Hi-Lift Jacks
Hi-lift jacks are nothing new. They've been around for a long time,and for a long time 4WDers have been using them to get out of sticky situations. A hi-lift jack can be used to lift a vehicle to change a tyre, to lift up and over obstacles and even as a hand winch. Even though a hi-lift is a versatile piece of recovery equipment, it does have its downfalls. With modern 4WDs, unless you have an aftermarket bar front and rear of the vehicle with hi-lift provisions, there is nowhere on the vehicle to jack from.
Hi-lift jacks can be dangerous - I can testify first hand that when you're lowering the jack and the handle slips and hits you in the mouth, it really hurts. Another downside is that hi-lifts have only a small base, so to make it safer, a larger base plate - normally apiece of metal - should to used to distribute the weight over larger surface area, especially on softer ground.
Exhaust Jacks
The younger cousin of the hi-lift is the exhaust jack. While your vehicle will need provisions to use a hi-lift, these are not needed when using an exhaust jack. An exhaust jack is basically a heavy duty balloon. The jack is placed under the vehicle in the area where it is to be raised. It has a hose that connects to the tailpipe and as the exhaust gases fill the jack it raises the vehicle(they can also be inflated with a 12V compressor). Like the hi-lift, it can be used to change a tyre or lift the vehicle out of a rut. Exhaust jack are also, in my opinion, a lot safer to use than hi-lifts, because the jack's surface area on the ground and the vehicle is a lot larger and the lifting and lowering of the vehicle is a lot more controlled.
Exhausts jacks aren't perfect either. They can be susceptible to punctures so you have to be careful of any sharp or hot objects onthe ground and under the vehicle. Although most brands claim to be puncture resistant, punctures can still happen. They are expensive compared to hi-lifts and they take up a far bit of room in an already packed 4WD.
Bottle Jacks
The jack I'm talking about here is the jack that comes with your 4WD standard. These little things won't help you get out of a rutor double as a winch - they are used purely and simply as jacks.They are made to jack up an axle so you can change a flat tyre on the side of the road. Although it only has one function, you should always take this jack will you. It can be used for a little extra support when doing those running repairs or in tandem with either ahi-lift or exhaust jack, because two jacks are better than one.
If you're in the market for a jack, there are a few things to consider. Do you have jacking points for a hi-lift? Do you have the extra room to store an exhaust jack?
When it comes down to it, either jack will be a great addition to your 4WD equipment box.
One last thing; for safety reasons, it is not wise to work under a vehicle that is only supported by a jack, so if you do it, it better be a life or death situation.
Source: Camper Trailer Australia #36