2024年3月22日发(作者：鲜书慧)

Automobile Brake System汽车制动系统

The braking system is the most important system in cars。 If the brakes fail, the result

can be disastrous。 Brakes are actually energy conversion devices, which convert the

kinetic energy (momentum） of the vehicle into thermal energy (heat).When stepping

on the brakes， the driver commands a stopping force ten times as powerful as the

force that puts the car in motion. The braking system can exert thousands of pounds of

pressure on each of the four brakes。

Two complete independent braking systems are used on the car. They are the service

brake and the parking brake。

The service brake acts to slow， stop， or hold the vehicle during normal driving。

They are foot—operated by the driver depressing and releasing the brake pedal。 The

primary purpose of the brake is to hold the vehicle stationary while it is unattended。

The parking brake is mechanically operated by when a separate parking brake foot

pedal or hand lever is set.

The brake system is composed of the following basic components: the “master

cylinder” which is located under the hood, and is directly connected to the brake

pedal， converts driver foot’s mechanical pressure into hydraulic pressure. Steel

“brake lines” and flexible “brake hoses” connect the master cylinder to the “slave

cylinders” located at each wheel. Brake fluid, specially designed to work in extreme

conditions, fills the system. “Shoes” and “pads" are pushed by the slave cylinders to

contact the “drums” and “rotors” thus causing drag, which (hopefully） slows the car.

The typical brake system consists of disk brakes in front and either disk or drum

brakes in the rear connected by a system of tubes and hoses that link the brake at each

wheel to the master cylinder （Figure）。

Basically， all car brakes are friction brakes。 When the driver applies the brake， the

control device forces brake shoes, or pads, against the rotating brake drum or disks at

wheel. Friction between the shoes or pads and the drums or disks then slows or stops

the wheel so that the car is braked。

In most modern brake systems （see Figure 15.1)， there is a fluid-filled cylinder,

called master cylinder, which contains two separate sections， there is a piston in each

section and both pistons are connected to a brake pedal in the driver’s compartment。

When the brake is pushed down, brake fluid is sent from the master cylinder to the

wheels.

At the wheels， the fluid pushes shoes， or pads, against revolving drums or disks.

The friction between the stationary shoes, or pads, and the revolving drums or disks

slows and stops them。 This slows or stops the revolving wheels, which, in turn, slow

or stop the car.

The brake fluid reservoir is on top of the master cylinder. Most cars today have a

transparent r reservoir so that you can see the level without opening the cover。 The

brake fluid level will drop slightly as the brake pads wear. This is a normal condition

and no cause for concern. If the level drops noticeably over ashort period of time or

goes down to about two thirds full， have your brakes checked as soon as possible。

Keep the reservoir covered except for the amount of time you need to fill it and never

leave a cam of brake fluid uncovered。 Brake fluid must maintain a very high boiling

point。 Exposure to air will cause the fluid to absorb moisture which will lower that

boiling point。

The brake fluid travels from the master cylinder to the wheels through a series of

steel tubes and reinforced rubber hoses. Rubber hoses are only used in places that

require flexibility， such as at the front wheels, which move up and down as well as

steer。 The rest of the system uses non—corrosive seamless steel tubing with special

fittings at all attachment points. If a steel line requires a repair, the best procedure is to

replace the compete line。 If this is not practical， a line can be repaired using special

splice fittings that are made for brake system repair。 You must never use copper

tubing to repair a brake system。 They are dangerous and illegal。

Drum brakes, it consists of the brake drum, an expander， pull back springs, a

stationary back plate, two shoes with friction linings， and anchor pins。 The

stationary back plate is secured to the flange of the axle housing or to the steering

knuckle. The brake drum is mounted on the wheel hub。 There is a clearance between

the inner surface of the drum and the shoe lining。 To apply brakes, the driver pushes

pedal， the expander expands the shoes and presses them to the drum。 Friction

2024年3月22日发(作者：鲜书慧)

Automobile Brake System汽车制动系统

The braking system is the most important system in cars。 If the brakes fail, the result

can be disastrous。 Brakes are actually energy conversion devices, which convert the

kinetic energy (momentum） of the vehicle into thermal energy (heat).When stepping

on the brakes， the driver commands a stopping force ten times as powerful as the

force that puts the car in motion. The braking system can exert thousands of pounds of

pressure on each of the four brakes。

Two complete independent braking systems are used on the car. They are the service

brake and the parking brake。

The service brake acts to slow， stop， or hold the vehicle during normal driving。

They are foot—operated by the driver depressing and releasing the brake pedal。 The

primary purpose of the brake is to hold the vehicle stationary while it is unattended。

The parking brake is mechanically operated by when a separate parking brake foot

pedal or hand lever is set.

The brake system is composed of the following basic components: the “master

cylinder” which is located under the hood, and is directly connected to the brake

pedal， converts driver foot’s mechanical pressure into hydraulic pressure. Steel

“brake lines” and flexible “brake hoses” connect the master cylinder to the “slave

cylinders” located at each wheel. Brake fluid, specially designed to work in extreme

conditions, fills the system. “Shoes” and “pads" are pushed by the slave cylinders to

contact the “drums” and “rotors” thus causing drag, which (hopefully） slows the car.

The typical brake system consists of disk brakes in front and either disk or drum

brakes in the rear connected by a system of tubes and hoses that link the brake at each

wheel to the master cylinder （Figure）。

Basically， all car brakes are friction brakes。 When the driver applies the brake， the

control device forces brake shoes, or pads, against the rotating brake drum or disks at

wheel. Friction between the shoes or pads and the drums or disks then slows or stops

the wheel so that the car is braked。

In most modern brake systems （see Figure 15.1)， there is a fluid-filled cylinder,

called master cylinder, which contains two separate sections， there is a piston in each

section and both pistons are connected to a brake pedal in the driver’s compartment。

When the brake is pushed down, brake fluid is sent from the master cylinder to the

wheels.

At the wheels， the fluid pushes shoes， or pads, against revolving drums or disks.

The friction between the stationary shoes, or pads, and the revolving drums or disks

slows and stops them。 This slows or stops the revolving wheels, which, in turn, slow

or stop the car.

The brake fluid reservoir is on top of the master cylinder. Most cars today have a

transparent r reservoir so that you can see the level without opening the cover。 The

brake fluid level will drop slightly as the brake pads wear. This is a normal condition

and no cause for concern. If the level drops noticeably over ashort period of time or

goes down to about two thirds full， have your brakes checked as soon as possible。

Keep the reservoir covered except for the amount of time you need to fill it and never

leave a cam of brake fluid uncovered。 Brake fluid must maintain a very high boiling

point。 Exposure to air will cause the fluid to absorb moisture which will lower that

boiling point。

The brake fluid travels from the master cylinder to the wheels through a series of

steel tubes and reinforced rubber hoses. Rubber hoses are only used in places that

require flexibility， such as at the front wheels, which move up and down as well as

steer。 The rest of the system uses non—corrosive seamless steel tubing with special

fittings at all attachment points. If a steel line requires a repair, the best procedure is to

replace the compete line。 If this is not practical， a line can be repaired using special

splice fittings that are made for brake system repair。 You must never use copper

tubing to repair a brake system。 They are dangerous and illegal。

Drum brakes, it consists of the brake drum, an expander， pull back springs, a

stationary back plate, two shoes with friction linings， and anchor pins。 The

stationary back plate is secured to the flange of the axle housing or to the steering

knuckle. The brake drum is mounted on the wheel hub。 There is a clearance between

the inner surface of the drum and the shoe lining。 To apply brakes, the driver pushes

pedal， the expander expands the shoes and presses them to the drum。 Friction