Lesson 1/Learning Event 1
The power needed to brake a vehicle is equal to that needed to make
it go. However, for safety reasons, brakes must be able to stop the
car in a very short distance. As an example, a passenger car
equipped with an 80HP engine can normally accelerate from a
standstill to 60 MPH in about 36 seconds. On the other hand, the
brakes must be able to decelerate the vehicle from 60 MPH to a stop
in 4 1/2 seconds. You can therefore see the braking force is about
eight times greater than the power developed by the engine.
Each part in the braking system must operate with a very positive
action to accomplish this tremendous braking effort. The job of a
wheeled vehicle mechanic is to maintain the braking components in a
state of repair that ensures serviceable brakes when needed. For you
to keep brake system components in a working shape, you must
understand how the system works. In this lesson, we will discuss the
principles of operation for components contained in various types of
braking systems.
Braking action is the use of a controlled force to slow the speed of
or stop a moving object, in this case a vehicle. It is necessary to
know what friction is to understand braking action.
Friction is the resistance to movement between two surfaces or
objects that are touching each other. An example of friction is the
force which tries to stop your hand as you apply pressure and slide
it across a table or desk. This means that by forcing the surface of
an object that is not moving (stationary) against a moving object's
surface, the resistance to movement or the rubbing action between the
two surfaces of the objects will slow down the moving surface.
Automotive vehicles are braked in this manner.
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