ASVAB Auto and Shop Information, engines and tools

When cutting a metal bar held in a bench vise with a hacksaw, the cut should be made

1. with the bar held loosely.
   A loose bar shifts and twists under each stroke, which can snap the blade; the work must be clamped tight.
2. right next to the jaws.
   Sawing right next to the jaws keeps the bar rigid, so it cannot vibrate or chatter and the cut stays straight.
3. directly between the jaws.
   Sawing between the jaws cuts into the vise itself and ruins the jaw faces; the cut belongs just outside them.
4. as far from the jaws as possible.
   Far from the jaws the bar acts like a springboard and chatters, the very problem clamping is meant to stop.

ID 716078 · Report a problem

Which hand tool is pressed into wood to mark a point or start a small hole for a screw?

1. Center punch
   A center punch is struck with a hammer to dent metal so a drill bit will not wander; it is a metalworking tool.
2. Nail set
   A nail set has a blunt, cupped tip for driving a nail head below the surface; it does not start holes.
3. Scratch awl
   An awl has a sharp steel point that is pushed or twisted into wood by hand to mark a spot or start a pilot hole for a small screw.
4. Cold chisel
   A cold chisel is struck with a hammer to cut or shear metal, not pressed into wood.

ID 716081 · Report a problem

To fold a sheet-metal edge over a stake without denting or stretching the metal, it is struck with a

1. wooden mallet.
   A wooden or rawhide mallet has a soft face that bends thin sheet metal over the stake without denting or stretching it.
2. ball-peen hammer.
   A ball-peen hammer's hard, rounded peen is for shaping rivets and heavier metal; on thin sheet it leaves dimples and stretches it.
3. claw hammer.
   A claw hammer's hard steel face leaves dents in thin sheet metal; it is meant for driving and pulling nails.
4. cross-peen hammer.
   The narrow peen of a cross-peen hammer concentrates the blow, which dents and stretches thin metal.

ID 716085 · Report a problem

Which snips are designed to cut a tight curve to the left in sheet metal?

1. Yellow-handled aviation snips
   Yellow handles mark straight-cut aviation snips, which cut straight lines and wide curves either way.
2. Red-handled aviation snips
   Red handles mark the left-cut pattern, made to cut tight curves to the left.
3. Straight-pattern tin snips
   Straight-pattern tin snips have long blades for straight cuts and gentle curves, not tight curves.
4. Green-handled aviation snips
   Green handles mark right-cut snips, which cut tight curves to the right, the opposite direction.

ID 716089 · Report a problem

Compared with a file, a wood rasp

1. cuts slower but leaves a smoother surface.
   This reverses the trade-off: the file is the slower tool that leaves the smoother finish.
2. has no teeth, only an abrasive grit.
   Grit with no teeth describes sandpaper or a diamond file; a rasp has sharp, individual teeth.
3. cuts faster but leaves a rougher surface.
   A rasp has separate raised teeth that remove wood quickly but leave a coarse surface, which is then smoothed with a file or sandpaper.
4. is used mainly on hardened steel.
   Hardened steel would dull a rasp at once; rasps are for wood, plastic and other soft materials.

ID 716096 · Report a problem

On a table saw, which safety device directly helps prevent kickback?

1. Push stick
   A push stick keeps fingers away from the blade while feeding stock; it protects hands but does not stop the wood from pinching the blade.
2. Miter gauge
   A miter gauge guides a crosscut at a set angle; it does nothing to keep the cut from closing on the blade.
3. Clear blade guard
   The clear guard covers the blade so hands and chips cannot reach it; it does not hold the kerf open.
4. Riving knife
   A riving knife rides just behind the blade and keeps the kerf from closing and pinching the blade, which is what throws a board back.

ID 716097 · Report a problem

In a mortise-and-tenon joint, the tenon is

1. the rectangular hole in the leg.
   The rectangular hole is the mortise, the tenon's mate; the two names are easy to swap.
2. the tongue on the end of the rail.
   The tenon is the projecting tongue cut on the end of one piece; it fits into the mortise of the other.
3. the wedge that locks the joint.
   Some joints add a wedge to lock the tenon in place, but that wedge is a separate part, not the tenon.
4. the groove cut along the board's edge.
   A groove along an edge is a dado or the groove half of a tongue-and-groove joint, not a tenon.

ID 716105 · Report a problem

Valve float at very high rpm is most often caused by

1. worn valve guides.
   Worn guides let the valve stem wobble and pass oil, giving blue smoke; they do not stop the spring from closing the valve in time.
2. a loose fan belt.
   A slipping fan belt causes squeal, overheating or a weak charge, not valves losing contact with the cam lobe.
3. thick engine oil.
   Thick oil slows cranking and oil flow when the engine is cold, but it does not let the valves leave the cam at high rpm.
4. weak valve springs.
   Valve float happens when the spring cannot close the valve fast enough to keep the lifter on the cam; a tired, weak spring is the usual cause.

ID 716176 · Report a problem

A dirty mass airflow sensor that under-reports the incoming air makes the engine run

1. lean, with hesitation.
   The computer meters fuel to the air it thinks is coming in; if the sensor reads low, too little fuel is added and the engine runs lean and stumbles.
2. hotter, with coolant loss.
   Coolant loss comes from leaks or a failed head gasket, not from an airflow reading.
3. rich, with black smoke.
   Black smoke means too much fuel, which happens when the sensor over-reports air, the opposite fault.
4. with higher oil pressure.
   Oil pressure depends on the oil pump, oil thickness and bearing clearances, not on how air is metered.

ID 716184 · Report a problem

An oxyacetylene flame that shows a white, feathery cone around the inner cone has

1. too little gas pressure.
   Low pressure makes a weak flame that may pop or backfire; it does not create a feather.
2. too much oxygen.
   Excess oxygen makes an oxidizing flame with a short, pointed inner cone and no feather.
3. equal oxygen and acetylene.
   Equal gases give a neutral flame, with one clean inner cone and no feather.
4. too much acetylene.
   Extra acetylene that cannot burn forms a white feather around the inner cone; this is a carburizing flame.

ID 716294 · Report a problem

When wrapping PTFE thread-seal tape on a pipe's male threads, the tape is wound

1. clockwise, viewed from the pipe end.
   Looking at the open end of a pipe with right-hand threads, wrapping clockwise follows the threads, so screwing on the fitting tightens the tape instead of peeling it off.
2. over the threads and the first inch of pipe.
   Tape on bare pipe past the threads seals nothing; it should cover the threads only.
3. around the fitting's inside threads.
   Tape on female threads bunches up and can tear loose inside the pipe; it goes on the male threads only.
4. counterclockwise, viewed from the pipe end.
   Wrapping against the threads lets the fitting catch the tape's loose end and roll it off as it turns.

ID 716302 · Report a problem

An exhaust that suddenly becomes much louder most likely has

1. worn spark plugs.
   Worn plugs cause misfires, rough idle and poor fuel economy, not a sudden jump in exhaust noise.
2. a hole in the muffler or pipe.
   The muffler quiets the exhaust; a sudden roar means gas is escaping through a rusted or broken muffler or pipe before it is silenced.
3. a clogged catalytic converter.
   A clogged converter restricts flow, so power drops; it tends to muffle the exhaust, not make it louder.
4. a failed oxygen sensor.
   A bad oxygen sensor upsets the fuel mixture and lights the check-engine lamp; it does not change exhaust noise.

ID 716383 · Report a problem

In the tire size P215/65R15, the number 65 means the sidewall height is

1. 65 percent of the width.
   65 is the aspect ratio: sidewall height is 65 percent of the section width, here 215 mm, so about 140 mm.
2. rated for 65 psi.
   Inflation pressure is not part of the size code; the maximum pressure is printed separately on the sidewall.
3. 6.5 inches tall.
   Reading 65 as 6.5 inches treats a ratio as a measurement; the only inch figure in the code is the 15, the wheel diameter.
4. exactly 65 millimeters.
   Millimeters belong to the 215, the width; 65 is a percentage of that width, not a length.

ID 716390 · Report a problem

Using premium (higher-octane) gasoline in an engine designed for regular will usually

1. cause knocking and pinging.
   Higher octane makes knock less likely, not more; knocking comes from using too low an octane.
2. damage the catalytic converter.
   Premium is unleaded like regular; it does not harm the converter, it only costs more.
3. make little or no difference.
   Octane measures resistance to knock; an engine designed for regular does not knock on regular, so a higher rating adds nothing.
4. add noticeable horsepower.
   Premium holds no more energy than regular; it helps only engines tuned for high compression that need the extra knock resistance.

ID 716396 · Report a problem

At steady highway cruising, the torque converter's lock-up clutch engages to

1. shift the car into overdrive.
   Overdrive is a gear ratio selected by the transmission's own clutches and bands, not by the converter clutch.
2. let the engine idle in gear.
   The unlocked converter is what lets the engine idle in gear; the lock-up clutch is released at idle.
3. stop slip and save fuel.
   At cruise the lock-up clutch ties the converter's turbine to its impeller, so the fluid stops slipping and fuel economy improves.
4. multiply torque for passing.
   Torque multiplication happens while the converter slips, at low speed or hard acceleration; locking up ends it.

ID 716402 · Report a problem