Postby JD...... » May 31st, 2011, 2:40 pm
4WDaction.com
Recovery tips
MUD
Wherever you are in Australia, you need to be prepared for mud. Even the Outback will turn into a mud fest with a bit of rain, so it makes sense that you always have to be carrying some basic recovery gear. Mud recoveries can be a simple as putting some dead branches under your tyres to get traction, right through to using three or four recovery 4WDs in extreme circumstances.
Deep mud can be one of the toughest terrains to recover a 4WD from due to the suction created from deep mud and the sheer force required to extract a bogged vehicle. For this reason, mud recoveries can be quite technical, as you have to recover a stuck 4WD in a way that will put the least amount of force on equipment and the 4WD themselves. Get in the habit of using an equaliser strap to spread the force of the recovery between at least two recovery points when you’re stuck in mud any deeper than your diff housing. When winching, using a snatch block will also ease the force applied to your winch.
While it’s not really a recovery item as such, mud tyres are definitely worth a mention as their aggressive tread and sidewalls work wonders in sloppy terrains.
If you are planning on driving a lot of muddy tracks, it’s a good idea to hook a snatch strap up to the front or back of your vehicle with a shackle before you drive some of the deeper, muddier bog holes. There’s nothing worse than fumbling your way through deep mud trying to secure a snatch strap and dropping the shackle pin deep into the mud!
ESSENTIAL GEAR
This is what you need as an absolute minimum:
Long-handled shovel
Leather gloves
Snatch strap
2x rated bow shackles
Damper
Equaliser strap
Recovery points front and back
EXTRA GEAR
This gear is not a must, but very handy if you are serious about driving in the slop:
Mud tyres.
Tree trunk protector
Snatch block
Extra snatch strap
Winch extension strap
Recovery tracks
Electric/hand winch
TOP TIPS
Be familiar with technical recoveries, such as changing the direction of the pull and slingshot recoveries.
Use equaliser straps and snatch blocks to reduce the force created by suction. Don’t be afraid to get your hands dirty and get in there with the shovel to free your diff and tyres.
SAND
Whether you’re bogged in the sand on the beach or in one of the many Aussie deserts, the recovery principles are all the same. Even if you’re the most experienced 4WDer, if the sand is soft enough, you will get stuck at one stage or another.
When you first feel your 4WD starting to sink into soft sand, you should avoid making it worse by excessive wheel spinning. When the vehicle comes to a halt, you should stop in your tracks and try to reverse. If you can’t reverse, it’s time to start a suitable recovery procedure.
Before you start rummaging through your recovery bag, see if you can lower your tyre pressures and drive out. If you are running 18psi, try lowering them to 10– 14psi. Before you attempt to drive away with your lower pressures, dig out any excess sand from around your tyres and make sure your diff and underbody are not hung up.
If you have another vehicle with you, a snatch strap recovery will most likely be your best option. If you are serious about sand driving, carry at least two straps with you, as you will often need extra length in the strap(s) so the recovery vehicle can snatch from compact sand.
If you are solo, recovery tracks are a good option. Either the ones you buy over the shelf or the ones you make out of bits of driftwood you find on the sand. As a further alternative, you can always use a sand anchor (or turn your spare tyre into one) and winch your way out of trouble.
ESSENTIAL GEAR
This is what you need as an absolute minimum:
Long-handled shovel
Snatch strap
Leather gloves
Damper
2x rated bow shackles
Air compressor
Recovery points front and back
EXTRA GEAR
This gear is not a must, but very handy if you are serious about driving on the sand:
Extra snatch strap
Equaliser strap
Winch extension strap
Exhaust jack
Recovery tracks
Electric/hand winch
Ground anchor
TOP TIPS
Dig out as much sand from under the stuck 4WD as you can before you get into the recovery.
Don’t be afraid to drop the tyres right down to 10–14psi just until you get out.
Avoid driving below the hightide mark, so you have time on your side if you do get stuck.
ROCKS AND STEEP TERRAIN
This is the kind of terrain where a simple mistake can be the difference between putting your 4WD on its side or not. Chances are when you are driving rocks, you are putting your vehicle on all sorts of angles and no doubt have gravity against you in every case.
When you get stuck going up or down rocks, you need to secure the vehicle before you think about a suitable recovery. On extreme angles, the vehicle will want to back down the hill or off the track completely, depending on where you are driving.
Secure the vehicle by using your handbrake and footbrake together and putting the vehicle in gear, but avoid the holding the clutch in as this it will cause you to slip. If you have stalled and you can’t engage the clutch without slipping, you will need to secure the vehicle with a chain, strap or winch, before putting the vehicle into gear. After the vehicle is secure, make sure your diffs or underbody are not hung up on hidden rocks.
The trick with steep terrain recoveries is that you never want to have your 4WD on a side angle, as this is the best way to roll your pride and joy. You might have to do a series of recoveries, like changing the direction of the pull just to get your 4WD off a side angle.
Once the 4WD is secure and facing straight up or down the hill, the second stage of the recovery can commence. This might take three or four times the amount of time required to get the vehicle to safety than other recoveries, but is not worth rushing due to the technical nature and safety elements of rock recoveries.
ESSENTIAL GEAR
This is what you need as an absolute minimum:
Snatch strap
Leather gloves
Damper
2x rated bow shackles
Recovery points front
and back
Chain
EXTRA GEAR
This gear is not a must, but very handy if you are serious about rock hopping:
Extra snatch strap
Equaliser strap
Winch extension strap
Electric
High-lift jack
Tree trunk protector
Snatch block
TOP TIPS
Secure the vehicle first. Recovery the 4WD so it is facing straight ahead and not precariously positioned on a side slope.
Pack rocks wherever you can to put less stress on the recovery process.
HI-LIFT JACK
An ages-old tool that’s been a staple piece of equipment in serious 4WDer’s kits for decades, the hi-lift jack is as versatile as it is useful. Its only shortcomings are its bulky nature, and the fact that hi-lifts arten’t suited to use with vehicles without barwork all around. Arguably one of the most dangerous recovery items of all, it should be treated with the utmost respect.
6 STEPS TO A BASIC HI-LIFT JACK RECOVERY
1. Recovering yourself with a hi-lift jack involves lifting the vehicle high enough so that the wheels come off the ground and you can place rocks, logs or other objects under them. Work with the wheels that are dropped right down at the bottom of their suspension travel, because they’re the ones that will benefit the most from wheel-packing.
2. Select a suitable point of the vehicle that you can use to jack up under. It needs to be solid steel, because the weight of the vehicle will be sitting down on it. It also must be as flat as possible to prevent the jack sliding off sideways.
3. Prepare the ground where the foot of the jack will sit. It needs to also be as flat as possible – this may require getting the shovel out and digging out a small trench, or using hardwood as a base plate. Skip this step at your peril. Ensure that the jack is as close to upright as possible.
4. Use the handle of the jack to pull the ratchet mechanism and right up under the jacking point. The ratchet should click the whole way up, and stay in place – if not, you need to engage the locking lever on one side of the ratchet.
5. Move the handle through its full arc to start raising the vehicle. Once the tyre is a foot off the ground, pack the space by throwing large rocks under the tyres – being careful never to get under the vehicle, and always having someone hold the hi-lift.
6. To lower the jack, the locking lever needs to be flicked up, and this can be quite difficult when there’s a load on the jaw. Lower the vehicle the opposite way you raised it, by moving the arm through its full arc, and be careful when it clicks through the mechanism at the bottom of its travel, because it will want to spring up quickly.
SAFETY NOTES
As we mentioned before, a hi-lift jack is potentially one of the most dangerous pieces of recovery gear you can ever use. The inherent problem is with its instability. It gives you the ability to jack the end of a vehicle a couple of feet off the ground, with no lateral support. Only ever use a hi-lift for recovery purposes, as they’re not suited to changing tyres or doing servicing. Never get under a vehicle supported only by any jack, let alone a hi-lift.
ADVANCED TIPS AND TRICKS
Find yourself stuck fast, where no amount of work with the jack will free you? If you have a few bits of gear, you can turn your hi-lift into a hand winch. It’ll be damned slow going, but it’ll get you moving again.
The way to do this is to get hold of a product called a Jackmate, which is an adapter that bolts to the top of your hi-lift jack. This adapter is rated to accept a shackle and chain, which you use to secure the jack to an anchor point such as a tree. A strap from your vehicle, secured to the jaw of the hi-lift (lying sideways, in line with the recovery strap) will then drag the vehicle forwards as you move the handle through its arc. As we said, it’ll be a slow and hard process, but with a bit of work your vehicle will be pulled free.
TOP TIPS
Keep your hi-lift cleaned and greased, and out of the elements if possible. A cover bag will ensure it works the next time you need to use it.
Don’t be tempted to try jacking up under soft plastic mouldings or thin panels because you’ll only damage your vehicle.
A large metal or wooden plate as a base will spread the load of the jack across a larger surface, preventing it from sinking into soft ground.
SNATCH BLOCKS
Ever wondered about the physics behind a snatch block’s operation? Here’s how they work.
The forces generated during a recovery depend on the vehicle’s weight, its rolling resistance, and the gradient of the obstacle you’re clearing. For this example, let’s say there’s a total resistance of 3500kg placed on the winch. A single-line pull in this scenario will require 3500kg of force to be exerted by the winch. In a recovery situation, there’ll always be other factors that come into play, so the exact physics equation doesn’t quite apply.
However, we can still average out a ratio to explain what happens. For this single-line pull we give it the ratio of 3500:1 – ‘3500’ is the mass, ‘1’ is number of lines in the winching pull, and therefore the time taken to winch that distance.
When you add a snatch block, the length of rope required is doubled. That means our ratio then becomes 3500:2, which is divided down to 1750:1. The winch now only has to pull 1750kg, instead of the initial 3500kg. The only downside here is that because you’re doubling the length of cable required, you half the speed at which the stuck vehicle can be moved forwards because you’re doubling the amount of winch rope needing to be spooled in.
By adding a second snatch block and running the cable back out to a tree, the ratio then becomes 3500:3, or 1167kg – a third of the initial resistance.
There is another factor in the equation, and that’s the reduction of effect proportional to the angle of the two cables running through the block. At 90° to each other – ie, the cable going in one direction and coming out at a right angle – the effect is halved. That’s true all the way up until the two ends are at 180° to each other – essentially a single-line pull, with the snatch block hanging uselessly.
ELECTRIC WINCHES
7 STEPS TO A BASIC WINCH RECOVERY
There’s a reason why electric winches are so popular. They’re easy to use, can extract most vehicles from most situations, and require very little physical exertion in their operation. But they can also bite back – hard – if not used properly.
1. Disengage the winch’s free-spool mechanism, and spool out an appropriate length of cable. You should have the engine running, with the handbrake and footbrakes applied. Always have someone at the vehicle controls to secure it in case of equipment failure.
2. Select a proper anchor point. This typically will be either another vehicle, or a tree. If it’s a tree, ensure that it’s at least 2ft across in diameter, and that it’s not broken, damaged or loose in the ground. If it’s a vehicle, look to secure it to a tree to prevent it from moving when under load.
3. Use a tree trunk protector and a shackle to form an anchor point around the tree. Attach the cable, re-engage the winch’s free spool, and take up the majority of the slack by winding the winch cable in until it’s nearly taut.
4. Attach a suitably heavy blanket, jacket or recovery bag across the winch cable/rope, to act as an air brake and catch the recoil of the cable in the event that it lets go. 9 out of 10 breaks will happen near the hook end of the cable, so keep the damper up in the front one third of the line, stopping to readjust as necessary.
5. Take up the slack in the line so that the front suspension is loaded up. Select low-range, and first gear for both manuals and autos.
6. Spool the winch in, and assist by feathering the accelerator or clutch just enough to keep up with the speed that the vehicle is being pulled forwards. Do not overrun the winch so that the cable goes slack. Keep the steering wheels pointed parallel with the winch cable.
7. Winch in periods of 30 seconds on, 60 seconds off to ensure that you don’t overheat the winch. Repeat this process until the stuck vehicle is freed, stopping to re-position the cable damper as necessary.
ADDITIONAL GEAR YOU’LL NEED:
Tree trunk protector
Rated shackles
Air bracket – recovery bag/blanket/heavy jacket
Gloves
Snatch block
Rated recovery point(s)
SAFETY NOTES
The massive amount of force that an electric winch can muster is a recipe for pain if it all turns pear-shaped. If you find that your vehicle is going nowhere fast, regardless of how much you spool the winch in, stop and reassess the situation.
Feed the winch out just enough to take most of the tension out of the rope, still leaving enough to support the vehicle without it rolling. While a winch is a great tool, it’s not the be-all and end-all of recovery items. Use your common sense, and a shovel, rocks and whatever else you can find, to aid in building an escape route. The less force you need to use, the safer your recovery will be – and the longer your winch will last!
Winch ropes go off like a shot when they let go. All that force that was trying to pull your vehicle forward, then translates into a whip that has the ability to take off a leg. Keep all bystanders right away from the recovery process at a minimum of 150% (one and a half times) of the length of the cable’s length. Kids especially!
While driving with the winch is a great way to assist it and reduce load, it’s all too easy to get excited and over-drive the cable so that there’s excess slack. In the event that the vehicle rolls back, the take-up of the slack will shock load the winch, and put the entire weight of the vehicle through every component from the shackle on the cable damper to the bolts holding the winch to the bar.
Remember to always wear gloves when handling wire cable, and keep your hands well clear of the fairleads.
ADVANCED TIPS AND TRICKS
It’s rare than anyone ever chooses to get stuck in the perfect position. If your winch cable isn’t long enough, use a winch extension strap to attach it to the anchor point. Don’t ever spool the cable right out to its end. Winches need a minimum of at least six wraps of cable around the drum to maintain maximum strength.
If you’re seriously stuck, and the vehicle’s going nowhere because the winch is running out of oomph, then effect what’s known as a double-line pull. By adding a snatch block into the equation, where you previously had your tree trunk protector, you can double the line back to the vehicle and attach the winch hook to a suitable front recovery point.
By spreading the load across two anchor points (the tree, and then back to the vehicle itself), you’re halving the load on the winch and doubling its pulling power. Still struggling? Add another snatch block to the line, anchored to the front of your vehicle, and run the winch cable out to a tree trunk protector for a triple-line pull.
Need to recover another vehicle, but can’t get in a straight line to winch it? Use the same process as a double-line pull, introducing a snatch block into the equation. The only difference is that instead of running the cable back to your own vehicle, you can use the block, anchored off a suitable tree, to change the direction of the line pull. Just remember to properly secure your own vehicle fi rst, or you’ll risk moving your vehicle instead of the stuck one.
Ever been in a situation where the vehicle in front is stuck, but you’re behind it with the winch? If the track’s too narrow to drive around the stuck vehicle and turning around isn’t an option, a slingshot winch is what’s required. Again, this uses the same principles as a double-line pull, utilising a snatch block.
Select a suitable tree as an anchor point in front of the stranded vehicle, and manoeuvre the winch vehicle as far as possible over to that side of the track. Run the winch cable up past the stranded vehicle, through a snatch block attached to the tree with a tree trunk protector, and back down to a proper recovery point on the front of the stuck vehicle.
Here’s the important bit – you’ll need to then anchor the rear of the winch vehicle somehow. It could be against another vehicle behind it, or a decent-sized tree if there’s another tree trunk protector available. This is vital, otherwise you’ll find that the winch vehicle, with less inertia against it than the stuck vehicle, will move forward first.
TOP TIPS
Service your winch properly at least every 12 months.
Winches draw huge amounts of current. Always keep the engine running wherever possible.
Never run a winch cable around a bare tree. Use a tree trunk protector and a rated shackle.
Stall recovery:
While going up hill and loosing momentum allow the vehicle to stall in gear, as this happens apply brake. Make sure the rear of the vehicle is clear as you prepare to reverse down the hill.
Place the vehicle into reverse and on the lowest 4WD gear, take your foot off of the clutch and slowly off of the brake/ disengage hand brake, when you are ready keep your feet by the seat (off of the pedals) and start the vehicle so that it is jump started in reverse and it rolls down the hill under control
SNATCH STRAPS
A snatch strap is more than just a heavy-duty tow strap. It is designed to be elastic to a degree, and stretch up to 20% of its length under load. The practical upshot of this is that during a snatch recovery, the effort of the tow vehicle moving forwards transfers through the strap’s length at full stretch. This results in a short but intense rebound effect that is concentrated on the stuck vehicle’s recovery point, which all going well should free the vehicle.
The large amount of force involved in a snatch recovery again brings with it dangers, which is why it’s essential to use a snatch strap correctly.
5 STEPS TO A BASIC SNATCH RECOVERY
1. Use a long-handled shovel to reduce the load clear as much of a path as possible in the direction that the stuck vehicle will be recovered.
2. Position the recovering vehicle approximately 75% of the length of the snatch strap away from the front of the stuck vehicle, allowing for 2-3m of slack in the strap. Connect one end of the snatch strap to a rated recovery point on the front of the stuck vehicle, using a rated shackle if required.
3. Untangle the rest of the strap, taking care to remove all of the twists. Attach the remaining end to the rear of the recovering vehicle, and lay the excess slack in the strap out to the driver’s side of both vehicles, visible by both drivers. In an ideal situation, two air dampers should be used – one on each end one-third of the strap.
4. All bystanders should be moved out of the way, with one person on a hand-held UHF co-ordinating the recovery. Once both drivers are ready, the tow vehicle should take off in first-gear low-range.
5. Using the take-up of the slack as an indication, the driver of the stuck vehicle should start driving just as the strap goes tight. This will assist the tow vehicle by scrabbling for any available traction. If done correctly, this should free the vehicle. If it doesn’t, rethink the situation and go back to step one as necessary.
ADDITIONAL GEAR YOU’LL NEED:
Shackles
Rated recovery point(s)
Air damper
SAFETY NOTES
Dirty, worn or damaged snatch straps are compromised in their strength. How compromised? Try a scary 25% less strength for an old muddy strap, 20% for a wet, salty one that’s been used at the beach, and a phenomenal 45% for one with a knot in it.
Snatch straps have wear indicators; threads that pull out of the stitching to indicate when a strap has lost its strength. For the price of a new one, it’s just not worth the risk.
Force equals Mass times Acceleration. We can’t alter the mass of the recovery vehicle, but we can limit the acceleration. Ensure that only a maximum of 2-3m of slack is left before a recovery. If it doesn’t work the fi rst time, go back to the shovel before backing up further.
ADVANCED TIPS AND TRICKS
Can’t get close enough to the stuck vehicle to get a strap onto it? Connect two snatch straps together by passing the loop of one through the second, then feeding the entire of the second strap back through the loop of the first. Use a rolled up magazine to prevent it coming back out again. This is a much safer practice than using a shackle to connect straps, which can turn into a missile if something lets go.
Cases of hard snatch recoveries literally twisting chassis aren’t unheard of. The use of an equaliser strap – literally, a strap that attaches to a recovery point on each chassis rail to equalise the load across both points – is a simple and effective way of preventing damage to your vehicle.
TOP TIPS
Don’t use a winch extension strap as a snatch strap. They don’t have any stretch built into them.
Clean dirty straps with fresh water as soon as possible and allow to drip-dry out of the sun.
Inspect your straps regularly for signs of deterioration and replace as necessary.