Questions and answers to the Maintenance and car control

high temperature ( it must not start to boil, which would cause air in the brakes) which is generated when
using brakes (over 200 deg.C). This resistance decreses with time (due to atmospheric humidity).
15. Describe the purpose of power brakes and power steering and why the engine
must not be switched off during travel.
Power brakes/brake booster (pressure power brakes – uses pressure in the inlet pipe of the engine)
facilitates the control of the brake pedal and reduces the amount of pedal pressure needed for braking.
Power steering/steering booster for lorries (trucks) as well as for passenger cars makes it easier to handle
the steering wheel when driving, especially when parking and manoeuvring in a confined space. In
passenger cars there are special servos which influence the mechanism of steering.
Power brakes and power steering work only when the engine is in motion hence it is not recommended to
switch off the engine during travel. Morevoer, when the ignition is off, some electrical systems (e.g. turn
signals) do not work and there is an increased risk of sudden wheel lock.
16. Describe the difference between the disc brake and drum brake, their
advantages and disadvantages.
Disc brakes – braking effect is caused by pressing friction parts (i.e. brake pads located in the brake
caliper) against the sides of the brake disc. They are mainly used for front axle of the car. The
advantages include:
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Good braking effect and shorter braking distance
Better heat removal
Smaller weight and size
Easier control and change of lining.
Bicycle brakes work on the same principle – rubber segments (=brake pads) press against the wheel
rim (=disc).
Drum brakes - consists of a set of shoes (with lining on the external part) and brake drum. When the