Modern brakes were invented in the late 19th century, around
the same time as the tyre. Up until then, vehicles had wooden wheels that were
stopped by large wooden blocks, lowered into position by the driver using a
simple lever system. When tyres were invented, the wooden block system wasn’t
good enough to stop them at the higher speeds they could achieve, which meant
that a new braking system had to be invented.
To see the basic principles of modern braking, it is easiest
to look at a bicycle. Basically, when you put pressure on the brakes, the
pressure is transferred through cables to pull small pads onto the side of the
tyres, and the force of the friction against the tyres causes them to stop.
In fact, Cars originally used this very same cable system, but
it was found not to work so well at high speeds. Instead, the cables were
replaced with hydraulic fluid, which works to transfer the pressure the driver
puts on the pedal to the brakes. This works because the fluid cannot get much
smaller when pressure is put on it, meaning that pressure at one end is
transferred to the other – much like water flowing through a pipe. However, if
this brake fluid leaks even a little, then the brakes may not work properly any
more, which is why it’s very important to check your brake fluid regularly.
Of course, in modern cars, there are other mechanisms apart
from pure pressure to help you brake. Most cars now have a vacuum system to
create more friction in the brakes, and a servo system that uses the car’s own
speed to help your pressure have more of an impact.
One word of warning, though: some cars now have fully
computerised brakes, where pushing on the pedal sends an electrical signal to
turn on electrically-powered brakes. While this makes it much easier to brake,
it is also more prone to failure, meaning that if your car’s computer breaks
you might find it impossible to stop. Until this technology has been around a
little longer, it’s probably best to stick to traditional mechanical braking
methods.

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