Automobile Workshop Practice and Tools
This domain tests the selection, care and correct use of hand tools, measuring tools and workshop equipment.
Measuring tools
- Vernier caliper: measures outside, inside and depth; common least count 0.02 mm.
- Micrometer: measures outside dimensions; common least count 0.01 mm.
- Feeler gauge: measures gaps such as valve clearance.
- Dial gauge: measures runout and backlash.
- Torque wrench: tightens to a specified torque in Nm.
Hand and bench tools
- Use the correct size spanner or socket; an adjustable wrench can round nuts.
- Files cut on the forward stroke; hacksaws cut on the forward stroke with light pressure.
- A bench vice holds work; a tap cuts internal threads and a die cuts external threads.
- Support the vehicle on stands and use the correct lifting points.
Worked example
A vernier caliper has a least count of 0.02 mm. The main scale reads 12 mm and the 13th vernier division coincides with a main-scale line. Reading = 12 + (13 × 0.02) = 12 + 0.26 = 12.26 mm. The reasoning is to add the vernier fraction to the main-scale reading.
Traps
- Reading a vernier from the wrong zero or ignoring parallax.
- Using a micrometer without checking zero error.
- Using an adjustable wrench on a tight, precise nut.
- Using a torque wrench as a breaker bar.
- Cutting with a hacksaw on the return stroke.