鳄鱼哥尼流.ppt

Unit 3 Brake System ?1. Description ?(1) Foot brake ?The brake system is one of the most important safety systems on the automobile. The ability of the brake system to bring a vehicle to a safe controlled stop is absolutely essential in preventing accidental vehicle damage, personal injury, and loss of life. ?mon brake system consists of brake pedal, master cylinder, disc or drum brakes, brake tubing, proportioning valve , shown in -3-1. When driver pushes down on the brake pedal, a hydraulic pressure is produced in the master cylinder, and enters into wheel cylinders through the brake tubing. accidental 意外的 proportioning valve 比例阀 Typical Hydraulic Brake System (典型液压制动系统) Fig. 2-3-1 1- master cylinder (主缸) 2- brake pedal (制动踏板) 3- rear drum brakes (后轮鼓式制动器) 4- brake tubing (制动管路) 5- front disc brakes (前***式制动器) 6- proportioning valve (比例阀) ?To identify and to correct a brake system problem, as well as to restore that system to its maximum effectiveness , requires considerable knowledge of the system's construction and operation. This includes the friction devices at each of the vehicle's wheels and the mechanical and hydraulic control systems that control the action of these friction devices. A good basic understanding of the principles of mechanical devices, hydraulic systems, and friction devices is essential. effectiveness 制动效能 considerable 相当多的?The brake system depends on the principle of friction for operation. Sliding friction is the rubbing action of one object sliding on the surface of another, such as a brake disc on a brake pad or a brake drum on a brake lining . Static friction is the resistance to the sliding of one object on the surface of another. In a brake system, when the brakes are applied there is sliding friction between the shoe and drum or the disc and pad, as long as the wheels are still turning, and there is static friction between the tire and the road surface. Upon severe braking, t