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How car jacks work – a guide on how to use them

Scissor jack supporting a car spare wheel

Car jacks: why you need one

A car jack is needed whenever you need to raise your car to carry out an emergency repair – such as to change a wheel when you get a puncture – or if you need to spend more time under it, to renew the engine oil or replace the exhaust system, for example. If you're going to be working under the car you should also use axle stands, just in case the jack fails. 

There are three main types of car jack: the trolley jack, bottle jack and scissor jack. They all do fundamentally the same thing, but in a slightly different way, and some types are more stable than others (as we explain below).

Scissor jack

Scissor Jack

A scissor jack is the one you'll usually find in your boot, together with a spare wheel. It's the cheapest and smallest option available and comes with a detachable handle to wind the arms apart, which then lifts the car up.

Position it under the jacking point (your Haynes Manual or car handbook will show you where they are), making sure it's on firm, level ground (not grass or gravel) and wind it clockwise until the wheel is lifted off the ground. To lower it, it is simply a case of winding the handle the other way.

Trolley jack

Trolley Jack

The trolley jack is a safer, more stable and quicker option and is the choice of many professional mechanics. The wheels mean you can roll it into position easily, but before you do, start by making sure this little lever is turned to the right, which you can do using the end of the handle.

Then it is simply a case of inserting the handle and pumping it until this cradle reaches the jacking point. To lower it back down, take the handle out and twist the little lever anti-clockwise, taking care to do so steadily to lower the car slowly.

Bottle jack

Bottle Jack

The bottle jack works in much the same way as a trolley jack, using hydraulic force to lift the car up. It has the bonus of being smaller and easier to store than a trolley, but this means it isn’t quite as stable.

Again, make sure the lever is set to the right, then unscrew the top of the jack to the correct length – the instructions should tell you how far you need to extend it. Then position it under the jacking point, insert the handle and pump until the car is raised.

Lower it again in the same way as the trolley jack. Finally, and most importantly, you should never rely on a jack alone while working underneath a car, and should always use axle stands to support it.

How to use a jack: watch this video

How do axle stands work?

If you plan on raising the car because you need to get under it, then yes, you'll need axle stands to support the car safely. You must never get under the car with just the jack supporting it.

As with any type of car jack, axle stands must only be used on firm, level ground. Make sure the ones you buy can support the weight of your vehicle.

Trolley jack and axle stands