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Thursday 2 May 2013

Brake

A brake is a mechanical device or system used to slow down or stop the motion of a vehicle or machine. In the context of automobiles, brakes are crucial for controlling the speed and stopping the vehicle when necessary.


The concept of braking systems for vehicles has a long history, and the development of brakes has evolved over time. The first brakes were not specifically designed for automobiles as we know them today, but for other types of transport.

The development of early braking systems predates the Roman Empire when simple brake mechanisms were used on wheeled carts to assist with slowing down or stopping. A mechanism involving wooden blocks pressed directly against the wheels by an effort-multiplying lever, is an example of one of the early braking systems.

These basic braking systems were crucial in reducing the reliance on the strength of horses alone to control the speed of carts. The lever provided a mechanical advantage, allowing the driver to apply force more effectively and slow down or stop the vehicle.

The first practical application of a braking system for a vehicle is often credited to the English "Father of Railways," George Stephenson. In the early 19th century, around 1815, Stephenson developed a steam-powered locomotive known as the "Blücher." This locomotive featured a primitive braking system that used a chain to apply pressure on the wheels, slowing down the train.

For horse-drawn carriages, early braking systems involved using various mechanisms like wooden blocks or shoes applied to the wheels to create friction and slow down the vehicle.

American entrepreneur and engineer George Westinghouse, patented the compressed-air brake on March 5, 1872. .Before his invention, there was no easy way to quickly stop the extremely heavy freight trains that transported goods over land. Brakemen scrambled over the tops of moving cars to activate hand brakes on each one. The system was unreliable, resulting in frequent derailments, and many brakemen were killed or maimed after falling from trains. The air brake solved all of those problems.

Control handle and valve for a Westinghouse Air Brake

The first production car with hydraulic brakes (i.e. using pipes and fluid rather than cables to activate the brakes) was the 1920 Duesenberg, an American luxury car with a "straight eight" engine. Chrysler brought the now universal feature to mass-produced cars in 1924.

Formula One racing is where the most advanced brakes are found. During 1997, German driver Heinz-Harald Frentzen recorded a force of 5.99G under braking. This is around six times the braking performance of a conventional road car and meant that Heinz-Harald’s 65kg body momentarily weighed nearly 390kg. To achieve this deceleration he had to push the brake pedal of his Williams-Renault with a pressure of 150kg.

In 1950, Dunlop announced the disc brake. They helped Jaguar to win the Le Mans 24 Hour race in 1953 were referred to in the press of the time as "plate brakes". The term "discs" came later.

The 1967 Porsche 911S was the first production car to feature ventilated disc brake rotors. Now common, these rotors have cooling channels running between the two friction surfaces to give better cooling and therefore better resistance to brake fade during heavy applications.

Brakes work by creating friction, converting that speedy momentum into heat. In fact, brake discs can reach scorching temperatures of over 500°C during heavy braking!

Most modern cars use disc brakes, where pads squeeze against a rotating disc. But some vehicles, especially older ones, still rock drum brakes, where shoes press against the inside of a rotating drum. Each has its own advantages and quirks.


Forget muscle power! Most car brakes rely on a hydraulic system. When you press the pedal, fluid is pumped to the brakes, multiplying your force and making stopping effortless.

If a car is travelling at 55 miles per hour it will travel 56 feet before the driver can shift his foot from the accelerator to the brake. 

The power generated by the braking system of even a modest family car can exceed 500bhp (375kW), outstripping the engine output of virtually everything on the road.

That annoying squealing you hear sometimes? Those are actually metal "squealers" embedded in the brake pads, warning you they're nearing the end of their life and need replacing. Don't ignore them!

Hybrid and electric cars use their brakes to their advantage. When you slow down, the energy is captured and partially recharged into the battery, boosting efficiency.

Sources Google Bard, Motorcare.com

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