Brakes

Overview of Brakes

A brake is a mechanical device designed to inhibit motion by absorbing energy from a moving system. It is primarily used to slow down or stop a moving vehicle, wheel, axle, or to prevent its motion altogether. Most brakes accomplish this through friction between two surfaces, converting kinetic energy into heat, although other methods of energy conversion are also employed.

Types of Brakes

Frictional Brakes

Frictional brakes are the most common type and can be divided into:

• Shoe or Pad Brakes: These use an explicit wear surface.
• Drum Brakes: Use brake shoes that press against the inner surface of a rotating drum.
• Disc Brakes: Use brake pads that pinch a rotating disc.
• Hydrodynamic Brakes: Use friction in a working fluid and do not explicitly wear.

Pumping Brakes

Pumping brakes utilize a pump as part of the braking mechanism:

• Internal Combustion Engines: Can use engine braking by stopping the fuel supply and increasing internal pumping losses.
• Jake Brakes: Increase pumping losses significantly.

Electromagnetic Brakes

Electromagnetic brakes use electromagnetic induction to create resistance:

• Regenerative Brakes: Convert kinetic energy into electrical energy, which can be stored for later use.
• Eddy Current Brakes: Use magnetic fields to convert kinetic energy into electric current and then heat.

Characteristics of Brakes

Brakes are often described by several key characteristics:

• Peak Force: The maximum decelerating effect obtainable.
• Continuous Power Dissipation: The maximum amount of energy that can be dissipated without failure.
• Fade: Reduction in braking effectiveness due to heat.
• Smoothness: Consistency of the braking force.
• Power: The relationship between human application force and braking force.
• Pedal Feel: The subjective perception of brake power output as a function of pedal travel.
• Drag: The amount of resistance when the brake is not applied.
• Durability: The longevity of the brake components.
• Weight: The impact of brake weight on vehicle performance.
• Noise: The sound produced by the brakes during operation.

Foundation Components

Foundation components are the brake-assembly parts at the wheels, forming the basis of the brake system. The three main types are:

• S Cam Brakes
• Disc Brakes
• Wedge Brakes

Brake Boost

Modern vehicles often use a vacuum-assisted brake system to increase the force applied by the operator. In heavier vehicles, compressed air is used to boost brake power.

Noise and Inefficiency

Brakes can contribute to noise pollution and inefficiency due to energy loss during braking. Minimizing brake use can improve fuel economy.

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History of Brakes

• 1890s: Wooden block brakes became obsolete with the introduction of rubber tires.
• 1960s: Drum brakes were replaced by disc brakes in some cars.
• 1966: ABS was introduced in the Jensen FF grand tourer.
• 1978: Bosch and Mercedes updated the ABS for the Mercedes S-Class.
• 2005: ESC became compulsory for certain vehicles in Quebec.
• 2013: UNECE regulation 131 for AEBS in heavy vehicles.
• 2020: UNECE regulation 152 for AEBS in light vehicles.
• 2022: AEBS became mandatory in the EU for new vehicles.

Advanced Braking Systems

• Brake Assist System (BAS): Enhances braking during emergency situations.
• Advanced Emergency Braking Systems (AEBS): Automatically detect potential collisions and activate braking.

Summary Table

Brakes are an essential component of vehicle safety and performance, with various types and characteristics tailored to specific applications and requirements.

Brake (Wikipedia)

This article is about the vehicle component. For other uses, see Brake (disambiguation).

Not to be confused with Break.

A brake is a mechanical device that inhibits motion by absorbing energy from a moving system. It is used for slowing or stopping a moving vehicle, wheel, axle, or to prevent its motion, most often accomplished by means of friction.