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It’s a simple task, but it can be a dangerous one, too. Here’s some crucial advice…
Most of us have suffered a punctured tyre at some stage of our motoring lives. For many of us, it was the the first time we rummaged in the boot for the jack and wheel brace. For others, tinkering on their car at home (whether changing the engine oil, inspecting the CV boots for damage, making sure there are no oil leaks or changing brake pads) also required jacking up the car to access the undercarriage.
There are various types of jacks, including those sold with a vehicle and available from spares outlets. And even though South Africans generally prefer a full-size spare wheel plus jack and wheel brace, some modern cars forgo this set and are instead supplied with a puncture-repair kit and a small compressor. Cars with run-flat tyres might also skip the jack, rather suggesting that you drive to the nearest service station to have the tyre repaired or replaced.
If you do need to use a jack, though, safety should always be first and foremost on your mind, as having the car fall off the jack can result in very serious injury.
Chocks: The first important operation when changing a wheel or working under your car is to prevent the car from moving. Do this by making sure the handbrake is on and there are chocks behind the wheels. If you don’t have purpose-made chocks in your car, look around for bricks or rocks to jam against the tyres.
Axle stand: The second necessity is to have blocks or axle stands as a backup to the jack. This is not something that most motorists will own, but all those who do some degree of work on their cars should most definitely have a set. It is a vital safety feature that should ideally be used every time you jack up a car.
If you are changing brake pads and engine oil, or checking anything under your car, one thing you must never do is rely on the strength of your car jack. Whether a scissor, bottle or trolley jack, it can fail mechanically or hydraulically, tip over or sink into the ground. The only way to be safe is to use an axle stand, but even this is not foolproof and I always use two.
For a cheaper option or as a backup, use blocks of hardwood (not pine). As these axle blocks are quite bulky, even home mechanics are unlikely to cart one along in the boot of a car. If you get a puncture while driving, just make sure you don’t get underneath the car at any point.
Jacking points: Every car has four underbody areas strengthened for lifting. These are often clearly visible and pointed out with arrows. Your owner’s manual will indicate where they are if you’re still unsure.
Types of jacks
Scissor jack: This is the jack that is provided in most cars, especially smaller ones. Using a screw thread and nut to take the weight, its advantages are compact dimensions, light mass and low manufacturing cost. The disadvantage is it can take a while to change a wheel, even with a well-designed crank handle.
Trolley jack: These are heavier and not really suitable to store in your car due to mass and space. The basic trolleys can handle two tonnes, which is fine for most vehicles, as you usually lift just half the vehicle’s mass. It raises quickly and you simply have to wheel the jack underneath the vehicle, insert the handle and start jacking.
Air jack: This type is quite popular with 4×4 vehicle owners, because normal jacks aren’t effective on soft or uneven surfaces. They can be compact when deflated and require a compressor to inflate. Some use exhaust gases from the vehicle’s tailpipe.
Bottle jacks: These are also compact and not much more expensive than scissor jacks. They rely on hydraulic fluid, non-return valves and precision seals to handle the load and can be prone to leaks if poorly made or worn. Lifting is quick and easy once you locate the jacking point.
Farm jack: This is a heavy-duty, mechanical lifting device used by farmers and 4×4 vehicle owners. It is quite heavy and takes up more space than usual, so you won’t find one supplied with conventional vehicles. Maximum lifting mass is usually two to four tonnes.
Author: Peter Palm