Page 66 - Automobile Mechanical and Electrical Systems Automotive Technology Vehicle Maintenance and Repair (Vehicle Maintenance Repr Nv2) by Tom Denton

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Figure 1.71 Corrosion on an exhaust joint

Table 1.23 Terms used to describe materials
Property Explanation
Hardness The ability to withstand indentation (marking)

Softness Can be easily indented
Toughness The ability to resist fracture
Brittleness Breaks or shatters under shock loads (impact)
Ductility Plastic (deforms and stays that way) under tension or stretching

Malleability Plastic under compression (squeezing)
Plasticity The ability to retain a deformation after a load is removed
Elasticity The ability to return to its original shape when a deforming load is
removed

Strength The ability to withstand a load without breaking

combines with oxygen and water to form a brown deposit known as rust. Higher
temperatures make this reaction work more quickly. Salty road and air conditions
make car bodies rust more quickly.
Material properties are listed in Table 1.23 . Some materials other than metals
corrode or perish over a period of time, for example rubber-based materials.
Plastics have a great advantage because some appear to last for ever!

1.5 Tools and equipment

1.5.1 Hand tools

Using hand tools is something you will learn by experience, but an important fi rst
step is to understand the purpose of the common types ( Fig. 1.72 ). This section
therefore starts by listing some of the more popular tools, with examples of their
use, and ends with some general advice and instructions.
Practise until you understand the use and purpose of the tools listed in Table
1.24 when working on vehicles.