4WD Vehicle Recovery Techniques
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4WD Vehicle Recovery Techniques
SNATCHING The strap acts like a giant elastic band, once it reaches its maximum stretch it rapidly contracts and jerks or snatches the bogged vehicle free. Usual 9 metres in length but 17-25 metres is also useful. Made of a nylon type material and woven diagonally into a web section it not only stretches (great for absorbing shock) but in doing so it stores kinetic energy - sometimes as much as the towing power of a vehicle - in other words a vehicle can exert nearly twice as much tow power using a Snatch Strap. Snatch Straps need to be used with care - there are several 'weights' available. Dirt will cause chafing so keep it clean and dry, whilst any damage to the strap means it should be scrapped - never tie a broken strap, never run it over or use anything sharp and only use 'D' Shackles to connect it to the vehicle. Do not hang it on open tow 'hooks' as it could fly off. If you have open hooks fit the spring 'leaf' to them for safety.
Line the towing vehicle up as straight as possible with the bogged one. Uncoil the snatch strap completely removing any twists or knots and securely attach to both vehicles. Use only SWL - safe working load rated/stamped D shackles with a 3000kg capacity or more. If necessary join two snatch straps together to gain adequate distance from the boggy area. Join them by threading a loop of one through the loop of the other then feeding the first strap through its own loop to form a slip knot. Do not join snatch straps with a shackle (if something breaks it can become a lethal missile.) Bring the tow vehicle to within a few metres of the bogged one if possible. Clear all people away from the area. The towing vehicle should accelerate away gently taking up the slack – once the strap reaches maximum stretch and both vehicles driving, the bogged vehicle should become free, if not try again using more power. Once you become free you should continue driving until your reach firm ground and then stop and disconnect the snatch strap.
To use a snatch strap - attach the ends to 'approved' points on each vehicle reverse the towing vehicle back to half the strap length. On command of the driver of the 'stuck vehicle (or an appointed person in charge) - the towing vehicle should gently move off (as if there was no tow rope) and the towed driver should use engine power to assist. Should this not work, check if any obstruction to the stuck vehicle could be moved or minimised. Do not try increasing power beyond the strength of the strap. Sometimes, if the towed vehicle is held by suction and the strap can be held stretched and the stuck vehicle rocked to release the suction. Obviously care needed in case it releases suddenly. Another use for the Snatch Strap is in solo recovery, as I mentioned, you can't drive and winch on your own, but if you attach a hand winch to a strap and stretch it, you may be able to drive the vehicle out using 'stretch assist'.
Most front tow points are not in the centre of the car - use the one furthest from the towing vehicle to assist in bringing the two vehicles to a straight line. Much less power needed to pull a car straight rather than sideways - arrange the towing vehicle so that both vehicles travel straight, or if winching - a snatch block can be used to get the car round a 'corner'. A winch or tow over a crest will pull the towed vehicle downwards - place logs or spare wheels under the rope on the crest to counteract. Safety Remove all passengers and loose luggage. Keep bystanders as far away as the length of any rope, strap or cable will reach. One person to be in charge Only attach towing devices to approved points - never use bullbars, bodywork, roof racks etc. Make sure everybody involved is working to the same plan. Do no use any rope, strap or cable that is damaged. Do not take unnecessary risks or insist that another member exceed his/her ability or experience. Keep winch cables and straps in good condition, regularly check hooks and 'D' shackles. Make sure your car has proper tow points front and rear. A cable or mounting can break without warning and flail about causing obscene amounts of damage. The diagram shows two vehicles, one winching the other. The dotted lines show the area within which a broken cable could cause damage. Everyone except the two drivers must stay outside this area. WINCHING Costs can come in from $1000 - $3000. Ensure you wear your leather riggers gloves for protection. Wrap your tree trunk protector around a suitable tree that will allow a straight as possible pull. Aim to place it half a metre above the ground. Attach a winch cable to the protector with a rated D shackle. You may need to use a snatch block to halve the load on the winch. Check you winch loading recommendations and stay within the specifications. Take up the slack in the cable at the half way point to prevent it flaying around if something should break. Clear all people from the area. Begin winching. Do not attempt to drive out at this point as you could shock load the winch cable and cause a failure. If you have an electric winch, keep the engine running to avoid draining the battery. Never step over a cable that is under load. When you are back on firm ground again ease the tension off the cable and disconnect from the anchor point and pack up the recovery gear. Unwind the winch cable and try to postion the anchor point so the winch is pulling in as straight a line as possible. Remember a winch only pulls its full rated power on the first layer of wire, keeping that in mind its best to ensure that there are at least five wraps of wire around on the drum before any load is applied to the winch. Once the cable is extended, connect the cable to the winch point. Don’t kink the cable, bend it sharply or hook it back on itself. Wrap it around the anchor point using a D shackle. Do not allow the cable to be wound on to the winch loosely. Electric winches can only work for a short time before they overheat. Under a full load this may be less than 30 seconds before it needs a break to cool down. To ease the load on the winch you may need to use a snatch block to halve the work load. Filling in holes with rocks and digging out will make it easier for the winch. Ensure the cable remains taunt, select 1st gear low ratio and keep the engine revs up just above idle. Keep your wheels pointing in the right direction.
Manual Winches
These are lightweight and portable units and much cheaper than the electric models. The do require lots of man power. Keep your winch in good condition and well lubricated. They come with 20 metres of cable and a handle to power it.
Chains or wire ropes can be used to gain extra length, or to anchor a stationary winch vehicle, but do not use Snatch Straps with power winches. If the stuck vehicle is in danger of falling over - a second rope can be attached high on the uphill side and tied to a tree, but be careful that the recovery pull does not put extra strain on the side rope (adjust position and/or tension as recovery proceeds).
Ensure the winch is properly fitted to the mounting bolts and frame. Winches should be used occasionally even if you haven’t been bogged. Run the cable out, anchor it and retrieve the vehicle. If you have been in salt water makes sure the winch is washed down thoroughly and sprayed with CRC. Invest in some thick leather gloves, and D shackles which decrease the work load on the winch. A herc-alloy chain about 3 metres long fitted with a hook at each end (or with a grab hook and eye) is a useful piece of recovery equipment. Tree trunk protector straps are useful to prevent ringbarking, usually 80 mm wide and 3 metres long and rated 8-10 tonne. When you require extra length a winch extention strap is the way to go, made from 50mm wide non-stretch woven fabric and rated 4-7 tonnes, sold in 20 and 30 metre lengths.
Hi Lift Jack Not only can it be used as a jack but also a spreader for bending panels away from wheels after a ding, as a clamp, as a tyre bead breaker or as a small winch or wire strainer.
When changing a tyre using a high lift jack it is advisable to place a rock or log under vehicle for extra stability before climbing under vehicle. Keep it free of dust and regularly spray with CRC.
Air Jack or Bullbags Is a heavy duty bag of synthetic fabric which is inflated using the vehicles exhaust gas. Keep it clear of sharp objects. They are a compact unit and can be used on soft soil. Air jacks come from 1.5 tonne to over 3 tonnes. To use, place a mat under the vehicle away from hot or sharp objects. Place the jack under a flat surface but not a diff or gearbox, Run the air hose and connect it to the vehicles exhaust pipe. With the engine running the vehicle rises from the hole, allowing you to fill it and the drive out. Deflation can be sudden and without warning. Never work on a vehicle while being supported by an air jack.