A jack is built to lift a car, not to hold it there. Its hydraulic seal, its footprint on the ground and its single point of contact under the vehicle can all fail or shift while someone is underneath. Axle stands are designed to bear that weight safely and stay put; a jack on its own is not.
Why does a jack alone put a car at risk?
A jack alone is risky because it is a lifting device, not a support device, and it can fail in several ways at once: a seal can weep, a release valve can be nudged, the ground under the small jack pad can give way, or the car itself can shift on that single contact point.
None of these failures need to be dramatic to be dangerous. A jack does not need to collapse suddenly to hurt someone — it only needs to drop a few centimetres while a hand, an arm or a head is underneath the car. Even a small, slow settling movement can be enough to trap a limb or crush a person working on a brake line, an exhaust clamp or a suspension bolt.
How does a jack actually work — and why is that the problem?
Most trolley and bottle jacks work hydraulically: a small pump pushes fluid into a cylinder, and that fluid pressure lifts a ram. The car’s weight is held up by that trapped fluid and by a release valve that stays closed until someone opens it.
That is a good way to raise a car a little way off the ground. It is a poor way to hold thousands of kilograms up for the length of time it takes to change a brake pad, inspect an exhaust or drop a subframe. Seals wear, fluid can find a way past them, and a jack that was rock solid five minutes ago can settle without warning. The jack was never rated as a support — check its own documentation and it will say so.
What do axle stands add that a jack cannot?
Axle stands are mechanical, not hydraulic. Weight rests on a solid pin through a ratcheted column, so there is no seal to fail and no fluid to leak. Once the pin is set in a notch, the height cannot creep down the way a hydraulic ram can.
They also spread load differently. A jack typically lifts from one point — a jacking rail, a chassis rail or a specified lift point. Axle stands are positioned under structural points of the car and left there for the whole job, while the jack itself is lowered away completely once the car is settled on the stands. The full article on what a trolley jack and axle stands are each actually for covers how the two tools divide that job between them.
What is the right sequence for raising and supporting a car?
The safe sequence keeps the jack doing only the lifting, and the stands doing all of the holding, with no point where the car’s full weight rests on the jack while anyone is underneath it.
- Park on a flat, level, solid surface and apply the parking brake.
- Chock the wheels that will remain on the ground, on both sides, before lifting begins.
- Lift at the manufacturer’s specified jacking point — check the vehicle handbook, not a guess at the nearest rail.
- Position axle stands under a load-bearing point close to the jacking point, following the vehicle’s own guidance for where the car can be supported.
- Lower the car onto the stands and confirm it is settled and stable before removing the jack from underneath.
- Only then work under, around or near the raised end of the car.
The jack comes out from under the car entirely once the stands are doing the work. It is not left in place “just in case” — a jack left partially loaded is a jack that can still drop.
What ground and surface conditions matter?
The surface under both the jack and the stands has to be solid, flat and level, because a tilted or soft base is one of the most common reasons a jack or a stand shifts once weight is on it.
Soft ground, gravel, a slope, or a driveway with a pronounced camber can let a jack’s small base tip sideways under load, or let an axle stand’s feet sink unevenly. A smooth, solid concrete or similarly firm floor is the baseline most guidance assumes. If the only available surface is uneven, that is a reason to choose a different location for the job rather than to compensate with extra props, offcuts of wood or bricks under a stand’s foot.
What else besides axle stands helps prevent a car rolling or falling?
Wheel chocks at both the front and back of at least one wheel that stays on the ground stop the car rolling while it is raised, and they matter whether the handbrake is applied or not, since a handbrake alone is not a guarantee on every surface or every car.
Working through both sides of a job — for example, one wheel off — still calls for chocking the wheels that remain grounded, because a car balanced on stands with an unchocked wheel can still roll or tip if it is nudged, if a component is levered against, or if weight shifts as a part comes free.
A second person nearby, out of the danger zone but aware the work is happening, is a reasonable precaution for anything that involves being fully underneath the car for a sustained period.
What PPE and precautions matter when working underneath a car?
Eye protection matters for anything that can drop grit, rust flakes, brake dust or fluid from above while working underneath a raised car, and gloves suited to the task protect against sharp edges, hot components and fluids that should not contact skin.
Loose clothing and anything that can catch on a rotating part or a moving component underneath the car is worth checking before starting — the reasoning behind that is the same one covered in why loose sleeves and gloves matter around rotating tools, and it applies just as much to work done lying under a car as it does at a bench.
A basic first-aid kit within reach of the work area, stocked for cuts, crush injuries and eye contamination, is worth having before the car goes up rather than after something goes wrong — see what should be in a workshop first aid kit for what that actually needs to include.
What should be checked before buying axle stands or a jack?
The comparison that matters is rated capacity against the actual weight of the car being worked on, not the price or the size of the box, since a stand or jack rated below the vehicle’s weight offers no real margin at all.
Worth comparing before buying:
- The stated maximum capacity of the stands or jack, checked against the vehicle’s kerb weight with a sensible margin, not the bare minimum.
- The stand’s base footprint and how stable it feels fully extended, since a taller, narrower stand is inherently less stable than a shorter, wider one at the same capacity.
- The condition of a locking pin or ratchet mechanism, particularly on second-hand equipment — worn or bent parts are a reason to pass, not a reason to negotiate on price.
- Whether the jack’s own documentation specifies it as a lifting device only, which almost all consumer jacks do.
For a broader look at how to weigh up capacity, materials and price when buying equipment like this, the buying tools guide covers what to compare in specifications generally, and the automotive category and safety and PPE category both cover related ground for anyone building up a home workshop for car work. A wider look at workshop layout and habits that reduce injury generally is in why a tidy workshop cuts injuries.
Does a well-known brand of jack change any of this?
No — brand, price and build quality change how reliably a jack lifts and how long its seals last, but they do not change what the jack is designed to do. Every jack, however well made, is a lifting tool, and every manufacturer’s own manual says its purpose ends once the car is safely up and the stands are in place.
The habit that matters is not which jack sits in the garage. It is never treating the moment the car is off the ground as the moment it is safe to work underneath it — that moment only arrives once the weight is fully on stands, the jack is out, and the wheels still on the ground are chocked.
Find Tool publishes general information, not professional advice. Power tools, mains electricity and workshop machinery are genuinely dangerous, and the safe settings, guards and procedures differ between models — always follow the manual and the markings on the tool in front of you rather than a general guide. Never remove or defeat a guard or safety feature. Anything involving fixed wiring, gas or structural work belongs to a qualified tradesperson. Wear the eye, ear and respiratory protection the task calls for.
Featured image: Photo by Shixart1985, source, CC BY 2.0