Lesson 1/Learning Event 1
FACTORS CONTROLLING RETARDATION
The amount of retardation (slowing down) obtained by the braking
system of a vehicle is affected by several factors. For wheel brakes
used on today's motor vehicles, these factors are the pressure
exerted on the braking surfaces (lining and drum), the weight carried
on the wheel, the overall radius of the wheel (the distance from the
center of the wheel to the outer tread of the tire), the radius of
the brake drum, the amount of friction between the braking surfaces,
and the amount of friction between the tire and the road. The amount
of friction between the tire and the road determines the amount of
retardation that can be obtained by the application of the brakes.
The things that affect the amount of friction between the tires and
the road are the amount and type of tread in contact with the road
surface and the type and condition of the road surface. There will
be much less friction, and thus much less retardation, on wet or icy
roads than on good dry roads.
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