Measuring real world 4x4 recovery force

[@GavinEarnshaw]

Nice work mate. Thank you. Glad you mentioned digging out. The best way to think is that the tyres have to rise up the distance to flatter ground so you are lifting the entire weight up before you can move. Hence why bogged below centre of wheel doubles the recovery force. The guy who died last year in the US from a botched snatch recovery had spun tyres and dug down making the recovery much harder. ETA: one inch of vertical is enough. From ex UK Royal Engineer, recovery specialist who I had at our 4x4 site a few years back.

[@L2SFBC]

what do you mean by one inch of vertical?

[@jasonunsworth7775]

Heavy winching always makes me think about what is going to break on the vehicle first, not whether I have enough force to shift it. And not the obvious things like recovery points. Steering, suspension components, even tyres and rims. I’ve had light trucks bogged to the chassis that have taken heavy forestry plant to lift rather than drag out. Huge forces.

[@GavinEarnshaw]

@@L2SFBC his comment was that you have to lift the entire vehicle up that 1 inch before you start to reduce the effective slope. So the same slope angle calcs apply even if it is only 1 inch lip. Obviously with soft ground then that may give way as you pull. (Didn't you mention the extra pull on your ute when you had it on that 22⁰ slope?)

[@SuperchargedSupercharged]

Made me smile, I remember almost 40 years ago when that diagram with the truck and tank were shown to me.

[@georgecarousos6735]

Excellent content and info Robert. The load cell does not lie. I can't believe how many times I've seen people try to winch a vehicle over a major obstacle without using even the most minimal ramping system available to them (Maxtrax, rocks, dirt, etc). Your demo at 11:12 of the video is a perfect example of drastically minimizing the line pull just by using some ramps. I've never found a downside to using a double line pull either, only upsides. It only takes a little more time and work, but the results are worth it.

[@trickster8635]

Army taught me assume 100% vehicle mass for 45 degree and beyond. Don't for get to add in 20% safety factor to calculating load/resistance. Any damage incurred when entering the mire, add another 20%. (this could be as simple as a tyre rolled off the bead or a bent wishbone etc.) Don't dismiss the 45 degree slope out of hand. Always consider that a vehicle bogged in a deep depression has to be pulled up the embankment, often a very steep one at that. You would be calculating the following - vehicle mass, rolling resistance (mud), gradient,(ie the slope out of the hole), ground resistance if pushing mire ahead of the vehicle, damage and of course a safety factor. Does all of this exceed the weakest point of your tackle layout? Can you reduce the load on anchorage by incorporating additional anchors? Then we get into loads on deadman anchors and tree's etc, that is a whole other chart for what size tree will resist a given load. From an ex RAEME recovery mechanic.

[@L2SFBC]

Thanks good rules of thumb!

[@IsraelUsman1]

Thanks for this. It is literally the best winching tutorial I've seen. Very educating and in very easy-to-understand terms in spite of the technical details. Hope in the next video you continue emphasis on safety. I've seen too many videos with people standing too close to a loaded winch cable, and instances where people are not wearing any protective gloves. Thanks again. This is a great video

[@cameronwood1994]

Firstly, I take it back what I said on Facebook about winching and driving. I've learned something here which I didn't know before. Secondly, it now makes sense why Land Rover's 1980's book Winching in Safety states that a double line pull should be used if your winching calculations estimate a line pull greater than 2,268 kg (5,000 lb), noting that the factory-approved winches back then typically had a rated line pull of 3,629 kg (8,000 lb) - Superwinch Husky, Warn M8274, Warn M8000 etc. - to the point Land Rover didn't authorise single-line pulls greater than 2,268 kg (5,000 lb) in that book. I will add though that the British Army's Royal Electrical Mechanical Engineers (REME) Recovery Manual does mention two additional factors to be taken into account regarding recovery forces. Firstly, if half of the wheels are damaged, you need to add the weight of the vehicle as rolling resistance, with all wheels damaged being twice the weight of the vehicle. Secondly, it states that you should add a safety factor of 25% of your total sum of resistance to your calculations, which based on what you have shown seems like very sound practice.

[@L2SFBC]

Yes, should have mentioned both those points thanks.

[@v26224]

a great video. the only time i have used a 4:1 compound mechanical advantage was when i had to use my Sierra to recover a bogged cruiser. main reason was due to the little zuke not having enough resistance to hold itself, so by putting 3/4 of the recovery load onto a static anchor i was able to pull the significantly heavier vehicle out.

[@erictyrrell3560]

Wonder if a short section of kinetic rope would help dampen those tension spikes, and if doing so would be beneficial and safe..

[@L2SFBC]

We plan to try that at some point.

[@marcushiam6940]

Going by the REME and RAEME recovery manuals what you have called the "Mire" factor is actually a factor of slope and rolling resistance. For example, a vehicle bogged to the axles would in effect have its wheels facing a 45 degree slope so a bit of elbow grease with a shovel will reduce that factor (as per your sand example). Then the rolling resistance of that surface comes into play as well. One thing that's not generally acknowledged or taken into account is damage factors, ie broken steering arms, damaged suspension and flat tyres. I'll go along with pretty much everything you've said but the best recovery technique involves taking 10 minutes to assess the problem, work out how you can improve physically improve the recovery process -Shovel, Change tyre, straighten steering, chop off stumps the vehicle might be hooked on etc. Learn your primary machines and how to apply them. I can't count how many vehicles I've driven out of bogs in mud and sand by digging and reducing tyre pressures rather than running for a snatch strap or using a winch. To me a winch is a desperate last resort, not a go-to for recoveries.

[@L2SFBC]

Yep every manual has a different take but same principle

[@LesNewell]

In my experience you generally need less pull than you'd think. I use a 4500lb winch on my Jimny and it's always got me out. Sometimes I have needed to double line pull. I chose such a small winch because of the weight. I can easily carry the winch in one hand. This is important for me because it is removable and I have receiver mounts on each corner of the car. This gives a huge variety of possible pulling configurations.

[@L2SFBC]

4500lb = 2000kg so that's about the same as a 10,000lb for a bigger 4x4. Also, we can recover vehicles using hi-lift jacks and hand winches...so I agree, giant winches are always necessary.

[@060racing8]

I have a 4500lb winch on my Subaru. I went with this as it should be enough on paper. However, although in most scenarios, it is fine in the hardest conditions, even doing double line pulls, it struggles although I did this to save weight and not affect weight distribution much I would consider going to a bigger winch as breaking a winch line on a steep Hill is downright scary. This was on a 43° hill

[@LesNewell]

@@060racing8 I have to admit I was a little concerned about that myself. I fitted the next size up synthetic rope to give some overhead. All of the rest of my rigging is stronger still. The biggest problem I find with this winch is the small amount of line that fits on it. It means I have to carry a fair amount of extra line with me for rigging.

[@060racing8]

@@LesNewell and it's probably not a good idea to be winching a Subaru up a hill climb made for motorbikes

[@LesNewell]

Probably not but we've all done things that looked like a good idea at the time. I have to admit these days unless I am at an off road event I only use the winch to get myself back out, rather than trying to winch further into trouble.

[@squatch2461]

Great video and info, as always. As far as driving a winch: When on a slope/grade, imho, the biggest issue is if the driver uses too much throttle, puts slack in the winch line, then loses traction and slides back applying a sudden jerk to the winching system. I'm all in favor of driving a winch when appropriate, as I believe you said. Too many what ifs to address them all. 🍻

[@morgenwoanders]

Again: best information you can get on KZbin. Thanks!

[@michaelblock3998]

Reduce the mire factor! Cheap and easy step to recovery.

[@franciscocunhaetavora9132]

Winches have a secret specification that no one talks about: gearing. You will find that within the same range of a manufacturer's winches, all have the same motor with the same power, but with different gearing to give different load ratings.

[@zen6zen]

When I saw Jimny with 12000lbs winch I was laughing a lot - that just stupid. Excess weight on from bumper is affecting driving safety. I bought 4500lbs for mine Jimny and it still has plenty of power.

[@bluesideup007]

Excellent presentation. But, no mention of loads in snow. Where I live this would be the most likely scenario. Not uncommon to be bogged down up to the axle (or more). And, I suppose the density of the snow would be a factor as well.

[@L2SFBC]

I've not seen stats for snow, and not measured it myself when I've been bogged. I would use the mud/mire figures if soft snow as that parts nicely and doesn't suction, but if it's more icy, then could even be above mud. As you'd know, snow could be a loss of traction more than anything else, icy, or the snow up to the headlights in which case you're pulling through it.

[@243WW]

Mate some great info as usual Rob!!! Very grateful for your efforts.

[@JulietHotelFoxtrot]

This is an outstanding video. Thank you. Really interesting, and very helpful.

[@L2SFBC]

Thanks please share!

[@nealesmith1873]

Great information! I have a copy of the US military recovery manual...amazing book!

[@ianmac2963]

THANK YOU ... SUPERB video and INFO I CAN USE !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[@L2SFBC]

Glad it was helpful! Please share!

[@salihabdullaharik]

Great technical data. Thank you so much👌

[@L2SFBC]

Glad it was helpful! Please share :-)

[@markh6676]

Excellent presentation.

[@ckaparos]

Very informative

[@malachi2371]

Really helpful, outstanding work! Thank you!

[@spitfire1two]

Fantastic video! Question for the class: when we say the force required by slope, is the force considering a hard pack surface or is the calculation void of friction with the surface? In other words, if asphalt requires a force of 10% the vehicles weight, and a 15 degree grade requires roughly 25% of the vehicle’s weight, would the actual calculation be 35% of the vehicles weight, or does the 25% for grace already consider being on asphalt?

[@L2SFBC]

The gradient force is worked out assuming no rolling resistance at all. Then you work out the rolling resistance and add it. So 35 total.

[@spitfire1two]

@@L2SFBCunderstood- assumed as much. Thank you so much for all the amazing info!

[@spitfire1two]

@@L2SFBCahhhh and now that I’m rewatching, you talk about that point specifically. A couple times 🤦‍♂️ forgive me for that!

[@L2SFBC]

That's ok, most people watch my videos 2-3 times to get everything, I know I said that but I don't like to throw that in people's faces :-)

[@sassanlachini5383]

Danke!

[@L2SFBC]

Thanks so much for the Super Thanks!

[@joeking3339]

I have a JK Rubicon ,,, Auto ,,, do you always recommend using Auto in neutral rather in Park for assisted winching ?

[@alanpickering1504]

Hi Robert Enjoyed the video and looking forward to the follow ups. My vehicle is an Isuzu MU-X with little lift and therefore getting beached or pancaked in ruts like you demonstrated is a very real possibility for me. If (probably when), in that situation I did think I would lift the rear of vehicle up with the exhaust jack and insert the TREDS I carry under the rear wheels to get the lift. However, thinking about this as I type, I'm realising the vehicle would most probably roll down the hill, tumbling over the balloon of the exhaust jack. Hmm! The bottle jack I carry could possibly suffer a similar fate and topple. Instead of a winch, I've plumped for a pair of BOG OUTS. So I suppose I could fix and fully tension the BOG OUTS to the front wheels, before using the exhaust jack under the spare tyre to lift the rear wheels sufficient to place the recovery boards under the rear wheel and then maybe lift the front wheels with the exhaust jack to get the second pair of recovery boards under the front wheels, still with the BOG OUTS under tension Bitter experience tells me that placing recovery boards under slack BOG OUTS only results in torn BOG OUTS. Alternatively, rather than trying to place recovery boards under the front wheels, simply skull drag the front bash plates over the centre hump and use the four recovery boards I have on the rear wheels, alternately shifting them along the ruts as the car progresses up the slope. What do you think? PS: Found the tip about not using power on greasy side slopes particularly useful.

[@L2SFBC]

You can winch-drag a 4x4 across earth. I did in this video, you saw how hung up I was. So no need for that lifting unless there is a large rock in the way or something. Bog Outs are good but remember unless you have a locker you need them on both wheels. Place your boards as required, maybe even all 4 under one wheel, to maximise clearance & traction.

[@alanpickering1504]

Wow! You're quick on the replies - so good. Thanks so much for the advice and yes, I only use BOG OUTS in pairs.

[@elcapitan3300]

Excellent informative video.

[@L2SFBC]

Glad it was helpful! Please share!

[@jasonfranklin7549]

Very interesting and informative,some time ago i seen a dvd of a certain group of 4wders from a well know in its day magazine,they had a heavy 4wd badly bogged in beach sand,the vehicle had actually gone under water so was a dead vehicle,they hooked up three winches on single line pulls from three recovery vehicles and proceeded to winch it out with great effort,my guestion is is there any point in doing this,would the three winches be sharing the load or would they have been better to use one winch and pulley blocks to get a mechanical advantage?

[@L2SFBC]

The triple-line pull loses power to friction. Three single lines would not. Also, there are then three handy anchor points not one.

[@operation4wheelz]

Would interesting to see the loads when in boggy terrain. Driving/not driving… eg those situations where driving tends to dig. I’m actually planning on going back to a 9500lbs winch. 1. Because the brand I’ve chosen saves me 10kgs 2. 12000 is unnecessary slow. 3. I want my winch to be the weakest link in the system.

[@L2SFBC]

Also a touch lighter. And for a Wrangler...12k isn't necessary. I'll do boggy when I get a chance.

[@operation4wheelz]

@@L2SFBC definitely not necessary. When I purchased it, my theory was less need for double line pulls. But I think in terms of speed and versatility, 9500 is better anyway. Can go to a double line or a compound pull and it not be too slow.

[@L2SFBC]

A double line in theory halves the speed, but in practice, given electric motors slow down under load, then the actual difference is much less than half as the double-line about halves the load on the motor.

[@operation4wheelz]

@@L2SFBC 💯

[@tailgatecampers6068]

J😢​@@L2SFBC

[@pauldavies4650]

Aqesome vid 👌

[@tedstephenson7116]

Does the diameter of the snatch block roller effect the wench power required for a pull ?

[@marcushiam6940]

Good question. The recommended minimum size for a snatch block pulley wheel is 10X the diameter of the rope used, more to protect the rope from excessive bending which can open up the lay of the rope and ruin it. Not so much of a problem with dyneema ropes which are Hawser Laid ropes whereas Steel Wire Rope is typically Ordinary lay in its construction.

[@marekmaecki4362]

- 102%🤔🤭

[@Monty_NSW]

slow down please...you can speak faster thanI can process :)

[@L2SFBC]

Run the video slower, maybe that'll help?

[@Monty_NSW]

perhaps the communicator and journalist might trim the enthusiasm down 3db