4x4 Jacking & Snatch Recovery
CAUTION - Never get under any vehicle that is only supported by a jack.
By far, the best jack for four wheel drives is the Hi-lift type. It can lift virtually any vehicle and, with the aid of chains, it can be used as a winch.
The standard jack supplied with most four wheel drives can only raise the vehicle sufficiently to change a tire on paved roads or hard packed surfaces when the vehicle is not bogged. They usually rely on placing the jack under the vehicle in special spot on the frame or unibody. If you try using this type when you are bogged to the chassis in sand or mud you'll understand why it's quite inadequate. The Hi-lift type jack can be used on any suitable part of the vehicle and can lift a larger amount of weight much higher than the standard jacks.
Some vehicles do not have suitable points to use a high lift jack due to the curved nature of their bodies and their bumpers. There are several types of jack adapters available to overcome this limitation. Hi-Lift makes an adapter that attaches to the lip of the underside if the curved bumpers. An adapter is also made that works well with the ARB Bull Bars.
It is best to have a jack plate around 300mm x 300mm when jacking on sand or mud to stop the jack burying itself. 7 ply plywood or 3.5mm steel is ideal, or if you carry a barbecue plate, this may be suitable. To test your jack plate, place 2 bricks 200mm apart with the jack plate on top, Slowly jack the vehicle while observing the plate. If it survives this without distortion it should be suitable.
A Hi-lift can be used as a jack with the aid of suitable chains. The top of the jack is attached with a chain to a suitable anchor point while another length of chain is attached to the bogged vehicle. On the bottom end of the jack is attached a length of chain with a clevis hook, while on the moving leg of the jack is attached a chain with a clevis claw.
This allows the jack to pull the vehicle approximately one metre and then attach the clevis hook while lowering the jack. The clevis hook stops the vehicle from moving back as the jack leg is lowered, ready to move the vehicle one metre again. This process is repeated until the vehicle is free.
Exhaust Bag Jack
The exhaust powered bag type of jack is very simple and easy to use, provided it can be placed under part of the vehicle. It is quite effective, especially in sand where, if necessary, a small area can be dug away to accommodate it. It requires the vehicles exhaust system to be in good condition as even a small hole will prevent the bag from inflating. It can also cause rusted or weak areas in exhaust systems to blow out.
Be sure when placing the bag under the vehicle that sharp objects are clear from the bag to avoid puncture. Once in position, connect the pipe to the vehicle exhaust and start the engine (in neutral). When the wheel is clear stop the engine and simply fill in the hole or rut with whatever is available or dig away any sand that has built up.
Jacking to recover a vehicle is usually done to get a wheel out of a rut when a vehicle is "hung up", or to fill in wheel holes in dirt and sand. It allows any available material to be placed under the wheels of the bogged vehicle to either provide traction or build up a rut to enable the vehicle to drive out. Furthermore, it can be used to "break suction" in mud when snatching or winching is not working.
Additionally, by jacking up the entire end of a vehicle with the Hi-lift jack, for example on the tongue of the tow package, the vehicle can then be pushed sideways to allow it to be move out of a rut or soft section. This procedure must be performed with no bystanders near the jack in case it springs out.
- Jack the vehicle in the middle of either end until both wheels are clear of the ground by at least 300mm.
- Clear everyone from the jack end of the vehicle and position yourself with the vehicle between you and the jack so that it cannot spring out and strike you. Be aware of where the jack may end up and ensure it won't contact any part of the vehicle when it moves.
- Proceed to push the jacked end until it topples off the jack. This procedure can be repeated at both ends of the vehicle to "walk" it sideways.
This procedure has inherent dangers as the vehicle is very unstable with two wheels off the ground. All bystanders should be well clear of the vehicle and the person operating the jack should be aware that it may "pop out" unexpectedly.
What is a Snatch Recovery?
- A Snatch recovery is where a bogged vehicle is recovered by using a mobile vehicle to pull the stuck vehicle free.
- A Snatch recovery differs from a normal tow recovery because the line connecting the two vehicles is not tensioned prior to the recovery as in a tow recovery.
- A Snatch recovery relies on the elastic properties of the strap to work properly. During a normal snatch recovery, the strap will elongate by around one metre.
- A Snatch Strap is a nylon-webbing strap approximately 9m in length and 75mm wide with eyelets at both ends. It has a typical breaking strain in the order of 9,000kg for a standard snatch strap. It pays to look after your snatch strap as a nick of only 1cm can reduce its breaking strain by over 50%.
The snatch recovery technique requires a second mobile vehicle and a snatch strap to perform the "snatch".
The mobile vehicle is positioned to allow around 2m of slack in the snatch strap, while avoiding getting bogged as well. The direction of both vehicles should be lined up as straight as possible and the strap should not be twisted.
Hook the strap to a suitable vehicle tow point using shackles rated to at least 3.25 tons.
CAUTION - Never place a Snatch strap over a towball.