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Cameroon Heavy-Vehicle Theory study materials
Cameroon Heavy-Vehicle Theory study resources

Cameroon Heavy-Vehicle Theory: Heavy-Vehicle Mechanical Knowledge and Pre-Trip Inspection

Cameroon Heavy-Vehicle Theory · Work through your exam, one topic at a time.

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Heavy-Vehicle Mechanical Knowledge and Pre-Trip Inspection

Domain 3, Heavy-Vehicle Mechanical Knowledge and Pre-Trip Inspection, tests the daily inspection routine and the systems that most often cause truck crashes: brakes, tyres, steering, coupling, lights and fluid leaks. The exam expects a logical walk-around and the ability to reject a vehicle that is not roadworthy.

Core rules

  • Start with documents and a walk-around: check for leaks under the engine, gearbox and hubs; inspect tyre tread, sidewalls and dual spacing; confirm wheel nuts and valve caps; check lights, reflectors, mirrors, windscreen and wipers.
  • Under the bonnet, check engine oil, coolant, brake fluid where fitted, power-steering fluid, battery security and belt condition. Do not open a hot cooling system.
  • Air-brake checks: build pressure to the governed range, switch off and listen for leaks; confirm the low-pressure warning operates; test the service brake and parking brake. A steady pressure loss or a brake that will not hold must be repaired before departure.
  • Check the coupling: fifth-wheel jaws closed and locked, kingpin seated, safety catch engaged, air lines and electrical lead secure, landing legs raised, trailer brake operational.
  • Check load security, tyre pressure when cold, and the spare wheel and tools. Confirm the ABS warning lamp extinguishes after the self-test; a lamp that stays on means a fault.

Worked example

After building air pressure to 8 bar, a driver switches off the engine. The gauge falls to 6 bar in two minutes and the low-pressure buzzer sounds late. The driver should not depart. The leak rate is excessive and the warning test is unsatisfactory; the likely causes include a leaking chamber, hose, valve or compressor governor. The correct action is to isolate the vehicle, report the defect and have a qualified mechanic repair it. A road test cannot substitute for a leak test.

Traps

  • Inspecting only the visible side of the truck and skipping the far-side duals.
  • Assuming ABS shortens stopping distance on gravel or mud.
  • Forgetting to check the trailer parking brake and the breakaway system.
  • Treating a low tyre as acceptable because it “looks soft only at the bottom”.