Mechanical Reasoning Test: Principles and Practice

A mechanical reasoning test shows you a drawing of a mechanism, such as two gears, a see-saw or a rope over a pulley, and asks a simple-sounding question: which way does it turn, how much force do you need, which bulb lights up. The physics is school level. What makes the test hard is speed and the handful of traps that catch people who rely on gut feeling.

Employers use these tests for engineering apprenticeships, maintenance and production roles, technicians, the armed forces, emergency services and skilled trades. This guide explains who publishes the main tests, the principles that come up again and again (with the physics stated correctly), eight practice questions and a two-week plan.

What a Mechanical Reasoning Test Measures

A mechanical reasoning (or mechanical comprehension) test measures how well you understand physical principles and apply them to unfamiliar situations. It is not an engineering exam. You will not be asked to name a component or recall a specification. You will be asked to predict what happens.

Two things drive your score:

Knowing a small set of rules. Levers balance by moments, pulleys trade force for distance, meshing gears reverse direction, and so on.
Reading diagrams fast and accurately. Which gear is the driver, where the fulcrum sits, which strands of rope actually hold the load.

Most items have three or four options and a picture. Some ask "which is more" (A, B, or both equal), which is a common format for the classic Bennett-style items.

Who Publishes Mechanical Reasoning Tests

Bennett Mechanical Comprehension Test (BMCT-II)

The Bennett test is the best-known mechanical test, published by Pearson TalentLens. According to TalentLens, the current BMCT-II has 55 items in 25 minutes, is item-banked (so candidates get different sets) and can be taken online, including unsupervised. TalentLens says it measures mechanical reasoning and spatial perception, with content areas that include electricity, heat and hydraulics, and lists users in engineering, airlines, emergency services and skilled trades. It is available in several languages, including UK and US English.

Military tests

The US ASVAB includes a Mechanical Comprehension subtest, which the official ASVAB site describes as knowledge of mechanical and physical principles, alongside Electronics Information, Auto Information and Shop Information. Our ASVAB test guide covers those sections in detail. The British Armed Forces and other militaries use their own technical selection tests; see our overview of aptitude tests for military selection.

Other publishers

Other publishers have mechanical or technical reasoning tests in their catalogues too, and candidates most often report SHL and Saville Assessment versions. These are sometimes combined with spatial and diagrammatic sections in a single technical battery. Timings and item counts vary by product and employer, and candidates report that many employer versions are shorter than the Bennett. Your invitation is the reliable source for your own test. If your battery also includes rotation or cube-net items, read our spatial reasoning test guide.

The Principles You Need

Levers and moments

A lever balances when the turning effect (moment) on each side of the pivot is equal:

force x distance from pivot (left) = force x distance from pivot (right)

So a 200 N load 1 m from the pivot balances a 100 N effort 2 m from the pivot. The longer the distance from the pivot, the less force you need. That is why a long spanner loosens a stuck bolt more easily.

Lever classes matter less than the rule, but they help with diagrams:

First class: pivot between effort and load (see-saw, crowbar).
Second class: load between pivot and effort (wheelbarrow). Always gives a force advantage.
Third class: effort between pivot and load (tweezers, your forearm). Always needs more force than the load, but moves the load further and faster.

Pulleys

A single fixed pulley changes the direction of the force but not its size: lifting 100 N still takes 100 N (ignoring friction). A single movable pulley, where the pulley hangs on the load, halves the force needed but you pull twice as much rope.

The general rule for ideal pulley systems: effort = load / number of rope sections supporting the load. Count the strands that hold up the moving block, not the strand you pull on if it runs down from a fixed pulley. The trade-off is distance: with four supporting strands you need a quarter of the force but pull four times as much rope.

Gears

Two meshing gears turn in opposite directions.
In a chain of gears, each gear reverses direction again, so gears 1, 3, 5 turn one way and 2, 4 the other.
An idler gear between two gears changes direction but not the speed ratio.
Speed is inversely proportional to the number of teeth. A 10-tooth gear driving a 30-tooth gear makes the big gear turn at one third of the speed, but with three times the turning force (torque).
Two gears fixed on the same shaft turn at the same speed and in the same direction.

Belts and chains

An open (uncrossed) belt makes both wheels turn the same way. A crossed belt reverses direction. Speed again depends on size: the smaller wheel turns faster. A bicycle chain works like an open belt.

Electrical circuits

Series: components on one loop. The same current flows through all; total resistance is the sum (R = R1 + R2). If one bulb breaks, all go out.
Parallel: components on separate branches. Each branch gets the full supply voltage; total resistance is lower than the smallest single resistance (1/R = 1/R1 + 1/R2). If one bulb breaks, the others stay lit.
Ohm's law: voltage = current x resistance (V = IR).
A switch only affects the part of the circuit it sits in. A closed switch wired across a bulb (in parallel with it) short-circuits that bulb, so it goes out.

Two identical bulbs in parallel on a battery each glow as brightly as one bulb alone would; in series each glows more dimly.

Liquids, pressure and hydraulics

Pressure in a liquid increases with depth, which is why water leaves the lowest hole in a tank fastest.
In a hydraulic system, pressure is passed on equally: force / area is the same on both pistons. A small force on a small piston gives a large force on a large piston, but the large piston moves a shorter distance.
In a pipe that narrows, the same volume of liquid passes every second, so the liquid flows faster in the narrow section.

Stability, inclines and motion

An object is more stable with a lower centre of gravity and a wider base.
A longer, shallower ramp needs less force to push a load up than a short, steep one to the same height, but you push it further.
Ignoring air resistance, objects of different mass dropped from the same height land at the same time.

Practice Questions

Our own items. Diagrams are described in words; work from the description.

Practice question 1

A uniform plank rests on a pivot. A 300 N box sits 1 m to the left of the pivot. How much downward force, applied 3 m to the right of the pivot, balances it?

A. 900 N B. 300 N C. 150 N D. 100 N

Answer: D. Moments: 300 N x 1 m = 300 Nm. To balance, F x 3 m = 300 Nm, so F = 100 N.

Practice question 2

Gear A has 20 teeth and turns clockwise at 60 rpm. It meshes directly with gear B, which has 40 teeth. How does gear B turn?

A. Clockwise at 120 rpm B. Anticlockwise at 30 rpm C. Anticlockwise at 120 rpm D. Clockwise at 30 rpm

Answer: B. Meshing gears turn in opposite directions, so B turns anticlockwise. B has twice as many teeth, so it turns at half the speed: 30 rpm.

Practice question 3

Three gears sit in a row: A meshes with B, and B meshes with C. A turns clockwise. Which way does C turn?

A. Clockwise B. Anticlockwise C. It does not turn D. It depends on the number of teeth

Answer: A. A clockwise makes B anticlockwise, which makes C clockwise. Tooth numbers change speed, not direction.

Practice question 4

A load of 400 N hangs from a movable pulley block. Four sections of rope support the block. Ignoring friction and the weight of the pulleys, what effort is needed to hold the load?

A. 400 N B. 200 N C. 100 N D. 1,600 N

Answer: C. Effort = load / supporting sections = 400 / 4 = 100 N. You would pull 4 m of rope to lift the load 1 m.

Practice question 5

Two 6-ohm resistors are connected in parallel to a 12 V battery. What current does the battery supply?

A. 1 A B. 2 A C. 4 A D. 6 A

Answer: C. Two equal resistors in parallel give half the resistance: 3 ohms. I = V / R = 12 / 3 = 4 A.

Practice question 6

In a hydraulic jack, the small piston has an area of 2 cm² and the large piston an area of 20 cm². You push the small piston with 50 N. What force does the large piston produce?

A. 25 N B. 50 N C. 100 N D. 500 N

Answer: D. The pressure is equal on both: 50 N / 2 cm² = 25 N per cm². On 20 cm² that gives 500 N.

Practice question 7

Wheel X drives wheel Y with a crossed belt. X turns clockwise. Wheel Y has half the diameter of X. How does Y turn?

A. Clockwise, slower than X B. Clockwise, faster than X C. Anticlockwise, slower than X D. Anticlockwise, faster than X

Answer: D. A crossed belt reverses direction. The smaller wheel must turn faster to keep up with the belt, here twice as fast.

Practice question 8

Water flows through a horizontal pipe that narrows from a wide section to a section half as wide. Where does the water flow fastest?

A. In the wide section B. In the narrow section C. The speed is the same in both D. It depends on the water temperature

Answer: B. The same volume passes each point every second, so it must move faster where the pipe is narrower.

Scoring and Results

For most mechanical tests your raw score (number correct) is compared with a norm group, such as apprentices, technicians or skilled trade applicants, and reported as a percentile. The employer sets the bar for each role. Publishers rarely publish pass marks, and anyone quoting a universal pass mark is guessing.

On most tests there is no published penalty for wrong answers, so do not leave items blank when time is short; but read the instructions to confirm.

Common Mistakes

Counting the wrong rope strands. Only strands that support the moving block count.
Forgetting that gears reverse. Trace the direction from gear to gear with your pen.
Mixing up speed and force. A bigger gear turns slower but with more torque. Questions often ask for one and offer the other as a distractor.
Assuming heavier means faster falling. Without air resistance, it does not.
Spending too long on one diagram. With about half a minute per item on the Bennett, mark and move.

A Two-Week Preparation Plan

1. What should I do in days 1 to 3?

Learn the rules above until you can state each one from memory: moments, pulley rule, gear direction and ratio, series and parallel, hydraulic pressure. Explain each to someone else or write it on a card.

2. What should I do in days 4 to 7?

Practise one topic per session for 20 minutes, untimed, and check every answer. Draw arrows on gear trains and count rope strands with a pencil until it becomes automatic.

3. What should I do in days 8 to 12?

Switch to mixed, timed sets. Aim for the pace of your real test. If you are sitting the Bennett, that means 55 items in 25 minutes.

4. What should I do in the last two days?

Do one full timed simulation, review mistakes by topic and stop there. Sleep matters more than one extra set.

If your role also requires numerical tests, add short sessions from our numerical reasoning test guide. For timed mechanical, spatial and numerical practice in one place, see our all-tests package.

Frequently Asked Questions

What is on a mechanical reasoning test?

Mostly diagrams of everyday mechanisms: levers, pulleys, gears, belts, springs, simple electrical circuits, liquids under pressure and objects in motion. You answer which way something turns, how much force is needed or what happens next.

How long is the Bennett Mechanical Comprehension Test?

According to Pearson TalentLens, the BMCT-II has 55 items with a 25-minute time limit. It is item-banked, so different candidates see different questions.

Do I need to know formulas for a mechanical reasoning test?

Very few. The lever balance rule, the pulley rule, gear ratios and the basics of series and parallel circuits cover a large share of items. Most questions test whether you can apply these ideas quickly, not whether you can derive them.

Can I use a calculator on a mechanical reasoning test?

Usually not, and you rarely need one. The arithmetic is kept simple on purpose. Check the instructions for your test, but plan to work with rough paper and mental arithmetic.

Which jobs use mechanical reasoning tests?

Engineering apprenticeships, maintenance and production roles, skilled trades, the armed forces, emergency services and airline technical roles are common users. TalentLens lists engineering, airlines, emergency services and skilled trades among the areas where the Bennett test is used.

About the author

Ingmar van Maurik is a specialist in test and interview preparation who helps candidates perform better in recruitment processes.

References

TalentLens, Bennett Mechanical Comprehension Test: https://www.talentlens.com/recruitment/assessments/bennett-mechanical-comprehension-test.html Official ASVAB, What to expect: https://www.officialasvab.com/applicants/what-to-expect/