Auto & Shop Information · Practice test 1

Correct answer: claw hammer

The claw hammer's forked back is designed to slip under a nail head and pry it out, in addition to its flat face for driving nails in.

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Correct answer: a thermostat stuck open

If the thermostat never closes, coolant keeps flowing to the radiator even when the engine is cold, so the engine loses heat continuously and struggles to warm up.

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Correct answer: snip (or tin snip)

Snips work like heavy-duty scissors, with jaws shaped and hardened to shear through thin sheet metal along straight or gently curved lines.

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Correct answer: removing trapped air from the hydraulic lines

Because trapped air compresses and makes the pedal spongy, bleeding pushes fresh fluid through each line at the wheel until only solid fluid, no bubbles, comes out.

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Correct answer: preventing the wheels from locking during hard braking

ABS releases and reapplies pressure many times a second when a wheel is about to lock, so the tyre keeps rolling and the driver keeps steering control. Its purpose is steering, not necessarily a shorter stop.

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Correct answer: seal the combustion chamber and control oil on the cylinder wall

Compression rings keep the burning gases above the piston and the oil ring wipes excess oil back down. Worn rings let combustion pressure escape and oil burn, which is why a tired engine loses power and smokes. The connecting rod is what joins piston to crankshaft.

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Correct answer: the driven wheels to turn at different speeds in a corner

In a turn the outer wheel travels further than the inner one, so they cannot be locked together without scrubbing the tyres. The differential splits the drive and lets each turn at its own rate. Sharing drive front to rear is the transfer case's job.

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Correct answer: make a dimple so the bit does not wander

A drill bit on smooth metal skates away from the mark. A tapped dimple gives the point somewhere to sit so the hole starts exactly where intended.

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Correct answer: smoothing a flat wooden surface with a light, swirling sanding action

The pad's small orbital motion removes material gradually and evenly, leaving a smooth surface with far less risk of gouging than aggressive sanding by hand.

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Correct answer: trap dirt and water before they reach the injectors

Injector openings are tiny and block easily, so the filter catches contaminants first. A clogged filter starves the engine and shows up as hesitation or stalling under load.

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Correct answer: grips all six corners of the fastener

Surrounding the nut spreads the load over every corner, so it is far less likely to round off a tight fastener. The open end's advantage is that it can slip on sideways where a closed ring will not reach.

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Correct answer: the work surface needs to be protected from denting or marring

The soft face absorbs some of the blow and will not gouge or mark a finished or delicate surface the way a hard steel face would.

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Correct answer: transfers some torque to the wheel with more traction when one wheel starts to spin

An open differential sends power to whichever wheel spins easiest, which can leave a stuck vehicle stranded; a limited-slip design resists that and shares torque with the wheel that still has grip.

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Correct answer: exhaust manifold

The manifold's individual runners join the exhaust ports on the head and combine the flow into a single pipe leading to the rest of the exhaust system.

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Correct answer: driven mechanically by the engine itself

A belt or gear from the crankshaft spins the supercharger, so it responds instantly but consumes engine power to run. A turbocharger takes its drive from exhaust that would otherwise be wasted, at the cost of a slight lag.

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Correct answer: keeps the battery topped up and runs the electrics

Belt driven off the engine, the alternator generates current to run the lights and ignition and to replace what starting drew from the battery. The battery is the component that stores charge.

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Correct answer: cylinder volume at the bottom of the stroke with volume at the top

It is how far the mixture is squeezed: a ratio of 10 to 1 means the space at the top is a tenth of the space at the bottom. Higher ratios extract more work but demand higher octane fuel, and diesels run far higher ratios than petrol engines. The second choice describes the air-fuel ratio, a different figure.

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Correct answer: a slipping clutch

A worn clutch disc cannot grip the flywheel hard enough to transmit full torque, so the engine races while the car does not. The same symptom in an automatic points to slipping bands or low fluid.

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Correct answer: drilling round holes in wood or metal

The spiral flutes cut on the leading edge and carry the chips out of the hole. It is the general-purpose bit; a Forstner bit makes the flat-bottomed recess and a spade bit makes large rough holes in wood.

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Correct answer: the opening and closing of the valves

Lobes on the rotating camshaft push the valves open at the right moment in the cycle. It is driven by the crankshaft, at half crankshaft speed, so that each valve opens once every two revolutions.

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Correct answer: the heat produced by compressing the air

Diesels compress air so hard that it becomes hot enough to ignite fuel injected into it, so they have no spark plugs at all. Glow plugs exist but only warm the chamber for starting in cold weather.

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Correct answer: The braking system

The master cylinder converts the pedal's push into hydraulic pressure and sends it along the brake lines to every wheel. It is the starting point of the whole hydraulic brake circuit.

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Correct answer: a parasitic draw from a component left on

Something continuing to pull current after the key is off, such as a stuck interior light or a faulty module, slowly drains the battery even though the alternator charges it fine during the day.

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Correct answer: maintains system pressure, which raises the coolant's boiling point

By sealing the system under pressure, the cap raises the temperature coolant can reach before boiling, letting the engine run hotter without the coolant turning to steam.

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Correct answer: cut threads on the inside of a hole

A tap cuts the female thread that a bolt screws into. Its counterpart, the die, cuts the male thread on the outside of a rod. Remembering that taps go into holes is the easiest way to keep them straight.

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