During the compression stroke, both intake and exhaust valves are closed as the piston begins moving back up from the bottom of the cylinder (bottom dead center or BDC). This compresses the air-fuel mixture in the combustion chamber which also makes it hotter.

The lighting system consists of interior lights, instrument panel lighting, headlights, and taillights. Like household electrical circuits, the vehicle's lighting system is protected from current spikes by fuses and circuit breakers.

Suspension springs are made with wide gap coils of rigid steel cable and both hold the vehicle chassis up off the ground and absorb energy from wheel movement making for a smoother ride.

The transfer case splits engine power between the front and rear axles of four-wheel drive vehicles.

The wheel hub is the mounting point for the wheel and tire assembly. The wheel hub can rotate while being held stable by the steering knuckle which applies the motion of the control arms to the wheels.