulic thrust. However, although the vacuum booster pump can provide better braking force, the brake hydraulic limit value of disc brake will not exceed 10 MPa generally.
What is a 10 MPa pressure concept?
0.1 MPa is a standard atmospheric pressure, which is the pressure provided by a 10 meter water column with a bottom area of 1cm2. The weight of a water column of 0.1 MPa is exactly 1kg, so 10 MPa is the pressure provided by a 100 kg water column. In the process of deceleration, the car will produce acceleration in the opposite direction of motion under the action of resistance, while the value of passenger car in the process of deceleration is about 0-1g. 1g refers to the emergency braking state, and its pressure on hydraulic braking is 10 MPa.
According to the bearing pressure of single brake pad = brake hydraulic line pressure △ 2, the maximum pressure of single brake pad of disc brake system is 5 MPa. Let's assume that the friction area of the brake pad in one revolution of the brake disc is 5cm * 60cm = 300cm2. According to the formula of 1MPa = 10kg / cm2, we can calculate that the limit pressure of a single brake pad is equal to 50kg / cm2x300cm2 = 15000kg = 15t.
Of course, this value is basically the limit value of family passenger cars. For some sports cars, performance cars or luxury cars, this value may be higher.
