Vehicle Technology, Vehicle Dynamics and Maintenance
What the exam tests
You must explain how a car works well enough to diagnose a learner's problem and to justify a safety decision. The exam links technology to dynamics: why a worn damper lengthens braking, why a cold tyre reads low, why ABS is not a licence to brake late.
Technology you must explain
- Drivetrain: engine, clutch, gearbox, differential; automatic and dual-clutch gearboxes differ in creep and launch behaviour.
- Brakes: hydraulic circuit, disc and drum, ABS, electronic brake-force distribution, ESP and brake assist.
- Steering and suspension: rack-and-pinion, electric power assistance, MacPherson struts, multi-link axles, dampers.
- Tyres: legal minimum tread 1.6 mm, pressure measured cold, load and speed indices, DOT age, winter and all-season compounds.
- Fluids and exhaust: engine oil, coolant, hygroscopic brake fluid (typically changed every two years), diesel particulate filter and AdBlue/SCR.
- Electric and hybrid vehicles: high-voltage system, orange cables, never touch damaged components; the vehicle is silent at low speed.
Dynamics in teaching terms
- Weight transfers under acceleration, braking and cornering; the traction circle shows that a tyre cannot give maximum braking and maximum cornering at once.
- Understeer means the front runs wide; oversteer means the rear breaks away. Aquaplaning removes contact gradually, not suddenly.
- ABS preserves steering but can lengthen stopping distance on gravel or fresh snow. ESP intervenes late and cannot repeal physics.
- Braking distance rises with the square of speed; reaction distance rises linearly.
Worked example
At 50 km/h a driver travels 13.9 m per second. With one second reaction time and a friction coefficient of about 0.8, the total stopping distance is roughly 14 m + 12 m = 26 m. At 100 km/h the reaction distance doubles to 28 m and the braking distance quadruples to about 49 m, giving roughly 77 m. Doubling speed nearly triples the total distance, which is why the safety margin must grow faster than the speedometer.
Traps that cost marks
- Calling 1.6 mm a safe tread depth; it is only the legal floor.
- Claiming ABS always shortens braking distance.
- Checking tyre pressure after a fast drive and accepting the hot reading.
- Ignoring dampers and springs when a learner reports instability under braking.