Trade-related Mathematics, Science and Drawing
Mathematics
Know unit conversions (1 inch = 25.4 mm, 1 litre = 1000 cm3, 1 kW = 1.36 hp), percentages, ratios, averages and simple geometry. Circle area = pi r2; circumference = pi d; cylinder volume = pi r2 h. Ohm's law and power formulas appear frequently. Gear and pulley ratios use driven / driving.
Science
Understand friction, pressure, heat transfer, expansion and basic chemistry of combustion. Metals expand when heated; this explains clearances and thermostat operation. Pressure = force / area. Energy cannot be created or destroyed, only converted.
Drawing
Read orthographic projections (first-angle and third-angle), section views, dimensioning and tolerances. Know line types: continuous thick for outlines, dashed for hidden detail, chain for centre lines. Interpret surface finish symbols and limits and fits (clearance, interference, transition).
Worked example: a cylinder of bore 80 mm and stroke 90 mm has volume pi/4 x 8^2 x 9 = 452 cm3. If the clearance volume is 50 cm3, compression ratio = (452 + 50) / 50 = 10.04:1.
Traps: mixing radius and diameter, forgetting unit conversion, and misreading hidden lines. Rule of thumb: write units at every step and check the answer's magnitude for plausibility.
Industrial Safety
Workplace hazards
Industrial safety covers machinery guarding, electrical safety, manual handling, hazardous substances, noise, vibration and confined spaces. Guards and interlocks prevent access to moving parts; never bypass them. Lockout/tagout isolates energy before maintenance. Safety data sheets (SDS) describe chemical hazards, handling and first aid.
Fire and emergency
Know fire classes and extinguisher selection, evacuation routes, assembly points and the roles of fire wardens. Emergency stops must be accessible and tested. First aid kits and eye-wash stations must be stocked and reachable.
Ergonomics and environment
Correct lifting technique, workstation height and tool design reduce strain. Ventilation controls fumes and dust. Noise above about 85 dB requires hearing protection and monitoring.
Traps: assuming PPE replaces guarding, ignoring isolation before clearing jams, and using the wrong extinguisher. Rule of thumb: if a machine can be started while you are inside it, the isolation is inadequate.
Worked example: a workshop with a noise reading of 92 dB exceeds the 85 dB action level, so hearing protection and noise reduction measures are required.
Environment and Professional Practice
Environmental responsibility
Garages generate waste oil, filters, batteries, tyres, solvents and refrigerant gases. Each has a regulated disposal route: waste oil to licensed collectors, batteries to recyclers, refrigerants recovered and never vented. Spill kits and bunded storage prevent soil and water contamination. Segregate waste at source and keep manifests.
Professional practice
Act with honesty, competence and respect for the customer. Explain faults and costs clearly, obtain authorisation before extra work, protect customer property and data, and keep accurate records. Maintain confidentiality and avoid conflicts of interest. Follow manufacturer procedures and use genuine or approved parts where specified.
Sustainability
Efficient driving, correct tyre pressures, timely servicing and proper recycling reduce emissions and cost. Alternative fuels and electric vehicles bring new hazards, including high-voltage systems that require trained isolation.
Traps: pouring used oil down drains, venting refrigerant, and promising repairs beyond your competence. Rule of thumb: if you would not want it done to your own vehicle, do not do it to a customer's.
Worked example: a shop producing 200 litres of waste oil per month must store it in a labelled, bunded container and hand it to a licensed collector with documentation.