Mechanical Reasoning Practice Test: 20 Questions in 15 Minutes

Four sentences that carry most of the paper

Mechanical reasoning has a reputation for being the paper you either have a feel for or you do not. That is wrong, and it is an expensive thing to believe, because the whole subject rests on a handful of rules you can memorise in a few minutes. Say these four out loud until they are automatic.

• Meshed gears turn opposite ways. Every point of contact reverses the direction. Tooth counts change speed, never direction.

• Count rope segments, not pulleys. The force you pull with is the load divided by the number of rope segments actually holding the load up.

• Weight times distance balances a lever. Both sides of the pivot, same product.

• Ramps, screws and hydraulic pistons trade distance for force, and the trade is exact: whatever factor they multiply your force by, they divide your distance by the same factor.

That is the syllabus. Nearly every question on a mechanical aptitude test is one of these four rules with a diagram wrapped around it, and the fifth topic — hydraulics — is the fourth rule with areas instead of lengths.

Gears: direction is counting, speed is a ratio

Gear questions come in two flavours and they need different habits. Direction questions give you a train of gears and tell you which way the first one turns. Because every mesh reverses the direction, the answer depends only on how many gears there are: odd-numbered gears turn the same way as gear 1, even-numbered gears turn the opposite way. You do not need to trace the train with your finger, and you certainly do not need the tooth counts — a question that offers 'it depends on the number of teeth' as an option is testing whether you know that teeth never affect direction.

Speed questions are a ratio, and the ratio catches people out because it runs the opposite way to intuition. The teeth passing the contact point must match on both gears, so turns × teeth is equal on both sides. A 30-tooth gear driving a 10-tooth gear makes the small one spin three times for every one turn of the large one. The smaller gear always turns more. That sentence is the sanity check: after you calculate, ask whether your answer put the bigger number on the smaller gear. If it did not, you inverted the ratio.

Belt drives follow the same arithmetic with one wrinkle worth knowing: an open belt keeps both pulleys turning the same way, while a crossed belt reverses the second one. Gears reverse, open belts do not — mixing those two up is a common slip when a paper puts both on the same page.

Pulleys: count the rope, not the wheels

This is where most marks are lost on a mechanical reasoning test, and the cause is almost always the same: candidates count pulleys. The mechanical advantage of a pulley system has nothing to do with how many wheels you can see. It is the number of rope segments that actually carry the load.

A single fixed pulley bolted to a ceiling gives you no advantage at all. One segment holds the load, so you pull the full weight — what you gain is a change of direction, which is convenient but free of leverage. Bolt ten fixed pulleys up there and you still pull the full weight. A movable pulley, one that rides on the rope and moves with the load, is held up by two segments, so it halves your effort. Two movable pulleys give four segments and quarter it.

The reliable method takes five seconds: put your finger on the load and count every rope segment that runs upward from it or from the movable block carrying it. That count is your divisor. Then apply the check that catches the remaining errors — you cannot get more force out than you put in. If a system quarters your effort, you must pull four metres of rope to raise the load one metre. Any answer that gives you advantage for free is wrong.

Levers: the product, then the sanity check

A lever balances when weight × distance from the pivot is the same on both sides. Twenty kilograms three metres out balances sixty kilograms one metre out, because both make sixty. That is the entire rule, and the arithmetic is easy — which is exactly why the mistakes here are careless rather than conceptual.

The habit that prevents them: before you compute, say which side needs the heavier weight. The side closer to the pivot always needs more weight, because it has less distance to work with. Then compute, and check your answer against what you just said. If you predicted 'the right side is closer so it needs more' and your arithmetic came back lighter, you multiplied where you should have divided. This takes two seconds and catches the single most common lever error.

Papers also ask which of several arrangements takes the least effort to lift a load. Same rule, read backwards: the further your hand is from the pivot and the closer the load is to it, the less effort you need. A wheelbarrow puts the load close to the wheel and your hands far from it, which is why it works. When the question shows three tools and asks which is easiest, you are being asked to compare those two distances, nothing more.

Ramps, screws and hydraulics: one idea in three costumes

These three topics look unrelated on a page and are the same idea underneath. Each one lets you use less force by making you apply it over a greater distance, and the exchange is exact.

A ramp that is 12 metres long and rises 3 metres has a ratio of 3 to 12, so pushing a crate up it takes a quarter of the force of lifting it straight up — and you push it four times as far. A screw is a ramp wrapped around a cylinder: a fine thread with many turns per centimetre gives a big force multiplication and a slow advance, which is why a bench vice tightens hard but closes slowly. A hydraulic jack does it with area instead of length: pressure is the same throughout the fluid, so a piston six times the area pushes six times as hard while moving one sixth as far.

For all three the sanity check is identical and worth applying every time: force out × distance out equals force in × distance in. Nothing is gained. If your answer says a ramp needs more force than lifting the load straight up, or that a large hydraulic piston pushes less hard than the small one, you have the ratio upside down. Notice that this is the same error described in the gear and lever sections — which is the point of the next one.

One error, five topics: the inverted ratio

Look at the report after you submit and you may find your losses spread across all five topics, which feels like a general weakness. It usually is not. In our question set, one specific slip is available in every topic: running the ratio backwards.

It shows up as the small gear turning slower than the large one, as a load-lifting setup that demands more force than the load, as a lever that needs more weight further out, and as a hydraulic jack that shrinks the force instead of multiplying it. Five different diagrams, one habit. That is good news, because a single fix repairs all five.

The fix is to predict the direction before you calculate. Every one of these questions has a common-sense answer available before any arithmetic: the small gear spins faster; a pulley system makes lifting easier; the near side of a lever needs more weight; a big piston pushes harder. Say the direction, then do the arithmetic, then check the number agrees with the direction you said. Candidates who do this consistently gain marks without learning any new physics at all.

Who sets this test, and how it is scored

Mechanical reasoning appears in more hiring processes than most candidates expect. Apprenticeship entrance exams for electrical, plumbing and mechanical trades use it heavily. So do maintenance and technician roles across manufacturing, utilities and transport. Emergency services set it for firefighter and technical roles, military entrance batteries include a mechanical comprehension section, and some technical colleges use it for course admission.

Scoring is almost always a raw count of correct answers, converted to a percentile against other applicants for the same role rather than an absolute pass mark. Two consequences follow. First, guessing is usually correct strategy — there is rarely a penalty, and a partially informed guess beats a blank. Second, speed matters more than it appears: if most applicants finish and you do not, your percentile suffers even when your accuracy is good.

One practical note about the physical setups you will see. Real papers draw from a small stock of scenarios — gear trains, block and tackle, beam and fulcrum, ramp and crate, jack and pistons, occasionally a bicycle drivetrain or a set of belt-driven wheels. There is no long tail of exotic machinery to prepare for. Working through the five topics above genuinely covers the ground.

Pacing 15 minutes and reading your report

Twenty questions in fifteen minutes is 45 seconds each, which is generous compared with an abstract reasoning paper but tight if you re-read diagrams. Aim to spend the first ten seconds identifying which of the five topics a question belongs to, because that decides which rule you reach for. The remaining thirty-five is arithmetic and checking.

Hard rules for the clock: never spend more than 75 seconds on a question, and never leave one blank. If a diagram will not resolve, pick the option that agrees with the common-sense direction — small gear faster, pulley easier, big piston stronger — and move on. That guess is right far more often than chance.

The report splits your score five ways. If one topic is far below the others, read that section above and re-sit; a single missing rule is a fast fix. If the five are level but all mediocre, the problem is the inverted ratio rather than any one topic, and the direction-first habit is what to practise. If your accuracy is good but you ran out of time, do not add more papers — do the same one again with a stopwatch and force yourself to abandon anything that has cost more than 75 seconds. Sign in before you start and the score is saved to your account with a history for this paper alone, so next week's attempt is measured against this one.