Car Jacks: What are they, how do they work & how do I use them on my car?
Tuesday, 9 July 2019
What is a car jack?
Unless your car has run-flat tyres or you’re swift with applying the temporary fix afforded by a can of tyre sealant, then at some point you’re going to need to use a car jack.
It’s a ritual for vehicle owners everywhere when that inevitable flat happens, although if you're lucky you might get to watch someone else do it for you.
There are different varieties of car jacks and they all have the same purpose - to lift a heavy vehicle to change a tyre or carry out mechanical repairs.
You basically have three types, mechanical, hydraulic and electric. But which one is best for you? First, let’s see how they work.
How do car jacks work?
Mechanical: Uses a mechanically operated screw arrangement to lift and lower, by means of a ratcheting system.
Scissor jack: Most vehicles come with a scissor jack. This jack uses a central threaded screw to lift or lower two connecting scissor-action arms. They are compact, light and easy to operate and have low clearance. The only downside is they are manual and take longer to raise the vehicle.
High-lift jack: These are required for off-road vehicles, or any vehicle that needs to be lifted way up high to get the wheels off the ground. This jack consists of a long beam with series of holes along its length, with a small plate on the bottom and a lifting point and ratchet system that extends the length of the beam. These jacks are great for high clearance vehicles but are very long, heavy and can be unstable. Extra care is needed when using them.
Hydraulic: Uses an oil-filled hydraulic cylinder to lift. Oil is forced inside a compartment and the pressure causes the cylinder to rise. To release the cylinder, the oil disperses back into the reservoir. These jacks have quick release mechanisms so a car can be released to the ground at a quick and controlled speed.
Bottle jacks: A very popular and versatile jack because it utilises an easy, straight up and down pump action hydraulic system. The downside with the bottle jack is that it is often too tall to fit under small vehicles. If your vehicle has enough ground clearance, this little jack is a winner.
Floor jacks: These jacks are large, flat and roll on wheels. They have a large bar to pump the oil and are used by most mechanics because of the ease of use. They offer good ground clearance and after just a few pumps on that bar, the car is up. They come in various sizes but the downside to them is their size and weight. It’s impractical to carry one of these in the car and they are best left for the professionals or to keep at home.
Electric: A scissor jack that has an electric motor which plugs into a cigarette lighter. The electric motor does the work for you but is only really suitable for small vehicles. This jack may be good for people with limited mobility.
How do I use a jack on my car?
Before you jack up a vehicle, make sure it is in a safe area, on level firm ground, the handbrake is on and the wheels (not being raised) are chocked.
There are specific jacking points for every vehicle. Refer to your owner’s manual to see where the jacking points are on your car. They are typically found behind the front wheel and in front of the rear wheel, under the sill.
If you don’t jack the vehicle at the jacking points you can cause some nasty damage. Lifting at the wrong points also increases the chances of jack slippage.
Place the jack firmly on the ground under the jacking points, raise the jack until it starts to take vehicle weight, check everything is stable and continue to raise the vehicle until it is at the required height.
Do not overextend the jack. Work within its limits and never work under a vehicle when it is raised by a jack alone.
A vehicle should be supported by car stands before you work underneath. When changing a tyre, you could use the spare wheel as a safety device by sliding it under the sill of the car, in case the jack fails.
Be extremely vigilant when using and working around jacks. They are wonderful tools, but never trust your life on them.
Keep safe, and if you have any doubts about using a jack, seek professional help.
Rachel spent her early adult life around cars, motorsport and hands-on with her own cars.
This interest moved into various careers within the Automotive industry. Joined with her passion for writing, Rachel loves putting the two together to share her experience, so we can all become AutoGuru’s.