A mechanical reasoning test asks you to apply everyday physics to a picture of a machine: levers, pulleys, gears, belts, springs, pressure, fluids and simple electrical circuits. Unlike most aptitude tests, it draws on knowledge you either hold or do not, which is what makes it the one reasoning test where revision changes your score directly. Prepare by relearning the handful of principles below until you can apply them without stopping to think, then practise complete tests under the clock.
The topics the questions are built from
Levers
A lever turns about a fulcrum and balances when the turning effects on each side match: the load multiplied by its distance from the fulcrum equals the effort multiplied by its distance. Move the effort further out and you need less of it. A 600 N load sitting 1 m from the fulcrum is balanced by 200 N applied 3 m out on the other side, because 200 times 3 matches 600 times 1.
Most lever questions turn on which class of lever is shown. In a first class lever the fulcrum sits between the effort and the load, as in a crowbar or a pair of scissors. In a second class lever the load sits between the fulcrum and the effort, as in a wheelbarrow, so the effort arm is always the longer one and the tool always multiplies your force. In a third class lever the effort is applied between the fulcrum and the load, as in tweezers or your own forearm, which costs you force but moves the load further and faster.
Pulleys
A single fixed pulley bolted to a beam does not reduce the force needed. It changes the direction of the pull, so you can haul down instead of lifting up. The saving comes from movable pulleys, and the way to read any arrangement is to count the rope sections that actually support the moving load. With two supporting sections a 200 N load needs roughly 100 N of effort; with four sections, roughly 50 N.
Nothing comes free. The rope you pull travels further in the same proportion, so lifting that load by 1 m through a two section arrangement means pulling 2 m of rope. If a question asks which set-up needs the least effort, count the supporting sections and pick the highest. If it asks which lifts the load fastest for a given pulling speed, pick the lowest.
Gears and belts
Two gears that mesh turn in opposite directions. Put a third in line and it turns the same way as the first, so along a row of meshed gears the odd numbered ones share the driver’s direction and the even numbered ones oppose it. A gear placed in the middle purely to bridge a gap changes direction only, never the overall speed ratio.
Speed runs inversely to tooth count. A 10 tooth gear driving a 30 tooth gear turns it once for every three turns of its own, so the larger gear runs at a third of the speed and delivers three times the torque. Small driving large is a reduction: slower and stronger. Large driving small is the reverse: faster and weaker.
Belts follow the same speed rule, because the rims travel at the same rate and the smaller wheel has to turn more often to keep up. Direction is where they differ. An open belt keeps both wheels turning the same way; a crossed belt reverses the second one.
Springs
Within its working range a spring stretches in proportion to the force applied to it. Hang a weight from two identical springs joined end to end and each spring still carries the full weight, so each stretches as much as a single spring would and the total extension doubles. Put the same two springs side by side carrying that weight between them and each takes half of it, so the extension halves. End to end is softer, side by side is stiffer.
Pressure and fluids
Pressure is force divided by area, which is why a narrow heel presses into soft ground far harder than a flat sole carrying the same weight. In a sealed hydraulic system the pressure is the same throughout the fluid, so a small piston can drive a much larger one. Push with 50 N on a piston of 2 square centimetres and the pressure is 25 N per square centimetre; a 20 square centimetre piston at that pressure delivers 500 N. The force is multiplied by the ratio of the areas, and the small piston has to travel ten times as far as the large one moves.
Two other fluid facts recur. Pressure in a standing liquid depends on the depth, not on the width or shape of the container, so two differently shaped vessels filled to the same level have the same pressure at the bottom. And a liquid flowing along a pipe speeds up where the pipe narrows, because the same volume has to pass every second.
Electrical circuits
In a series circuit there is one path, the same current flows through every component, and the supply voltage divides between them. Break the loop anywhere and everything stops, which is why a single failed lamp in a series string takes the rest with it. Adding lamps in series raises the total resistance and dims them all.
In a parallel circuit each branch sees the full supply voltage and has its own route back. Break one branch and the others carry on unchanged. Adding branches lowers the total resistance, so the current drawn from the supply rises. A switch in a branch controls that branch alone; a switch in the main line controls the lot.
Screws, ramps and energy
A screw is an inclined plane wrapped around a cylinder. A finer thread needs more turns to advance the same distance and less force on each turn, which is the same trade a ramp makes: longer and shallower means less force and more distance. The wider principle behind every one of these devices is that a machine can trade force against distance but cannot create energy, so any arrangement that reduces the force you apply increases the distance you move.
Ten ways to prepare
1. Find out whose test you are sitting
Mechanical tests come from several publishers, including Bennett, Ramsay, Criteria and SHL, and they differ in length, timing and how heavily they lean on industrial equipment rather than everyday objects. Ask your recruiter which assessment you have been invited to, then look up its format and time limit before you plan anything else. The physics is common to all of them, so this shapes your practice rather than your revision.
2. Match the topics to the role
Read the job description and list the mechanical concepts that appear in it. A maintenance role is likely to lean on gears, belts, bearings and hydraulics; an electrical role will weight circuits more heavily. Testing is often tailored to the work, so that list is a fair guide to where your revision time is best spent.
3. Revise the principles, not memorised answers
Learn each rule in a form you can apply to an unfamiliar picture: effort arm against load arm, supporting rope sections, tooth counts, area ratios. A memorised answer to a specific diagram is worth nothing when the diagram changes, whereas the underlying rule transfers to every version of the question.
4. Keep your units straight
Where a question asks for a number, note the units before you calculate and check that the answer carries the right ones. Force in newtons, area in square centimetres and pressure in newtons per square centimetre have to line up. A large share of avoidable errors come from a length given in millimetres and used as though it were centimetres.
5. Practise complete tests under timed conditions
Sitting a full test is different from working through questions one at a time, because pacing and fatigue only show up over a whole paper. Complete tests end to end, with the clock running, and treat the score as information rather than a verdict.
6. Read every diagram in the same order
Build a fixed routine and stick to it: identify the input, follow the path of the force or motion through each component, then read the question again to check what is actually being asked. Working in a consistent order stops you answering a question about direction when the question was about speed. Keep paper beside you, because holding a linkage in your head is harder than sketching it.
7. Treat the answer options as suspects
Multiple choice does not make a test easier. Wrong options are written to catch the obvious slip: the gear turning the other way, the ratio inverted, the force before the mechanical advantage is applied. Work out your own answer from the diagram first, then look for it among the options rather than picking the one that feels familiar.
8. Drill the topics you get wrong
Review each practice test by topic rather than by score. If pulleys are costing you marks, work on pulleys in isolation until the counting rule is automatic, then return to mixed tests. Broad practice keeps you fluent, but targeted practice is what moves a weak topic.
9. Budget your time, and move on when stuck
Divide the time limit by the number of questions to get your working pace, which is often well under a minute per question. If a question resists you, take the best supported option and move on, unless the test marks wrong answers negatively. An unanswered easy question at the end costs the same mark as a hard one you never cracked.
10. Set up properly, then track your progress
These tests are usually taken online in timed conditions, so check your connection, update your browser and clear your desk before you start. Then keep a simple record of scores by topic across your practice sessions, so you can see which areas are improving and which still need the time. Working through free aptitude tests alongside your mechanical practice is a useful way to warm up, and reviewing aptitude test sample questions and answers shows you the reasoning behind each answer. If your role also involves reading technical drawings, spatial reasoning tests are worth adding to the mix.
