The purpose of the brakes on a Formula One car is obviously to slow the car. This is achieved by converting the kinetic energy into light and heat. Like most cars they use disc brakes, a rotating disc attached to the wheels which is squeezed between two brake pads by hydraulic calipers. However, this makes the brakes become very hot, reducing their efficiency as they can absorb less energy.
Brake discs on F1 cars are made of a material called carbon-carbon, different to the carbon fibre used on the rest of the car. It is extremely lightweight so the brake discs only weigh around 1.5kg. It also has a high coefficient of friction (about 0.6, compared to the 0.3 of standard materials). This means that it is more effective at slowing the car as more kinetic energy is converted into heat energy. The brakes are capable of withstanding temperatures of up to 1200°c but cooling is essential to ensure that the brakes do not fade at the end of the race.
Air ducts are made in the inside of the wheel to allow a constant airflow over the brakes to keep them cool. Some circuits, such as Canada, with heavy braking will require larger ducts. But, larger ducts can reduce aerodynamic efficiency by as much as 1.5%. Therefore, teams will try to use smaller air ducts on circuits which require less braking. However, when following another car closely, cooling becomes less efficient and this can often result in reduced effectiveness of the brakes.
ERS and Braking
Formula One cars have an ERS system, which contains two parts to recover wasted energy. The first part is the MGU-H, recovering heat energy from the turbocharger. Another part is the MGU-K, which is effectively an upgraded version of the KERS system used previously in Formula One.
Under braking, the MGU-K converts some of the kinetic energy into electrical energy, which can be deployed during the lap. It works as a generator, attached to the crankshaft of the engine.