Auto & Shop Information · Practice test 3

Correct answer: router or a dado blade set on a table saw

A router fitted with a straight bit, or a table saw stacked with a dado blade set, removes a controlled width of material to leave a flat-bottomed groove of the right size.

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Correct answer: air trapped in the clutch hydraulic line

Just as with brakes, a hydraulic clutch relies on incompressible fluid; trapped air compresses under pedal pressure and produces a soft, spongy pedal feel.

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Correct answer: in a single straight row

Inline, or straight, layouts place every cylinder in one row along the crankshaft, which is the simplest and most common arrangement for four-cylinder engines.

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Correct answer: the piston to the crankshaft

It carries the force of combustion from the piston down to the crankshaft throw, pivoting at both ends as the piston rises and falls.

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Correct answer: carry waste material up and away from the hole being drilled

As the bit cuts, the flutes act like a screw conveyor, lifting chips out of the hole so they do not pack in and bind the bit.

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Correct answer: a broken timing belt

If the belt breaks the crankshaft can still turn the starter over, but the valves stop opening and closing in time with the pistons, so no cylinder can build compression.

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Correct answer: open-end wrench

An open-end wrench has a U-shaped opening at each end, sized to slip onto a bolt or nut from the side, useful where a socket cannot reach around.

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Correct answer: worn engine bearings increasing clearance at low pump output

Worn bearings widen the clearance oil must fill, and at idle the pump's slower output cannot maintain pressure through that larger gap; higher rpm speeds up the pump enough to mask the problem temporarily.

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Correct answer: add resistance and make the engine hard to start

Corrosion is a poor conductor, so it chokes the very large current the starter needs even though it may pass enough for the lights. Cleaning the posts and clamps often cures a no-start that looks like a dead battery.

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Correct answer: a groove cut across the grain to receive the edge of another board

A dado is a slot cut into the face of a board, running across the grain, sized so a shelf or panel edge can slide into it for a strong, self-aligning joint.

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Correct answer: in two banks set at an angle to each other

The V shape lets six cylinders sit in a shorter, lower block than a straight six would need. A flat or boxer layout has the banks opposed at 180 degrees.

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Correct answer: moisture tracking across old or cracked spark plug wires

Cracked insulation lets high voltage arc to ground through a film of water on the wire's surface instead of reaching the plug, which clears up once things dry out.

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Correct answer: starter solenoid

When the key is turned, the solenoid both closes the heavy circuit feeding the starter motor and pushes its pinion gear into mesh with the flywheel's ring gear.

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Correct answer: the type of tree the wood comes from

Hardwood comes from broadleaf trees that shed their leaves and softwood from conifers, and the labels say nothing reliable about hardness. Balsa is a hardwood and is soft enough to dent with a thumbnail, while yew is a softwood and is tough.

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Correct answer: brake shoes

Shoes are the drum brake's equivalent of disc brake pads: curved friction linings that expand outward inside the rotating drum to slow the wheel.

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Correct answer: the system has detected a fault and disabled anti-lock function, though normal brakes still work

ABS runs a self-check at startup; if it finds a fault such as a bad wheel speed sensor, it disables itself as a precaution but leaves the base hydraulic brakes fully functional.

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Correct answer: from the transmission to the differential

On a rear-drive vehicle the driveshaft is the long tube running down the middle of the car to the rear axle. From the differential outward, the axle shafts take over.

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Correct answer: lifter or follower

The lifter, also called a tappet or follower, rests against the cam lobe and passes the lobe's lift upward through the pushrod or directly to the valve.

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Correct answer: strong mechanical interlock that resists being pulled apart

The dovetail's angled, interlocking pins and tails physically resist being pulled straight apart, which is why it remains a hallmark of strong drawer and box construction.

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Correct answer: four-wheel and all-wheel drive vehicles

The transfer case splits drive from the transmission between the front and rear axles, and usually offers a low range for difficult ground. A two-wheel drive vehicle has no need of one.

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Correct answer: clamp onto work and hold without being gripped

An over-centre mechanism locks the jaws shut so they stay clamped, which frees both hands and lets them serve as a temporary handle on a rounded or broken fastener.

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Correct answer: turn the engine over until it runs on its own

The starter draws a large current from the battery to crank the crankshaft fast enough for the engine to fire, then disengages. It is the heaviest single electrical load in the vehicle.

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Correct answer: guide the screw and stop the wood splitting

The screw wedges the wood fibres apart as it enters, and near an end or edge that force splits the board. A pilot hole removes the material the shank would displace. Recessing the head is countersinking, a separate operation.

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Correct answer: match engine speed to road speed through different gear ratios

An engine makes useful power over a narrow speed band, so gears trade speed for torque to keep it in that band from a standstill to highway speed. It changes how power is delivered rather than creating more of it. Letting the wheels differ is the differential's job.

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Correct answer: converts the pistons' up and down motion into rotation

Offset throws on the crankshaft turn the reciprocating motion of each piston into the rotation that eventually reaches the wheels. Valve operation is the camshaft's job.

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