ASVAB Automotive Information Practice Test 362578

Questions 5
Topics Combustion, Firing Order, Independent Suspension, Water Pump, Wheel Hub

Study Guide

Combustion

Normal combustion in an engine is initiated by a spark plug and results in the complete burning of the air-fuel mixture. If combustion is initiated by a source other than the spark plug, by a hot spot in the cylinder or combustion chamber for example, pre-ignition results. Detonation results if the air-fuel mixture explodes instead of burning. Detonation can cause extremes in pressure in the combustion chamber leading to engine damage.

Firing Order

The stroke cycle of an engine is governed by the crankshaft which serves to regulate the firing order of the cylinders. All cylinders are not on the same stroke at the same time and correct firing order is important to balance engine operation and minimize vibrations. A common firing order for four-cylinder engines is 1-3-4-2 which indicates that cylinders 1 and 3 fire (power stroke)together and cylinders 4 and 2 fire together.

Independent Suspension

Most modern cars use an independent suspension system on the front wheels. This setup allows each of the wheels on an axle to move independently in response to road level variations. Independent suspension offers much better handling and stability when compared to a rigid axle suspension at the cost of being structurally weaker and more costly to maintain.

Water Pump

The water pump is driven by a belt connected to the crankshaft and ensures that coolant moves through the engine and radiator.

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.