The high-lift jack is one of the most useful off-road tools available, an indispensable and highly versatile device but can only be used if a strong vehicle jacking platform is available. Working four-wheel drive vehicles should have adequate bumpers for this, but unfortunately most modern 4X4s do not. Rear tow bars make good jacking points but on the front end of most vehicles there is nowhere to use the jack. The cure is simple: have your off-road equipment outlet fit them for you. Armed with a spade and a high-lift jack, in most cases, you are better equipped for the unexpected than a vehicle equipped with a spade and a winch.
The original American-made Hi-Lift has proved itself time and time again to be the best. In most cases high-lift jacks are carried on the outside of the vehicle and dust clings to the oily lifting mechanism, which causes the mechanism to jam. Q-20 or a similar spray lubricant must be used to free the mechanism before it is used. But take care: this can cause the formation of a mixture of dust and oil – a grinding paste which quickly wears the components. The only way to prevent this is for the jack to wear a jack-nappy when in transit.
These are large polyurethane bags placed under the vehicle and inflated by exhaust gas to lift the vehicle so that objects which aid traction can be placed under the wheels. Balloon or air jacks have some disadvantages off-road and are not as versatile as the high-lift. They are nevertheless easy to use and do not require much physical strength to operate.
These are available in a very wide range of lifting capacities from one to 15 tons and over. Bottle jacks tend to be rather tall so before you set off on your safari, simulate a puncture by releasing the air out of one of the rear and one of the front wheels and make sure that the jack fits under the axle now that the tyre is flat. Bottle jacks must be upright to work and periodically need topping up with hydraulic fluid. To jack up a fully loaded 4×4 you will need one with at least a five-ton capacity.
Upright screw-thread and scissor jacks
These are sometimes supplied with a vehicle as standard jacking equipment. Those that resemble bottle jacks are worthwhile although a little tedious to operate. Some designs are intended to work on one specific vehicle only. The screw threads must be kept clean and well oiled to prevent jamming by dirt and dust. Unlike a hydraulic jack they function at any angle, which is useful when using the jack to straighten bent bodywork.
Scissor jacks are by and large unsuitable for off-road use, as they
jam easily as dirt clogs the threads and are unreliable and break with heavy duty use.
When using a jack, other than a balloon jack, on soft ground a plate is needed to prevent it from sinking while the vehicle is being raised. A steel or thick wooden plate approximately one foot square, preferably with lugs attached to its surface to prevent the jack from slipping sideways, is ideal. A heavy wooden laminated bread board with large wood screws to act as lugs is easy to make and works well. An even cheaper jacking plate can be made from two square 16mm pine boards. Laminate them together with a waterproof wood glue, making sure that the grains run perpendicular to each other. As a last resort the spare wheel makes a very effective, if cumbersome, jacking plate. Jacking plates such as the one illustrated are available at 4×4 stores. For me, I just take along a heavy 50cm pine plank.
When using a regular bottle jack a wood block about 45mm thick can be very useful as a jacking plate, and also for when the bottle jack is used in awkward predicaments, for example when the maximum stretch of the jack is not sufficient. It is also very useful when the bottle jack is used to aid vehicle recovery.