ASVAB PRACTICE TEST A

Answers and Explanations

Part 7: Automotive and Shop Information (AS)

1. D
   While a miter box might be used with a backsaw to make even cuts in wood at specific angles, by itself, it is not capable of shaping wood. All of the other choices are tools capable of making cuts or smoothing edges on wood.
2. B
   Of all the aspects of vehicle operation, two that are a high priority for most drivers are ride comfort and handling. The suspension system, choice (B), is responsible for the ride quality of the vehicle.
3. D
   The cut or slot left by a saw in a piece of wood is also known as a kerf.
4. D
   The transfer case is located between the transmission and the drive axles on a four-wheel drive vehicle and is the piece that splits the engine’s power between the front- and rear-drive axles.
5. B
   This is a crosscut saw. It is designed to, as its name suggests, cut across the grain of the wood. Crosscut saw teeth are unique in that they cut like a knife, in contrast to a ripsaw, which is made to cut with the grain of wood.
6. C
   This image depicts the compression stroke, which is the second stroke in the four-stroke cycle.
7. A
   Fractional measurement fasteners (measured in fractions of inches) use threads that are identified by the number of threads per inch.
8. D
   To loosen tight fasteners, it is good to use a box-end wrench. Choice (B) depicts a combination wrench, which has an open end wrench on one side and a box end on the other. Choice (C) shows a wrench with box ends on both sides. Therefore, both (B) and (C) are suitable for loosening tight fasteners; choice (D) is the correct answer. The box end wraps completely around the head of a bolt, and therefore makes greater surface contact.
9. A
   Of the answer choices given, only (A), coil spring, is not a part associated with the steering system. Coil springs are what aid the wheels in moving up and down while the vehicle chassis stays steady. The other pieces listed—steering knuckle, tie rod end, and idler arm—are all parts of the steering system.
10. C
    The camshaft, indicated in the diagram by the number 3, is responsible for the opening and closing of the engine’s intake and exhaust valves. The camshaft turns at one-half the speed of the engine’s crankshaft.
11. D
    In fuel-injected engines, the electric fuel pump is located in the vehicle’s fuel tank and is what supplies fuel under pressure to the fuel injectors.
12. B
    The two basic thread classifications—Unified National Coarse (UNC), and Unified National Fine (UNF)—have different numbers of threads per inch. A UNC or coarse thread would have relatively few threads per inch, where a UNF or fine thread would have a larger number of threads per inch.
13. C
    Power brake systems use both the engine intake manifold vacuum and fluid pressure from the power steering system to increase pressure. Engine intake manifold vacuum is utilized to generate greater force on the master cylinder, so higher hydraulic pressures can be generated in the brake system. Some brake booster systems use fluid pressure from the power steering system to increase braking power.
14. D
    The primary is the low-voltage part of the -system and contains a battery, an ignition switch, a primary coil winding, an ignition module, a reluctor and pickup coil, and a -distributor. A rotor is not a part of the ignition primary system.
15. A
    Stoichiometric is the ideal ratio of air to fuel in the engine and it is the responsibility of the engine’s fuel system to maintain this balance.
16. D
    Viscosity is resistance to flow, and is expressed as a number that is directly proportional to the thickness of the oil.
17. C
     Because they serve different purposes within an automobile, both negative ground current and direct current electrical systems are being built. Alternating current is used primarily for household appliances.
18. D
    Stick welding involves the use of an electric arc welding machine and two cables: one that attaches to the work being welded through a ground clamp, and the other going to an electrode that is sometimes referred to as a -stinger. For safety reasons, always clamp to the work.
19. D
    The last major cylinder arrangement that has been utilized by engine designers is the horizontally opposed or flat design. This has all of the cylinders lying on the horizontal plane, with half of the cylinders facing away from the other half and the crankshaft located between them. Some refer to this design as a “boxer” engine because the pistons move back and forth like a boxer throwing punches.
20. B
    The tool pictured is a drift. It is used for striking an object where it is important that the hammer itself does not come in direct contact with the work. A chisel normally has a long edge and is used for cutting (A), where a punch is narrow and is used for driving small fasteners and making layout marks (C). To guide a saw when cutting across the grain (D), you might use a miter box, but you would certainly not use a drift.
21. A
    This design is known as single overhead cam or SOHC. In a V-type engine with two cylinder heads, there would be two camshafts, with one installed above each cylinder head.
22. D
    Any air passing through to the car’s combustion chamber must naturally pass through the intake port in the cylinder head, the intake manifold, and the air filter. Since the intake valve is open and is allowing atmospheric air to enter the combustion chamber, higher -atmospheric air pressure pushes air through the engine’s intake system and toward the low-pressure area above the piston. As the air is traveling through the intake system, fuel is injected into the air stream before it enters the combustion chamber. Gases do not pass through the catalytic converter until they are almost ready to be expelled from the car.
23. D
    Since most nuts are smaller sized, and because the 6-point socket is a stronger design, it is usually the mechanic’s first choice in the smaller socket drive sizes. And a breaker bar attached to a socket can give enough twisting force to loosen very tight fasteners.
24. D
    This is an external hole-type -retaining ring. Retaining rings (or snap rings) are used to prevent end-movement of cylindrical parts in bores or parts mounted on shafts. External snap rings are installed in grooves on shafts, whereas internal snap rings install in grooves inside a bore. Snap rings are installed and removed using snap ring pliers.
25. B
    A car’s battery contains lead plates immersed in an electrolyte made up of sulfuric acid and water. When the battery discharges energy, the sulfur binds with the lead plates to make lead sulfate, and the electrolyte is reduced to water. Even though water is a result of this process, it is not true to say that (A) the lead plates release water, because the water is already part of the electrolyte mixture.