ASVAB Automotive Information Practice Test 576907 Results

Your Results Global Average
Questions 5 5
Correct 0 2.90
Score 0% 58%

Review

1

What is the pimary advantage of using power brakes on a vehicle?

62% Answer Correctly

requires less brake fluid to operate the braking system

utilizes battery power to assist in braking

allows the use of antilock brakes

provides higher hydraulic pressure in the braking system


Solution

Power brakes multiply the force a driver applies to the brake pedal using a vacuum booster connected to the engine intake manifold. This provides for much higher hydraulic pressure in the braking system than could be generated by the driver alone. Antilock brakes (ABS) use speed sensors and adjust the brake pressure at each wheel to prevent skidding and allow the driver more steering control in slippery conditions.


2

Which of the following is the result of combustion being initiated by a source other than the spark plug?

51% Answer Correctly

ignition

pre-ignition

detonation

pre-combustion


Solution

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.


3

Piston rings are responsible for which of the following?

50% Answer Correctly

connecting the piston to the camshaft

regulating oil distribution inside the cylinder

connecting the piston to the spark plug

containing combustion


Solution

Cylinders act as a guide for the pistons that translate the heat energy of combustion into the mechanical energy necessary to move a vehicle. Piston rings seal the piston to the cylinder to contain combustion gases and also regulate the oil distribution between the piston and cylinder wall. A cylinder head closes in the top of the cylinder forming the combustion chamber which is sealed by a head gasket (head). The head provides space for air and fuel intake valves, exhaust valves, and mounts for spark plugs and fuel injectors.


4

The spark plugs fire a few extra degrees before top dead center when the engine is running faster. In this case the engine's timing is:

62% Answer Correctly

synchronous

retarded

asynchronous

advanced


Solution

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.


5

The intake ports on the cylinder heads is fed outside air via the:

67% Answer Correctly

intake air pump

intake control module

intake manifold

intake pressure regulator


Solution

The intake manifold distributes outside air to the intake ports on the cylinder heads. The intake air filter removes any airborne contaminants before the air enters the engine.