Page 22 - 05. Subyek Teknik Mesin - Automobile Mechanical and Electrical Systems Automotive Technology Vehicle Maintenance and Repair (Vehicle Maintenance Repr Nv2) by Tom Denton

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inlet manifold and is fi red in each cylinder in turn. The resulting expanding gases
push on pistons and connecting rods which are on cranks, just like a cyclist’s
legs driving the pedals, and this makes a crankshaft rotate. The pulses of power
from each piston are smoothed out by a heavy fl ywheel. Power leaves the engine
through the fl ywheel, which is fi tted on the end of the crankshaft, and passes to
the clutch. The spent gases leave via the exhaust system.

1.1.5.2 Electrical
The electrical system covers many aspects such as lighting, wipers and
instrumentation. A key component is the alternator ( Fig. 1.18 ) which, driven by
the engine, produces electricity to run the electrical systems and charge the Figure 1.18 A modern alternator.
(Source: Bosch Press)
battery. A starter motor takes energy from the battery to crank over and start the
engine. Electrical components are controlled by a range of switches. Electronic
systems use sensors to sense conditions and actuators to control a variety of
things – in fact, on modern vehicles, almost everything.

1.1.5.3 Chassis
This area is made up of the braking, steering and suspension systems as well as
the wheels and tyres. Hydraulic pressure is used to activate the brakes to slow
down or stop the vehicle. Rotating discs are gripped between pads of friction
lining ( Fig. 1.19 ). The handbrake uses a mechanical linkage to operate parking
brakes. Both front wheels are linked mechanically and must turn together to
provide steering control. The most common method is to use a rack and pinion.
The steering wheel is linked to the pinion and as this is turned it moves the rack
to and fro, which in turn moves the wheels. Tyres also absorb some road shock
and play a very important part in road holding. Most of the remaining shocks
and vibrations are absorbed by springs in the driver and passenger seats. The
Figure 1.19 Disc brakes and part of the
springs can be coil type and are used in conjunction with a damper to stop them suspension system
oscillating (bouncing up and down too much).

1.1.5.4 Transmission

In this area, the clutch allows the driver to disconnect drive from the engine and
Key fact
move the vehicle off from rest. The engine fl ywheel and clutch cover are bolted
together so the clutch always rotates with the engine, and when the clutch A gearbox is needed because an
pedal is raised drive is passed to the gearbox. A gearbox is needed because engine produces power only when
turning quite quickly.
an engine produces power only when turning quite quickly. The gearbox allows
the driver to keep the engine at its best speed. When the gearbox is in neutral,
power does not leave it. A fi nal drive assembly and differential connect the drive
to the wheels vial axles or driveshafts ( Fig. 1.20 ). The differential allows the
driveshafts and hence the wheels to rotate at different speeds when the vehicle
is cornering.

1.1.6 Summary

The layout of a vehicle, such as where the engine is fi tted and which wheels are
driven, varies, as do body styles and shapes. However, the technologies used
in the four main areas of a vehicle are similar no matter how it is described.
These are:
the engine system
●
the electrical system
●
the chassis system
●
Figure 1.20 Differential and fi nal drive
the transmission system. components
●