شنبه ۰۷ مهر ۰۳ | ۱۵:۲۱ ۷ بازديد
22
weight is at the front
• Front wheel drive adds further
advantages particularly if the
engine is mounted sideways on
(transversely).
• More room in the passenger
compartment
• Power unit can be made as a
complete unit
• Drive acts in the same direction
that the steered wheels are
pointing
Front engine RWD Rear wheel drive
from a front engine was the method
used for many years. Some
manufacturers have continued its use,
BMW for example. A long propeller
shaft from the gearbox to the final
drive, which is part of the rear axle, is
the main feature. The propshaft has
universal joints to allow for suspension
movement. This layout has some
advantages.
• Weight transfers to the rear
driving wheels when accelerating.
• Complicated constant velocity
23
joints such as used by front wheel
drive vehicles, are not needed.
Four wheel drive combines all the good
points mentioned above but does make
the vehicle more complicated and
therefore expensive. The main
difference with four wheel drive is
that an extra gearbox known as a
transfer box is needed to link the
front and rear wheel drive.
Rear engine The rear engine design
has not been very popular but it was
used for the best-selling car of all
time - the VW beetle. The advantages
are that weight is placed on the rear
wheels giving good grip and the power
unit and drive can be all one assembly.
One down side is that less room is
available for luggage in the front. The
biggest problem is that handling is
affected because of less weight on
the steered wheels. Flat type engines
are the most common choice for this
type of vehicle.
24
Mid-engine Fitting the engine in the
mid position of a car has one major
disadvantage; it takes up space inside
the vehicle. This makes it impractical
for most ‘normal’ vehicles. However,
the distribution of weight is very good.
This makes it the choice of high
performance vehicle designers. A good
example is the Ferrari Testarossa.
Mid-engine is used to describe any
vehicle where the engine is between
the axles, even if it is not in the
middle!
Chassis Vehicle chassis can be of two main types: separate or
integrated. Separate chassis are usually used on heavier
vehicles. The integrated type, often called monocoque, is used
for almost all cars.
The two types are shown here.
25
Body Shown here is a car and a list of body panel names. Click
the buttons in turn to reveal the panel or other body
component.
Front engine FWD detailed layout Front engine front wheel
drive is now the most common layout, so this will be used for a
more detailed explanation. All layout designs however, have
similar major components and these operate in much the same
way. The main systems of a front engine front wheel drive car
are as follows:
• Power train, consisting of; Engine, clutch, gearbox, final
drive and drive shafts (engine and transmission system
combined).
• Braking system
• Steering system
• Suspension system
• Electrical system
26
Power train There are various
groupings of engine, clutch,
gearbox and final drive. One of
the most common is shown
here. The basic power flow,
meaning the way in which
energy is passed through the
system, is as follows:
As fuel and air mixture is
ignited above the pistons, they
push on connecting rods which
are on cranks, just like a
cyclists legs driving pedals.
This makes the crankshaft
rotate. Power is passed
through the clutch and then
through a gearbox. The output
of the gearbox is linked to the
final drive. This then applies
the power to the front wheels
through drive shafts. These
shafts have joints so they can
move with the steering and
suspension.
27
Engine A fuel air mixture
enters through an inlet
manifold and is fired in each
cylinder in turn. This expands
and pushes down on the piston.
The spent gases leave via the
exhaust system. The power is
applied to the crankshaft. The
pulses of power from each
piston are smoothed out by a
heavy flywheel. Power leaves
the engine through the
flywheel which is fitted on the
rear of the rotating
crankshaft and passes to the
clutch.
Clutch The clutch is to allow
the driver to disconnect drive
from the engine and move the
vehicle off from rest. The
engine flywheel and clutch
cover are bolted together so
the cover always rotates with
the engine. A pressure plate
and clutch springs are mounted
on the cover. A gearbox shaft
28
is fixed so that it rotates with
the clutch driven plate but it
can slide slightly. The clutch,
or driven plate has friction
linings. The clutch is engaged
when the pedal is up because
the clutch springs and pressure
plate hold the driven plate
against the flywheel. This
makes the drive pass to the
gearbox. To disengage the
clutch the pedal is pressed
down. A release bearing makes
the pressure plate move back
away from the flywheel, and
frees the driven plate from
the flywheel. No drive is now
passed to the gearbox.
Gearbox A gearbox is needed
because an engine produces
power only when turning quite
fast. The gearbox allows the
driver to keep the engine at its
best speed. When the gearbox
is in neutral, power does not
leave it. When the gearbox is
29
in first gear, power is
transferred from a small to a
larger gear, and then out to
the final drive. Different
stages of speed reduction
(second and third gear) are
created using different sizes
of gear. Less speed out of the
gearbox has a higher turning
force (torque) because the
engine is running faster.
Fourth gear normally makes
the output shaft turn at the
same speed as the engine.
Fifth gear makes the output
shaft run faster than the
engine for economical higher
speed driving.
Final drive The final drive
assembly of a front wheel
drive vehicle has two main
tasks:
• Further speed reduction
of about 3:1. This is
output gear to pinion ratio
which will vary with
30
different types of
vehicles and engines.
• Different speeds to the
AUTOMOTIVE TECHNICIAN TRAINING – © TOM DENTON
31
Braking system Hydraulic
brakes are used to slow down
or stop the vehicle. The hand
brake uses a mechanical linkage
to operate parking brakes. The
main brakes work on all four
wheels and the hand brake
usually just on the rear. The
hydraulic principle is that foot
pressure on the brake pedal
pushes fluid under pressure to
all four wheels. Braking
materials (friction linings) are
pressed against rotating
surfaces, slowing them down
thereby slowing down the
vehicle. Discs, normally on the
front, are gripped between
pads of friction lining. Drums,
normally on the rear, are
gripped on their inside
surfaces by shoes covered with
friction lining. This is the most
common arrangement but some
vehicles have all drums or all
discs.
31
Braking system Hydraulic
brakes are used to slow down
or stop the vehicle. The hand
brake uses a mechanical linkage
to operate parking brakes. The
main brakes work on all four
wheels and the hand brake
usually just on the rear. The
hydraulic principle is that foot
pressure on the brake pedal
pushes fluid under pressure to
all four wheels. Braking
materials (friction linings) are
pressed against rotating
surfaces, slowing them down
thereby slowing down the
vehicle. Discs, normally on the
front, are gripped between
pads of friction lining. Drums,
normally on the rear, are
gripped on their inside
surfaces by shoes covered with
friction lining. This is the most
common arrangement but some
vehicles have all drums or all
discs.
32
Steering system Both front
wheels are linked mechanically
and must turn together to
provide steering control. The
image here shows a rack and
pinion. The steering wheel is
linked to the pinion and as this
is turned it moves the rack to
and fro. This moves both the
wheels. Many vehicles have
power assisted steering which
uses a pump driven by the
engine to make turning the
steering wheel easier. Some
very modern systems use small
electric motors for this task.
Suspension system The main
reasons for the suspension
system are as follows:
• Absorb road surface
faults (shocks) to give a
comfortable ride
• Keep the tyres in contact
with the road surface
• Resist braking and
33
steering forces
• Allow for different loads
of passengers and luggage
A single trailing arm with coil
springs and damper on the rear
and strut with a coil spring and
built in damper on the front
are shown here. Many
variations of design are used
but the principle is the same.
Tyres also absorb road shock
and play a very important part
in road holding. Most of the
remaining shocks and
vibrations are absorbed by
springs in the drivers and
passengers seats.
Draw the suspension spring
before and after the wheel
hits a bump…
Electrical system The electrical system covers many aspects
such as lighting, wipers and instrumentation. A key aspect is the
production of a spark to ignite the fuel (unless the engine is
diesel of course). An alternator, driven by the engine, produces
electricity to run the electrical systems and charge theAUTOMOTIVE TECHNICIAN TRAINING – © TOM DENTON
36
squashed. Take care to avoid damage to other components of
the vehicle.
AUTOMOTIVE TECHNICIAN TRAINING – © TOM DENTON
37
Oily Rags and Contaminated Clothing Never keep oily rags in
overall, or other pockets, and change out of oil-contaminated
clothing as soon as reasonably possible.
Disposing of Used Engine Oils Dispose of used engine oil to a
licensed waste-disposal company, or to an approved collection
point. Never pour any oils into a drain or onto the ground. Oils
are often carcinogenic and can cause cancers.
Grade and Type of Oil In consideration of the ‘duty of care’ to
other people’s property, always be careful to use the correct
grade and type of oil for oil changes.
Pressure-Relief Valves Pressure-relief valves are controlled by
spring tension. Always wear safety goggles when removing and
replacing these because they can, in some circumstances, fly out
with their own spring force.
Oxyacetylene When removing parts of the exhaust system, it
may be necessary to use an oxyacetylene flame to heat up pipes.
This is to free them so they can be separated. Always follow
standard safety precautions for the use of the equipment. Be
very careful that the flame is directed ONLY onto the exhaust-
pipe joint, and always pointing away from fuel pipes and the
vehicle floor. Use protective screens where flammable
substances are in the area of the flame, or consider another
method if the fire risk is too high.
Avoid Fires The main safety precautions to avoid fires where
fuel or vapour is likely to be around, is to disconnect the vehicle
37
Oily Rags and Contaminated Clothing Never keep oily rags in
overall, or other pockets, and change out of oil-contaminated
clothing as soon as reasonably possible.
Disposing of Used Engine Oils Dispose of used engine oil to a
licensed waste-disposal company, or to an approved collection
point. Never pour any oils into a drain or onto the ground. Oils
are often carcinogenic and can cause cancers.
Grade and Type of Oil In consideration of the ‘duty of care’ to
other people’s property, always be careful to use the correct
grade and type of oil for oil changes.
Pressure-Relief Valves Pressure-relief valves are controlled by
spring tension. Always wear safety goggles when removing and
replacing these because they can, in some circumstances, fly out
with their own spring force.
Oxyacetylene When removing parts of the exhaust system, it
may be necessary to use an oxyacetylene flame to heat up pipes.
This is to free them so they can be separated. Always follow
standard safety precautions for the use of the equipment. Be
very careful that the flame is directed ONLY onto the exhaust-
pipe joint, and always pointing away from fuel pipes and the
vehicle floor. Use protective screens where flammable
substances are in the area of the flame, or consider another
method if the fire risk is too high.
Avoid Fires The main safety precautions to avoid fires where
fuel or vapour is likely to be around, is to disconnect the vehicle
38
battery whenever it is not required for the current task. Mark
off with warning signs a ‘no naked flames’ work area. Obtain, and
keep close by, a suitable fire extinguisher such as CO2 . When
checking cylinder compressions or any similar task disable the
ignition system.
Check which extinguishers are safe to use on fuel fires
Draining Fuel Never drain fuel into an open container such as a
bowl, oil drain tray or cans where there is a risk of spillage from
overfilling. Always use a pumped, sealed and earthed or
grounded tank that is specially constructed for the job.when the pressure is
released. In the case of petrol, the risk is from a spray when a
pipe or hose is loosened or punctured. The petrol spray could
cause a fire if ignited and a personal injury if sprayed into the
eyes. Involuntary movement into a rotating component is also
possible. Always wear safety goggles when working with
pressurised fuel lines.
Fuel is under pressure
Releasing Fuel Pressure Most petrol fuel injection systems
have a method for releasing the fuel pressure. In some cases, a
pressure release valve is fitted to the fuel rail. In others, it
may be necessary to disable the fuel pump by removing a fuse or
relay and running the engine until it stalls. Some systems may
need a pipe union or joint to be gently eased to release the
pressure. In all cases, follow the manufacturer’s instructions.
Fuel pressure valve
40
Compressed Air It is sometimes required to use an air line to
clean components or fuel pipelines. Take care with compressed
air. It must not be directed towards the skin. Always wear
safety goggles when using an air line.AUTOMOTIVE TECHNICIAN TRAINING – © TOM DENTON
41
Test Instruments Observe all standard procedures for the use
of electrical instruments. Always observe the correct polarity,
range, and connections.
High Voltages Ignition circuits use pulses of electrical energy
in excess of 10,000 volts. These are created in the ignition coil,
and conducted through the coil and spark-plug wires. Although
shocks from ignition systems are rarely fatal, the reaction to
the shock may cause serious injury, such as the involuntary
movement of hands and arms, or whole body movements, into
hazardous areas like running engines.
Running Engines Whenever carrying out tests on running
engines, an awareness of rotating components must be
maintaiAUTOMOTIVE TECHNICIAN TRAINING – © TOM DENTON
42
carried out. Note that it may be necessary to use a ‘keeper’ to
keep memory circuits alive if the battery is disconnected.
Working Below Vehicles There are a number of hazards to
avoid when working below vehicles. One is the risk of hitting
yAUTOMOTIVE TECHNICIAN TRAINING – © TOM DENTON
43
ignition. Do not allow high-voltage secondary-circuit sparks of
more than 5 to 6mm to occur during test procedures. This can
cause damage to electronic components. It is recommended that
electronic modules be removed if arc welding is required on the
vehicle.
Battery Polarity When fitting and
connecting a battery it is important to
observe the correct polarity. This is
necessary to reduce the risk ofAUTOMOTIVE TECHNICIAN TRAINING – © TOM DENTON
44
lifting equipment of the cross grip type, take care that the
battery case is not fractured.
Battery Acid Mixing battery acid is not now a common task.
However, if acid is to be mixed, all safety rules must be
followed. This operation should only be carried out in a place
specially prepared and AUTOMOTIVE TECHNICIAN TRAINING – © TOM DENTON
44
liftinAUTOMOTIVE TECHNICIAN TRAINING – © TOM DENTON
47
excess of 100 mph! Note how important it is to ensure all
driveline components are in good order.
Transmission Wind Up On four-wheel drive vehicles, it is
possible for the trar the purpose; leather or fabric
gloves arAUTOMOTIVE TECHNICIAN TRAINING – © TOM DENTON
49
MAINTENANCE, REGULATIONS AND INFORMATION
REASONS FOR MAINTENANCE AND INSPECTIONS
Vehicle Protection Clearly, it is important to keep a customer’s
vehicle in a clean condition. To do this there are a number of
methods as outlined here:
• Seat covers to keep the seats cleanAUTOMOTIVE TECHNICIAN TRAINING – © TOM DENTON
50
Inspections The main purpose of regular inspection is to check
for the following:
• Malfunction of systems and components
• Damage and corrosion to structural and support regions
• Leaks
• Water ingress
• Component and system wear and security
Inspections are usually:
• Aural – listening for problems
• Visual – looking for problems
• Functional assessment – checking that things work!
Types of Inspection The main types of inspection you may
have to carry out are:
• Pre-work
• Post-work
• Pre-delivery inspection (PDI)
• Used vehicle inspection
• Special inspectishould be used and
careful records of your findings should be kept.
Timescales Working to timescales, or reporting to a supervisor
that timescales cannot be met, is essential for two reasons.
Firstly, when a cuAUTOMOTIVE TECHNICIAN TRAINING – © TOM DENTON
52
INFORMATION SOURCES, RECORDING AND REGULATIONS
Information Sources The main sources of information are:
• technical manuals
• technical bulletins
• servicing schedules
• job card instructions
• inspection records
• check lists
Documentation and Records It is essential that proper
docume both keep customers informed and so the
invoice caAUTOMOTIVE Tlf along. Adjusting
screws on some types of die allow them to be closed or opened
slightly to allow small variations in size. Split dies can be
adjusted by screws in the die holder. The action used to cut the
thread is similar to that used when tapping.
Die nuts have no split for resizing and are made from a
hexagonal bar so that a wrench or spanner can be used to turn
them. Die nuts are used to clean up existing threads and should
not be used to cut neAUTOMOTIVE TECHNICIAN TRAINING – © TOM DENTON
56 eighteen to thirty-two
teeth per inch (TPI) for a hand hacksaw blade. The blade
chosen is based on the thickness of the material being cut, with
a minimum of three teeth in the material. As hacksaw teeth are
so small, they are set in a wave so that the resulting cut is wider
than the blade to prevent jamming. Hacksaw blades are often
brittle so care need
Tool kit Bench Drilleeping the drill
perpendicular to the work surface. This walking or slipping
across the surface can be prevented by making a centring mark
before drilling. This is most often done by centre punching. If a
large hole is needed, t
FILING
Filing is the processs, shapes, cuts, and tooth
configurations. The most common cross-sections of a file are:
flat, round, half-round, triangular and square. The cut of the
file refers to how fine its teeth are. They are described, from
roughest to smoothest, as: rough, middle, bastard, second cut,
smooth, and dead smooth. The picture shows three common file
cuts. Most files have teeth on all faces, but some flat files have
teeth only on one face or edge, so that the file can work against
another edge witho of removing material when manufacturing
something; it is used mostly for finishing operations. Filing can
be used on a wide range of materials as a finishing process.
Emery paper may be considered as a filing tool.
Hand filling (Source: South Thames College)
Files have forward-facing cutting teeth that cut best when
pushed over the workpiece. A process known as draw filing
involves turning the file sideways and pushing or pulling it across
the work. This catches the teeth of the file sideways and
results in a very fine shavECHNICIAN TRAINING – © TOM DENTON
55
Repairs using lathe (Source: Wikimedia)
Machinists usually work to very small tolerances, ±0.1 mm for
example and deal with all aspects of shaping and cutting. The
operations most often carried out by machinists are milling,
drilling, turning, and grinding. To carry out fitting or machining
operations you should be familiar with:
• Measuring tools such as a micrometer
• Hand tools as found in a standard tool kit
• Machine tools such as a bench drill
• Work holders for example a vice
• Tool holders such as the chuck of a drill
• Cutting n be prepared correctly. Further, it is important to
protect yourself in the event of a claim being made against you
or your company.
Look back over the previous section and write out a list of
the key bntation is used and that records are kept of the work
carried out. For example:
• job cards
• stores and material recordsr suspension was
modified it may become unsafe and not conform to the
law.
• VOSA regulations – the main one of these being the
annual MOT test requirements. VOSA stands for: Vehicle
and Operator Services Agency
• Highway code – which all drivers must follow and forms
part of the driving test.
Summary To be able to carry out your work correctly and to
the required standard it is important to use up to date and
relevant information. Keep proper records of work done and
parts used. This is to both
• manufacturers’ warranty systems
These are needed to ensure the customer’s bill is accurate and
also so that information is kept on file in case future work is
required or warranty claims are made.
Recording Results of Diagnostic Tests Results of diagnostic
tests will be recorded in a number of different ways. The
actual method will depend on what test equipment was used.
Some equipment will produce a printout for example. However,
results of all other tests should be recorded on the job card.
In some cases this may be done electronically but the principle
is the same. Remember to make sure that the records are
clear andstomer books a car in for work to be done
they expect it to be ready at the agreed time. Clearly if this
time can’t be me the customer needs to be informed.
Secondly, in order to make the running of a workshop efficient
and profitable, a technician will have jobs allocated that will
take a certain amount of time to complete. If for any reason
the allotted time can’t be met then action will need to be taken
by the workshop manager of supervisor.
Summary There are moreon (maybe after an accident for example)
A pre-work inspection is used to find out what work needs to
be carried out on a vehicle. Post-work inspections are done to
make sure the repairs have been carried out correctly and
then no other faults have been introduced.
A PDI is carried out on all new vehicles to check certain safety
items and to, for example, remove any transport packaging
such as suspension locks or similar. A used vehicle inspection is
done to determine the
• Floor mats to protect the carpets from dirt
• Steering wheel covers to keep greasy hand prints off the
wheel
• Wing covers to keep the paintwork clean and to prevent
damage.
Maintenance The purpose of routine maintenance is simple; it
is to keep the vehicle in a good working order and in a safe
condition.
Manufacturers specify intervals and set tasks that should be
carried out at these tie NOT suitable. If refrigerant is exposed to naked
flames or hoAUTOMOTIVE TECHNICIAN TRAINING – © TOM DENTON
48
times. Use gloves designed for the purpose; leather or fabric
gloves are NOT suitable. If refrigerant is exposed to naked
flames or hot surfaces, it produces toxic gases. Always ensure
adequate ventilation when working on air conditioning systems.
Air conditioning unit and equipment
Pressurised Cooling Systems If work has to be carried out on
the vehicle heater or the cooling system, there is a risk of
scalding. The coolant is run at a pressure higher than
atmospheric. If the cap is removed when hot, the coolant can
boil instantly ejecting boilint surfaces, it produces toxic gases. Always ensure
adequate ventilation when working on air conditioning systems.
Air conditioning unit and equipment
Pressurised Cooling Systems If work has to be carried out on
the vehicle heater or the cooling system, there is a risk of
scalding. The coolant nsmission to ‘wind up’ when the front and
rear axles are locked together. This is because the two axles
may run at slightly different speeds. When on rough ground it is
not a problem because the bouncing and movement allows the
tyres to slip. On hard surfaces however, a twist or ‘wind up’ of
the components such as driveshafts occurs. When the vehicle is
jacked up, the transmission can unwind suddenly causing serious
injury. This does not occur on a vehicle with an unlocked centre
differential or a viscous drive.
Springs Under Compression When coil springs are removed
from a suspension strut, they should be held using a special tool.
If the fixings are removed without compressing the spring, it
may relg equipment of the cross grip type, take care that the
battery case is not fractured.
Battery Acid Mixing battery acid is not now a common task.
However, if acid is to be mixed, all safety rules must be
followed. This operation should only be carried out in a place
specially prepared and designated for the purpose. Safety-wear
includes a PVC apron and gloves, and a chemicals-rated face
visor. One rule abover skin. Gloves, goggles,
breathing masks, hats and strong footwear may also be
necessary. Refer to local regulations for any special
requirements.
Skin Contact When servicing vehicle systems avoid skin contact
with new and used engine oils. Use barrier cream or non-porous
gloves. Be careful with hot oil, particularly when carrying out oil
draining operations. Never keep oily rags in overall or other
pockets and change out of all others must be remembered, and that
is that acid is added to the distilled water. Water added to acid
will boil on contact causing an explosive reaction.
Lifting Heavy ObAUTOMOTIVE TECHNICIAN TRAINING – © TOM DENTON
45
high concentration of gas, and the risk of a spark, being brought
together near the battery. Always ensure that the battery
charging area is a no smoking area and that notices are posted
to ensure that this rule is observed.
Disposal of Batteries The disposal of batteries and battery
acid is subject to local environmental regulations. If procedures
are not in place in your workshop, seek advice from your local
environmental agency. Never dispose of batteries with normal
waste. Many areas have a collection site for hazardous materials
and batteries can normally be takjects Batteries should be treated as heavy
objects when being lifted. Add to this that there are special
conditions attached because of the acid content. It is,
therefore, important to plan the lift procedure beforehand and
to have the correct equipment available if required. Many
modern vehicle batteries that are more than 20 kg (40 lbs.) in
weight, are fitted with lifting ropes and handles. Check that
these are in good condition before lifting.
Flammable Gas The gas that is given off from a battery during
charging is a mixture of hydrogen and oxygen. This is a highly
flammable and potentialldesignated for the purpose. Safety-wear
includes a PVC apron and gloves, and a chemicals-rated face
visor. One rule above all others must be remembered, and that
is that acid is added to the distilled water. Water added to acid
will boil on contact causing an explosive reaction.
Lifting Heavy Objects Batteries should be treated as heavy
objects when being lifted. Add to this that there are special
conditions attached because of the acid content. It is,
therefore, important to plan the lift procedure beforehand and
to have the correct equipment available if required. Many
modern vehicle batte
damage to the electrical and
electronic systems on the vehicle. A
memory saver device may be needed
for some vehicles. Check with the
vehicle manufacturer’s data before
disconnecting the battery.
Battery polarity Memory saver
Battery Connection When connecting and disconnecting the
battery leads ensuour head, which can obviously cause injury. Another risk is the
possibility of getting rust and dirt in the eyes. Avoid these
problems by wearing a bump cap and goggles, whenever working
below vehicles. The vehicle must always be supported safely
before working underneath or alongside it.
Car on a ramp
Overheated Coils Contact-breaker ignition coils can become
very hot if the ignition is left on without the engine running.
However, most electronic systems require the engine to be
started to trigger the switching of the primary circuit. These
systems will not overheat.
DIS coil
Arcing and Sparking! For all electronic-ignition systems, avoid
causing arcing when disconnecting terminals. This is achieved by
disconnecting the battery earth lened. This is particularly important when using a
stroboscopic-timing light because it can give the impression
that the engine is stationary. Exhaust extraction should always
be used.
Cooling Fans Keep fingers clear of electrically operated cooling
fans because they are likely to start without warning during
running-engine tests.
Short Circuits As with all electrical work, there is a risk from
short circuits to ground causing fires and very hot strands of
wire. Follow standard procedures with the removal and
reconnection of the batte
Diesel Injection Systems Diesel injection systems work at very
high pressures. Particular care must be exercised to ensure
that diesel fuel is not injected through the skin and into the
body. This risk is greatest when carrying out tests on injectors.
Always follow correct safety and operational procedures for
these tests. Wear a full-face
Fuel drainer
Skin Care All fuels and oils are harmful to skin and internal
organs. The range of hazards is from drying out of the skin to
dermatitis and cancers. Avoid prolonged or frequent contact
with fuels and oils. Use a barrier cream or suitable gloves and
wash after any skin contact as soon as reasonably possible.
Replace skin oils with a lanolin cream. Never keep contaminated
cloths in pockets.
Sharp Objects Engine components are made from hard
materials by various manufacturing methods that can produce
very sharp corners. Minor cuts are common but more serious
cuts can occur. Always treat cuts and grazes immediately. Avoid
close work by selecting tools that bring hands away from sharp
points. Socket extensions are suitable for this.
Protective Clothing During cleaning operations, chemicals or hot
water or steam are used and personal protective clothing and
procedures that are described in the manufacturer's manuals or
data sheets must be followed.
Engine Oils Particular points t
battery.
34
Summary Layouts of a vehicle vary as do body styles and
shapes. However, the main systems of a light vehicle are very
similar. These are the:
• Power train
• Braking system
• Steering system
• Suspension system
• Electrical system
These systems are covered in more detail in other sections of
‘Automotive Technician Training’
Look back
drive shafts must be
possible by a unit called
the differential. This is
needed because when the
vehicle is cornering the
road wheels turn at
different speeds.
Drive shafts The two drive
shafts each have two constant
velocity (CV) joints. Th
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