ASVAB Automotive Information Practice Test 448482

Questions 5
Topics Camshaft, Ignition Timing, Transfer Case, Water Jacket, Wheel Hub

Study Guide

Camshaft

The camshaft is linked to the crankshaft through a timing belt and regulates the opening and closing of the intake and exhaust valves in each cylinder in time with the motion of the piston. An engine designated OverHead Camshaft (OHC) locates the camshaft in the cylinder head. An engine with Double OverHead Camshaft (DOHC) has two camshafts, one to regulate the intake valves and one to regulate the exhaust valves.

Ignition Timing

Ignition timing defines the point in time at the end of the compression stroke that the spark plug fires. Measured in number of degrees before top dead center (BTDC), the exact point that the spark plugs initiate combustion varies depending on the speed of the engine. The timing is advanced (the spark plugs fire a few more degrees BTDC) when the engine is running faster and retarded when it's running slower.

Transfer Case

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

Water Jacket

A water jacket is a coolant-filled casing that allows heat transfer from the engine block and cylinder heads to the liquid coolant.

Wheel Hub

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.