A Closer Look At Brakes And Braking

There is more than one way of bringing a modern car or truck to a halt. Jake Venter discusses the various brake systems used in today’s vehicles.

- Jake Venter

When you brake a vehicle, the front suspension dips and the rear rises. The braking force is applied at the road surface, but the inertia of the car acts at the centre of gravity, some distance above the road. This apparent weight transfer gets worse the harder you brake, and explains why many cars become unstable and skid during emergency stopping. ABS brakes were developed to prevent wheels from locking, and as a result usually shorten braking distances.

Most ABS-equipped cars can be brought to a halt from 100km/h in 2,8 seconds, an average deceleration of 1g, but the average sedan takes about 10 seconds (0,3g) to accelerate from zero to this speed. This demonstrates that converting heat energy into mechanical energy (with an engine) is more difficult than converting mechanical energy into heat (with brakes).