Working principle of car braking system

　　The automotive braking system plays a vital role in ensuring safe vehicle operation, and electronic control of the braking system significantly enhances the vehicle's active safety. For automotive products, the automotive braking system is closely related to personal safety and economic efficiency. Currently, automotive braking systems are widely used in automotive design, but there are various types of braking systems used in automobiles. This article will introduce the function and classification of automotive braking systems.

　　I. Functions of the Automotive Braking System

　　The function of the automotive braking system is to: force a moving vehicle to decelerate or stop according to the driver's requirements; to keep a stationary vehicle stable when parked under various road conditions (including on slopes); and to maintain a stable speed when driving downhill.

　　Only external forces acting on the vehicle and opposite to the direction of travel can cause braking. The magnitude of these forces is random and uncontrollable, so the vehicle must be equipped with a series of specialized devices to achieve the above functions.

　　The automotive braking system refers to the specialized braking mechanism installed on a vehicle to technically ensure safe driving and improve average speed. Generally, an automotive braking system includes two independent systems: a service brake and a parking brake. The service brake is operated by the driver's foot and is also known as the foot brake. The parking brake is operated by the driver's hand and is also known as the hand brake.

　　The function of the service brake is to decelerate a moving vehicle or bring it to a stop within the shortest distance. The function of the parking brake is to keep a vehicle stationary on various road surfaces. However, in emergencies, both braking systems can be used simultaneously to enhance braking effect. For special-purpose vehicles and vehicles frequently operating in mountainous areas, prolonged and frequent braking can cause overheating of the service brake. Therefore, these vehicles often have various types of auxiliary braking systems to stabilize vehicle speed downhill.

　　According to the braking energy source, braking systems can be divided into three types: manual, power, and servo braking systems. Manual braking systems use the driver's physical strength as the braking energy source; power braking systems use air pressure or hydraulic pressure converted from engine power as the braking energy source; and servo braking systems use both human power and engine power as the braking energy source. In addition, according to the transmission method of braking energy, braking systems can be divided into mechanical, hydraulic, pneumatic, and electromagnetic types.

　　In various automotive braking systems, the brake is the component that generates the force to prevent vehicle movement or motion tendency. Currently, most automotive brakes are friction brakes, meaning that the braking torque preventing vehicle movement comes from friction between the fixed component and the rotating working surface.

　　II. Classification of Automotive Braking System Types

　　1. Drum Brakes

　　Drum brakes are a traditional braking system. Their working principle can be vividly described using a coffee cup. The brake drum is like the coffee cup. When you insert five fingers into a rotating coffee cup, your fingers are the brake pads. By spreading your fingers outwards and rubbing against the inner wall of the coffee cup, the coffee cup will stop rotating. Simply put, drum brakes in a car consist of a brake pump, piston, brake pads, and drum chamber. During braking, high-pressure brake fluid from the brake caliper pushes the piston, applying force to two semi-circular brake shoes, pressing them against the inner wall of the drum, and using friction to prevent the brake drum from rotating, thus achieving braking.

　　2. Disc Brakes

　　Similarly, the working principle of disc brakes can be described using a disc. When you pinch a rotating disc with your thumb and index finger, the disc will also stop rotating. Disc brakes in a car consist of a brake fluid pump, a brake disc connected to the wheel, and a brake caliper on the disc. During braking, high-pressure brake fluid pushes the pistons in the caliper, pressing the brake pads against the brake disc to produce a braking effect.

　　Disc brakes are sometimes called disc brakes and are divided into two types: ordinary disc brakes and ventilated disc brakes.

　　Ventilated disc brakes have a gap between the two brake discs, allowing airflow to pass through the gap. Some ventilated discs also have many circular ventilation holes drilled on the disc surface, or ventilation slots cut on the disc surface, or rectangular ventilation holes pre-formed. Ventilated disc brakes utilize airflow, resulting in better cooling than ordinary disc brakes. The main advantages of disc brakes are rapid braking at high speeds, better heat dissipation than drum brakes, good braking performance consistency, and easy installation of advanced electronic equipment like ABS. The main advantages of drum brakes are less brake pad wear, lower cost, and easy maintenance. Because the absolute braking force of drum brakes is much higher than that of disc brakes, they are commonly used on rear-wheel-drive trucks.

　　3. Disc Brakes

　　In recent years, vehicle speeds have been continuously increasing, and the gross weight of trucks and large buses has been continuously increasing. In addition, the lower center of gravity and widespread use of small-diameter, wide-section tires in passenger cars have limited the installation position of the brakes. Therefore, the use of disc brakes with better braking thermal stability is increasing in heavy-duty trucks and passenger cars. Disc brakes can be divided into caliper disc brakes and full disc brakes.

　　Conclusion

　　Since the invention of the automobile, the automotive braking system has played a vital role in vehicle safety. The automotive braking system is crucial to our lives, and accidents caused by braking problems are common in daily driving. Understanding the function and classification of the braking system is beneficial for the detection and troubleshooting of automotive braking systems, ensuring safe vehicle operation.