How A Car Works

From The Road Up is a series written by a vehicle engineer, working through each major system on a car in turn. No jargon for its own sake, and no assumption that you already know what a camshaft is. Read it in order or dip into the part you need.

• 1. Vehicle Structure

  Monocoque versus separate chassis, and how crumple zones absorb crash energy.

• 2. The Petrol Engine

  The four stroke cycle, valve timing, and why more cylinders run smoother.

• 3. The Diesel Engine

  Compression ignition: no spark, 175 bar injection, and 600°C from pressure alone.

• 4. Engine Fuel Control

  Pumps, regulators, injectors, and how the ECU decides injection duration.

• 5. Ignition

  Turning 12 volts into 40,000, and why timing advances and retards.

• 6. The Clutch

  Flywheel, driven plate, diaphragm spring, and why the friction lining must slip.

• 7. The Gearbox

  Gear ratios explained on a bicycle, and why a truck needs sixteen of them.

• 8. The Final Drive

  Driveshafts, propshafts and the differential that lets a car turn a corner.

• 9. Braking

  Hydraulics, friction, and why the dual circuit and a mechanical handbrake exist.

• 10. Suspension

  Steel, rubber and fluid springing — and why the damper matters as much.

• 11. Steering

  Feedback through the wheel, collapsible shafts, and what uneven tyre wear means.

• 12. Tyres

  The first stage of the suspension, and five litres of water cleared per second.

• 13. Basic Electrics

  Wire sizing, fuse ratings, and why some circuits need resistance on purpose.

• 14. Starter Motors

  The solenoid's two jobs, and the 500 amps a cold morning can demand.

Keeping it running

The companion series, Keep It Going, covers what servicing actually involves — weekly checks through to a full major service.