ASVAB Auto and Shop Information Practice Test: Engines, Vehicle Systems, Tools and Fasteners

The piston first draws in the air-fuel mixture (intake), squeezes it (compression), is pushed down by the burning mixture (power) and then pushes out the burned gases (exhaust).

The ignition system sends a high-voltage pulse to the spark plug, which fires a spark at the right moment. Glow plugs are used to help start cold diesel engines.

A diesel engine compresses air far more than a gasoline engine, which makes it very hot. When fuel is injected into this hot air it ignites by itself, so no spark plugs are needed.

The thermostat stays closed while the engine is cold so it warms up quickly, then opens to send coolant to the radiator. The water pump moves the coolant, and the fan pulls air through the radiator.

The alternator is turned by a belt from the engine and produces electricity for the lights, electronics and battery charging. The starter only uses battery power to crank the engine.

A catalytic converter uses metals such as platinum to change carbon monoxide, unburned fuel and nitrogen oxides into less harmful gases. Reducing noise is the job of the muffler.

Fluid pressure pushes the pistons in the caliper, and the caliper clamps the pads onto the spinning rotor. The master cylinder creates the pressure at the pedal; drums belong to drum brakes.

A crisscross pattern pulls the wheel evenly against the hub, so it seats flat and the brake rotor is not warped. Tightening the nuts one after another around the circle can seat the wheel unevenly.

A torque wrench shows or clicks at a set twisting force, for example in foot-pounds or newton-meters. Ordinary wrenches tighten the bolt but do not measure how tight it is.

A hacksaw has a fine-toothed blade held tight in a frame, made for cutting metal and plastic. Wood along the grain is cut with a ripsaw, and curves with a coping saw or jigsaw.

A micrometer uses a finely threaded spindle to measure small dimensions very precisely. A tape measure is for longer lengths, a square checks right angles and a level checks for horizontal.

The split, springy washer pushes against the nut and the surface, which helps hold the nut in place when the part vibrates. A flat washer, by contrast, mainly spreads the load.

A rivet is pushed through both pieces and its end is flattened (or pulled, for a pop rivet), so it cannot be unscrewed. Bolts, machine screws and wing nuts are made to be taken apart.

A plane holds a sharp blade at an angle and removes thin shavings as it is pushed along the board. Holes are drilled, boards are cut with a saw and nails are set with a nail set.

The number of lines marks the grade: for example, 3 lines mean Grade 5 and 6 lines mean Grade 8, which is stronger. A plain head usually means a low-strength bolt.