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1、学习内容,本节课学习内容、目标和重点难点,学习目标,难点重点,Chapter 5 Braking Systems,1.掌握制动系统的基本组成、类型、ABS系统主要零件的英文名称 2.提高翻译技巧，能较熟练翻译课文,1.重点是英文专业术语记忆 2.难点是生词偏多、ABS控制原理原理,Chapter 5 Braking Systems 5.1 Overview of Braking Systems,Chapter 5 Braking Systems 5.1 Overview of Braking Systems,Chapter 5 Braking Systems 5.1 Overview of B
2、raking Systems,Chapter 5 Braking Systems 5.1 Overview of Braking Systems,The braking system is very important to a car. If your brakes dont work properly, the result can be disastrous. Brakes are actually energy conversion devices, which convert the kinetic energy of the vehicle into thermal energy.
3、,Chapter 5 Braking Systems 5.1 Overview of Braking Systems,There are three kinds of braking systems: service brake system, parking brake system and additional retarder braking system. The service brake system is the main braking system used to slow down or even stop the car thats running at a high s
4、peed and guarantee the safety of passengers. It is foot-operated by the driver depressing and releasing the brake pedal. A parking brake system can prevent the auto slipping away from its parking place, even if it is parked on a steep slope. It is also called the hand brake.,Chapter 5 Braking System
5、s 5.1 Overview of Braking Systems,The braking system is composed of the brake and its control mechanisms. A hydraulic brake system mainly consists of the brake pedal, the vacuum booster, the master cylinder, the brake line and the brake, as shown in Fig. 5-1. To increase safety, most modern car brak
6、ing systems are broken into two circuits, with two wheels on each circuit.,Fig. 5-1 Hydraulic braking system,Chapter 5 Braking Systems 5.1 Overview of Braking Systems,There are two main types of brakes: drum brake and disc brake. Basically, all car brakes are friction brakes. When the driver applies
7、 the brake, the control device forces brake shoes or pads against the rotating brake drums or discs at wheels. Friction between the shoes or pads and the drums or discs then slows or stops the wheels so that the car is braked.,Chapter 5 Braking Systems 5.2 Brakes,1. Drum Brake A drum brake is usuall
8、y composed of the brake backing plate, the wheel cylinder, the brake shoes, the brake drum and the brake clearance adjusting mechanisms, as shown in Fig. 5-2. It uses an internal expanding brake shoe with the lining attached, working within the confines of a rotating brake surface called a brake dru
9、m. The brake shoe diameter is expanded to contact the brake surface by a hydraulic cylinder that is referred to as a wheel cylinder. With drum brake, the fluid is forced into the wheel cylinder which pushes the brake shows out so that the friction linings are pressed against the drum, and cause the
10、wheel to stop (Fig. 5-3).,Chapter 5 Braking Systems 5.2 Brakes,Fig. 5-2 Drum Brake,Chapter 5 Braking Systems 5.2 Brakes,Fig. 5-3 Principle of Drum Brake,Chapter 5 Braking Systems 5.2 Brakes,2 .Disc Brake The main parts of a disc brake include the brake cylinder, the brake disc and the brake calipers
11、. The disc brake is a lot like the brakes on a bicycle. Bicycle brakes have a caliper, which squeezes the brake pads against the wheel. In a disc brake, the brake pads squeeze the rotor instead of the wheel, and the force is transmitted hydraulically instead of through a cable. Friction between the
12、pads and the disc slows the disc down (Fig. 5-4 and 5-5).,Chapter 5 Braking Systems 5.2 Brakes,Fig. 5-4 Disc Brake Fig. 5-5 Principle of Disc Brake,Chapter 5 Braking Systems 5.3 Brake Transmissions,1. Master Cylinder In the modern braking system, the master cylinder is power-assisted by the engine.
13、The master cylinder is located in the engine compartment on the firewall, directly in front of the drivers seat. A typical master cylinder has actually two completely separate master cylinders in one housing, each handling two wheels. That is to say, if one side fails, you will still be able to stop
14、 the car. 2.Brake Fluid Brake fluid is special oil that has specific properties. It is designed to withstand cold temperatures without thickening as well as very high temperatures without boiling. If the brake fluid boils, it would cause you to have a spongy pedal and the car would be hard to stop.,
15、Chapter 5 Braking Systems 5.3 Brake Transmissions,3.Booster The power brake booster （Fig. 5-6） is mounted on the firewall directly behind the master cylinder and, along with the master cylinder, is directly connected with the brake pedal. Its purpose is to amplify the available foot pressure applied
16、 to the brake pedal so that the amount of foot pressure required to stop even the largest vehicle is minimal.,Fig. 5-6 Booster,Chapter 5 Braking Systems 5.4 Anti-lock braking systems,An anti-lock braking system (commonly known as ABS) is a system on motor vehicles which prevents the wheels from locking while braking. Its function is to prevent wheel from locking when applying prompt braking, the biggest adhesive force between the tire and the ground and the high s
