Gu recover points

[PhillipA]

Hello All,

Pardon my ignorance but on my 2001 GU wagon is the hook at the font underneath (on the rhs of the vehicle looking forward) is it a recovery for towing or just a tie down point.

And at the back of the wagon the u bolt above the tow bar and below the rear doors, is that also a towing point?

I want to get a forward towing and rear towing point.

If that u bolt looking thing at the rear is no good Supercheap and plenty of others sell the thing that slides into the tow hitch which is rated to 4500kg from memory. I wonder what the gu weighs unloaded and then fully loaded with fridges, eskys etc

I will be towing a boat which all loaded up with extra jerry cans, crab pots etc etc probably would weigh in at 1500 kg

I am about to fit a 12000 lb ridge ryder winch that was on special for $500 from super cheap so it may be better to winch with a double sling. Heading to the gulf where there is plenty of soft sand in one mongrel area.

[GQtdauto]

Both can be winched from but be wary about snatching ,a lot of people use the after market tow hitch setup designed for this and I don't know if TD has any left but he had some great ones for the front .
Never ever use the tow ball .

[mudski]

The loop on the back is not even good enough for winching. Remove it and have a look on the back of it and you will see why.

[Mc4by]

As mudski says don't use the back one.
The front one is supposed to be winchable but try finding someone willing to take the risk with the back of their vehicle.
Invest in rated points. TD supplied mine at a great price.

[PhillipA]

I am going for a pair of strong towing brackets fitted to the underneath front with high tensile steel bolts and a tow hitch attachment that slots into the towbar sleeve

Thanks I will forget those existing points and fit the above

By the way who is TD????

[mudski]

I am going for a pair of strong towing brackets fitted to the underneath front with high tensile steel bolts and a tow hitch attachment that slots into the towbar sleeve

Thanks I will forget those existing points and fit the above

By the way who is TD????

TD is a member whom we know as threedogs. He's the man for reco points.

[Mc4by]

This is one of the points I have installed on my Patrol. Courtesy of TD.
Mighty strong piece of kit.

75264

[threedogs]

Hi mate you can only fit one 12mm flat plate to the drivers side to
fit one to the left you'd need to drop the bullbar. Look at my vender
thread and see if my "tee" shaped ones will fit on the outside of your bull bar
Let me know which style would suit would not take long to get some cut and coated.
Thanks mudski

[GQtdauto]

Just goes to show you can learn something new everyday I was under the (wrong) assumption that the oem points were ok for a winch point but only if only skid type bogged , I wouldn't trust these points if down to the floor in sticky mud or sand etc .
Front have been converted and rear is only used for the trailer break away cable so must update that Toyota hook .

[MB]

Out of interest here please good folks, I’ve got Zinc Coated Metric Property Class 8.8 bolts on my aftermarket GU bullbar currently. Is that ok for bars and recovery points? Was warned away from Stainless Steel due to its sheer loading failure possibilities? https://www.hi-tensilebolt.com.au/bolt-strength-grades-and-head-markings/
EDIT: Bolts query only not planning on recovering off my bullbar :-(

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[Mike02Ti]

Out of interest here please good folks, I’ve got Zinc Coated Metric Property Class 8.8 bolts on my aftermarket GU bullbar currently. Is that ok for bars and recovery points? Was warned away from Stainless Steel due to its sheer loading failure possibilities? https://www.hi-tensilebolt.com.au/bolt-strength-grades-and-head-markings/


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As long as its a grade 8 bolt and above i dont see an issue with it. Which is what you have bought.
Going back to rigging we could not use anything less than grade 8 or above to lift / pull . Very similar characteristics for what we do in recoveries.
And your correct in staying away from stainless. Dont do it. Also dissimilar metal factors come in to screwing it in to a steel chassis.


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[MB]

Cheers Mike, appreciated mate!!


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[BillsGU]

I bought a set of front recovery points for my GU II from Ironman. The driver's side is easy to fit. The passenger side one comes with nuts attached to pieces of wire that can be inserted into holes in the chassis (to the rear of where the recovery point fits) and then fed onto bolts which will then hold the recovery point in place - without removing the bull bar or, in some cases, bending/removing a piece at the front of the chassis.

[threedogs]

Just goes to show you can learn something new everyday I was under the (wrong) assumption that the oem points were ok for a winch point but only if only skid type bogged , I wouldn't trust these points if down to the floor in sticky mud or sand etc .
Front have been converted and rear is only used for the trailer break away cable so must update that Toyota hook .

You could flat tow with them on a hwy but thats about it

[PhillipA]

Hope they are strong enough These are the specs........... Tow Point Specifications:

Made from 10mm plate Steel
Supplied with Hi Tensile Bolts and nuts
Direct bolt on to your chassis
No cutting or welding required in most cases
Sold as a pair
Option of using a Bridle strap
Powder coated Orange for Hi visibility
WLL Stamped to 5000kg

[PhillipA]

Each one 5000 Kg so if using bridle strap that should allow 10000kg. Should be plenty I don't usually reply to my own thread Doh!!

[Mike02Ti]

Just because your point is rated to 5000kg doesnt mean you can swing 5000kg off it.
Many other factors can come into play. Chassis strength and the actual condition (eg rust inside) of it being one.
Another is the other rigging gear your using like shackles , extension straps, the bolts holding the recovery point or anything else used in the recovery

Say for instance your 8000kg snatch strap is used off one 5000kg recovery point.
You connect to the bloke helping you out with a hitch reciever with a 4700kg shackle
Now on your recovery point you attach a 3200kg shackle. The whole system of rigging gear thst you have just attached is effectively rated at 3200kg as that is the weakest link. Hope this makes sense.

I have even seen recovery points put on with bog standard galvanised bolts. Bloke didnt know any different. They fit and screwed in and he used them not knowing they weren't rated for bugger all. All he said was they wont rust. So something else to check as your hooking up.

If you bridle it depending on the angle of the pull, one side of the chassis will load up more than the other if its anything other than a dead straight line pull.
Side loading may also play a factor depnding on the gear used.
Once extra angles come into play and side loading etc all these factors will reduce the SWL of the recovery. But yes a bridle should be used wherever possible on both cars , not just the one being recovered.

Its something to be very mindful of when doing these recoverys as the forces can be tremendous.


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[MB]

Personally watched an old Land Rovers cattle type bar fly seriously uphill at warp speed some 30+years ago.
Hindsight is scary from the old mans mates bush theories!
This great forum has saved mine and many’s lives from bad old habits unlearning :-)


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[Mike02Ti]

MB still not enough though as people are still getting hurt or killed by bad practices or misinformation/ misuse of the gear used. If this forum has prevented at least one injury or death from the discussions we have then collectively we have done well. But still more education needs to be done i think

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[GQtdauto]

I guess the one thing most people even me forget is that yeah the fourby might weigh 2.5 tonne but sink it down to the floor pan in a bog and that 2.5 suddenly multiplys depending on many factors .

[the evil twin]

Just because your point is rated to 5000kg doesnt mean you can swing 5000kg off it.
Many other factors can come into play. Chassis strength and the actual condition (eg rust inside) of it being one.
Another is the other rigging gear your using like shackles , extension straps, the bolts holding the recovery point or anything else used in the recovery

Say for instance your 8000kg snatch strap is used off one 5000kg recovery point.
You connect to the bloke helping you out with a hitch reciever with a 4700kg shackle
Now on your recovery point you attach a 3200kg shackle. The whole system of rigging gear thst you have just attached is effectively rated at 3200kg as that is the weakest link. Hope this makes sense.

I have even seen recovery points put on with bog standard galvanised bolts. Bloke didnt know any different. They fit and screwed in and he used them not knowing they weren't rated for bugger all. All he said was they wont rust. So something else to check as your hooking up.

If you bridle it depending on the angle of the pull, one side of the chassis will load up more than the other if its anything other than a dead straight line pull.
Side loading may also play a factor depnding on the gear used.
Once extra angles come into play and side loading etc all these factors will reduce the SWL of the recovery. But yes a bridle should be used wherever possible on both cars , not just the one being recovered.

Its something to be very mindful of when doing these recoverys as the forces can be tremendous.


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Uuuummmm ... not quite.

You are mixing ratings.
Some of those components are rated at breaking strain (BS)... (EG the snatchie)
Some are rated at Working Load (WLL)... (EG the 3.2 Shackle)

The load limit of that rig in the example isn't necessarily 3200.
As when the BS of the 3.2 WLL shackle is taken so you compare apples to apples it is at least 4 times or as much as 7 times the WLL. IE the BS of the 3.2T rated shackle is a minimum of 13 ton.
The shackle will therefore be the strongest component not the weakest

The max rating of the rig in the example is 2.5 ton to 3.5 ton depending.
Reason is the lowest rated item is the tow bar the hitch receiver is attached too so depends on that

[Mike02Ti]

Uuuummmm ... not quite.

You are mixing ratings.
Some of those components are rated at breaking strain (BS)... (EG the snatchie)
Some are rated at Working Load (WLL)... (EG the 3.2 Shackle)

The load limit of that rig in the example isn't necessarily 3200.
As when the BS of the 3.2 WLL shackle is taken so you compare apples to apples it is at least 4 times or as much as 7 times the WLL. IE the BS of the 3.2T rated shackle is a minimum of 13 ton.
The shackle will therefore be the strongest component not the weakest

The max rating of the rig in the example is 2.5 ton to 3.5 ton depending.
Reason is the lowest rated item is the tow bar the hitch receiver is attached too so depends on that

Not picking fights here , whilst you are correct in the breaking strain vs swl / wll you should never exceed the SWL of anything used. The safety factor is there for a reason.
Yes there is a safety factor that exceeds the SWL of a shackle. It does not mean you can use it up to breaking strain.

Snatch straps are totally different as they stretch. They should technically be thrown out after 8 to 25 uses due to the nature of them. Please note that figure depends on how well the strap is maintained as well as what the manufacturer recommends. They are also made to take a shock load for a very small period of time and not a constant load.
They can not be rated in the same way as a shackle or a normal soft sling or chain. This is why they have to be rated at breaking strain and not a SWL

Shackles can be used over and over again provided they are worn too much or warped / bent.

Try telling worksafe or a government body " oh i used the 3.2 t shackle over the SWL it is rated for then it let go and smacked that bloke in the head over there" and see what happens.

Any rigging job that is done (and this is exactly what you are doing in a recovery is rigging) should use the lowest rated component as the maximum weight. No matter what that component is or whether that component is rated at Breaking Strain or SWL/ WLL.

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[the evil twin]

Thats cool, gotta agree to disagree... IMHO recovery isn't rigging
Rigging is static and mostly a 'one off' operation, recovery is kinetic and often multiple steps.

As for the worksafe scenario (not that worksafe have any authority in recce applications but certainly get involved in workplace)... if a lift fails how do you explain to worksafe that 99% of riggers run a shackle up then back off a tad but the manuf states rated Shackles don't achieve WLL unless the pin is torqued down tight.

The reason a rated shackle is insisted upon in vehicle applications is to ensure component quality and not the rating per se.
Which is why shackles that are actually rated lighter than the load are specified in the towing safety chain regs.
EG the shackle stipulated under the Regs for up to 1600 Kg Load is 0.5T WLL and up to 3.5 ton load is 1.0T WLL and the various state Departments specify against Proof Load not WLL.
(QLD linky thingy but all states are the same now AFAIK) https://www.tmr.qld.gov.au/~/media/Safety/Vehicle%20standards%20and%20modifications/Loads%20and%20towing/Safe%20towing/Safe_towing_guide.pdf

4WD Recovery wise, another example I show to students is an 8,000 Kg rated snatchie and an 8,500 rated shackle... it almost takes two people to lift the shackle.

But, the bottom line IMHO is always use what you know is safe and if in doubt don't... or at least video it for Utube

[GQtdauto]

If I may stick my nose in here ,whatever you use for the rating or SWL etc as you both have pointed out and done a great job of explaining but to the layman am I right or wrong in assuming there is no way of knowing what weight your playing with if the vehicle is bogged to the floor ?
Seems to me that in my example it would be almost impossible to determine the weight and therefore the Breaking strain required , which maybe why so many recoverys end in tragedy or near miss .
For me if I can't winch I dig and I'm an expert plus at getting bogged .

[threedogs]

All Ill say is because there is no actual off road recovery equipement . We as Aussies have adopted lifting equipment to do the job
This has been thrashed to death over the years, now the consensus is to winch if thats slower tuff titties , far safer than other ways that are
available. Think it trough and you might get home in one piece without a hole in your 4x4 or worse you its not rocket surgery be safe,, better than limping for the rest of your life ,,,,eg only

[Mike02Ti]

As far as rigging onsite yes many riggers usually seat the pin then back off 1/4 turn. If used like this the rigger and/ or the site the pin would be moused so that it does not come loose. Now i do know riggers who do this as thats how they were taught etc and i agree it is wrong.
Depending on who you ask the usual reason they give for backing off is to stop the pin from binding. The shackle should be derated when used like this though and again should be moused.

As far as a safety chain on a trailer that again is different to a recovery. I do remember a time where they didnt really have much of a regulation regarding this other than it needed to be there and connected to the vehicle. I also agree that using rated shackles was to control a quality issue of what was being used in the past. Same with T grade chain now being used. Yes they asses it this way to breaking strain instead of SWL

Im hoping you mean a much larger shackle that 8.5t though cos they only weigh about 2.5kg though.
The biggest issue there is, is that there is no set guidelines or rulings other than manufacturer recommendations.

Even Nobles guide on recovery is very basic. For those who dont know Nobles is a provider of rigging gear and NATA certified tester. So basically anything to do with loads they are the people to talk to.
Link to their guide.
https://www.nobles.com.au/Admin/Public/DWSDownload.aspx?File=%2fFiles%2fFiles%2fPDF%2fGen eral+Information+Sheets%2fRecovery-Mate-Care+in+Use.pdf

GQtdauto yes there is no set calculations for you being bogged deep in mud, sand or any other way you can get stuck. Hence why these recoveries are so dangerous. Who knows if your vehicle is going to pop out nice and easy with a gentle pull or get hung up on that hidden tree trunk in the mud no one has noticed. Is your mate pulling you out slightly sideways from you and not dead straight on. This is exactly why i say recoveries are rigging as you should be derating gear due to the variables faced as well as having some understanding of angle factors, safe use of gear and the understanding of what may go wrong and how.75286

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[MB]

Awesome information, Cheers All Blokes!!
I’m assuming “side loading” is why we should only ever use rated ‘bow’ shackles for recovery. Is it still ok to use rated ‘D’ shackles for trailer safety chains? Some trailer configurations we’ve got can’t seem to fit bows only longer shanked D’s I guess their called?


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[GQtdauto]

Awesome information, Cheers All Blokes!!
I’m assuming “side loading” is why we should only ever use rated ‘bow’ shackles for recovery. Is it still ok to use rated ‘D’ shackles for trailer safety chains? Some trailer configurations we’ve got can’t seem to fit bows only longer shanked D’s I guess their called?


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I'm old enough to remember the pig tails that were welded to the tow bar , you just put the chain over that .

[Mike02Ti]

Awesome information, Cheers All Blokes!!
I’m assuming “side loading” is why we should only ever use rated ‘bow’ shackles for recovery. Is it still ok to use rated ‘D’ shackles for trailer safety chains? Some trailer configurations we’ve got can’t seem to fit bows only longer shanked D’s I guess their called?


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Bow shackles by design are made not only to fit wider straps / gear on them but to allow them to take a side load.
A D shackle should only be used straight on and are not designed for a side load.

Rated D shackles on a trailer are fine as as per what ET posted the link to above as long as its rated.
They say this:
"A Bow shackle will provide flexibility for greater angular movement compared to a “D” shackle."
So merely a recommendation that bow shackles should be used where possible.

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[MB]

Cheers Mike, ET’s kind link seems to error off my phone. http://www.nissanpatrol.com.au/forums/images/imported/2018/05/74.jpg


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[Mike02Ti]

Heres a screen shot of it relating to the shackles and chain
http://www.nissanpatrol.com.au/forums/images/imported/2018/05/75.jpg

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[the evil twin]

For those occasions when 8,000 Kg straps just aren't enough...

75291

[BillsGU]

It's complicated. Yes, there are formulas for recovery. They take into account weight being recovered, rolling resistance, terrain type, terrain angle, and a couple of other variables. The result is the pulling force required to get the crock out of where it is stuck. Army recovery mechs have used these formulas for many years. These calculations allow them to plan their recovery wrt equipment required, pull ratio, etc.

As far as equipment rating is concerned, ET is correct IMHO. All rated recovery equipment is rated for lifting and includes large safety margins. It has been determined by the recovery industry (again mainly driven by the Army at the time) that these large safety margins are unworkable and unnecessary. Again ET is correct in stating that using lifting rating for recoveries (here we are talking trucks, tanks and vehicles with serious weights) it would be impossible for even two people to lift the equipment. (Even then, the Army's recovery tank has a "small" winch installed to allow the main winch cable, connected to the "BIG" winch, to be pulled into place).

For this reason it was determined that recovery equipment would be rated by using 50% of the oringinal breaking strain. (An example would be a shackle with a one ton SWL and a safety factor of five would have a BS of 5 Ton. The recovery industry would use this 1 Ton shackle for a 2.5 Ton recovery).

It has been many years since I have done this type of training and things may have changed, however, if you correctly use rated equipment, the chance of it failing would be close to zero. Also, as I have stated in previous posts, you should always use a snatch strap no higher than 8000 kg for normal vehicle recovery. This ensures that the snatch strap is the "fuse" in the system and if all else fails, it will break before bits are torn off a vehicle.

[Bidja]

Have been reading thru and I would imagine that a BS or SWL would be the component that is rated at this certified working load condition. I would assume there would be a design safety factor built in on top of these limits, eg: static general design say 2.5:1 or for dynamic 5-10:1 depending on the operating environments and the potential risk and impact of failure.

[the evil twin]

Have been reading thru and I would imagine that a BS or SWL would be the component that is rated at this certified working load condition. I would assume there would be a design safety factor built in on top of these limits, eg: static general design say 2.5:1 or for dynamic 5-10:1 depending on the operating environments and the potential risk and impact of failure.

Pretty much...

A goodly amount of equipment which we use/borrow/pinch for recovery operations is manufactured to a Standard (A.S. in most cases) EG Rated Shackles.
Ergo Shackles are rated for lifting, tow bars are rated for towing etc.
None of these components are required by their A.S. to be rated/tested/manuf for recovery, there is no point as that is not the manuf intended use.

Soooo, some Standards work brilliantly for recovery use IE Shackle A.S. and some are absolute shit IE the Tow Ball A.S.
The Standard may or may not apply safety factors and again purely as an example in Shackles it will be 4 to 8 times depending on the class and grade.

Some specialist component manufacturers will proof test or rate against material strength alone.
An example of that is Recovery Points.
Some will send a prototype or example to a lab for destruction or proof testing, some will rate against material IE 'x' thick steel of 'y' grade with a min 'z' mm for any perforation from any edge is = to "A" tons.
These manuf are to be applauded and most will apply a safety factor of their choosing of 2 or more EVEN THO no A.S. applies

Finally, equipment like Snatchies have no Manuf Standards at all.
They only have an A.S Packaging Standard which covers what must appear in/on the packaging and/or labelling.
They are usually rated on material only and almost invariably have no safety factor applied so will fail at or about 'rating'.

All of which is why an 8 ton 'rated' snatchie will fling a 3.5 ton 'rated' Tow ball straight thru a human but tear itself to shreds trying to bust a 3.5 ton 'rated' shackle or snap before it rips out a 5 ton 'rated' recovery point.

[Dr Gary]

Hi mate you can only fit one 12mm flat plate to the drivers side to
fit one to the left you'd need to drop the bullbar. Look at my vender
thread and see if my "tee" shaped ones will fit on the outside of your bull bar
Let me know which style would suit would not take long to get some cut and coated.
Thanks mudski

Hi TD
I have your recovery plates on my 2006 3.0di. This model had capture nut attachment points on BOTH chassis rails, so I just needed to remove the "tow hook" and then bolt the plates INSIDE the chassis to existing capture nuts.

[Bidja]

Pretty much...

A goodly amount of equipment which we use/borrow/pinch for recovery operations is manufactured to a Standard (A.S. in most cases) EG Rated Shackles.
Ergo Shackles are rated for lifting, tow bars are rated for towing etc.
None of these components are required by their A.S. to be rated/tested/manuf for recovery, there is no point as that is not the manuf intended use.

Soooo, some Standards work brilliantly for recovery use IE Shackle A.S. and some are absolute shit IE the Tow Ball A.S.
The Standard may or may not apply safety factors and again purely as an example in Shackles it will be 4 to 8 times depending on the class and grade.

Some specialist component manufacturers will proof test or rate against material strength alone.
An example of that is Recovery Points.
Some will send a prototype or example to a lab for destruction or proof testing, some will rate against material IE 'x' thick steel of 'y' grade with a min 'z' mm for any perforation from any edge is = to "A" tons.
These manuf are to be applauded and most will apply a safety factor of their choosing of 2 or more EVEN THO no A.S. applies

Finally, equipment like Snatchies have no Manuf Standards at all.
They only have an A.S Packaging Standard which covers what must appear in/on the packaging and/or labelling.
They are usually rated on material only and almost invariably have no safety factor applied so will fail at or about 'rating'.

All of which is why an 8 ton 'rated' snatchie will fling a 3.5 ton 'rated' Tow ball straight thru a human but tear itself to shreds trying to bust a 3.5 ton 'rated' shackle or snap before it rips out a 5 ton 'rated' recovery point.

Yeh, recovery is very unpredictable. Component and equipment selection for use is primarily based on experience and lessons learnt or from listening to those we regard to have the appropriate knowledge or skill set. I certainly would not want to be in the near vicinity of a snatch or fastener failing resulting from recovery activity. Go Go slowly.

Those design safety factor I quoted were from non-tertiary level studies I undertook many yrs back (mech design cert) and worked many yrs on the civvies side of the fence involved in design, trials, test/evaluation and manufacture of gear (maybe similarly to yourself).

[MB]

Best technical conversation ever, good caring blokes!
Seen some Wild Bush shit in heydays hindsight:-(



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[PeeBee]

One important issue I believe is to calm down and think about what and how you are doing things. I have been guilty of rigging a recovery line then getting part way into the action to discover that adrenaline has clouded my decision making or the desire to get going and reach camp. Sitting back for a few minutes and calming down before commencing the task will certainly assist is a safer job execution and could very well result in lower strain on all components. Don't rush the task, its important to get it right the first time as opposed to having a more difficult recovery due to a careless approach.

[threedogs]

Dr Gary your right later models say 03 onwards had captive nuts under the chassis the
earli Diesels had 3 captive nuts on the inside of the chassis rails nut underneath like the later ones.
Early ones needed a special plate for inside the chassis rail to fit the second one , bull bar would need to come off as well .

[BillsGU]

Hmm. TD. Mine is a 2000 GU and as I said, Iron Man sell a kit that does not require removal of the Bull bar.

[mudski]

Hmm. TD. Mine is a 2000 GU and as I said, Iron Man sell a kit that does not require removal of the Buller.

Have you got a link to the kit? Or a pic. Yours will be the same as mine... Well, should be.
http://www.nissanpatrol.com.au/forums/showthread.php?14223-Fitting-GU-Recovery-plates

[threedogs]

maybe there is an inspection hole further
down the chassis either way it will just be a copy

[BillsGU]

The kit is not on Iron Man's site - I was speaking to the owner about the issue I have and he said "Hang on, we have a kit that will do the job". As I posted before, there are access holes to the rear of where the plate bolts to the chassis and the kit comes with nuts complete with rods welded to them that feed into the holes and allow the bolts to be fastened.

A copy of what? It's just a plate with a hole in it to allow a shackle to be attached.

[Big Gags]

I have some notes from way back and thought that some of the calculation factors used might be of interest/use to some of you guys....

Rolling Resistance (RR) = Vehicle Weight / Ground Factor.

Ground Factors:

Smooth hard road = 25
Long Grass that fouls the front and underside of vehicle = 7
Hard wet sand, gravel, Soft wet sand = 6 or 5 (it states that experience to judge the degree of sinkage is required)
Loose dry sand, Shingle Beach, Gibber Desert = 4 or 3
Soft clay and black mud = 2 (a mud-like plasticine would start at 2 and decrease with sinkage to 1 where wheels and axles are completely submerged)

Example: for a 2 tonne vehicle being recovered from sand RR = 2/4 = 1/2 = 0.5 tonne

Next factor is Gradient Resistance (GR) = (Vehicle Weight / 60) x Angle of Slope (degrees)

Example: for a 2 tonne vehicle being recovered up a 20 degree slope GR = 2/60 x 20 = 2/3 = 0.66 tonne

Final factor is Damage Resistance (DR). For a wheeled vehicle under 5 tonne you add 0.25 per tonne for each locked wheel.

The final calculation of Pull Required (PR) is PR = RR + GR + DR

For the example of a 2 tonne vehicle bogged in sand on a 20 degree slope and with no damage to wheels the pull required would be:

PR = RR + GR + DR = 0.5 + 0.66 + 0 = 1.16 tonnes.

There is then a Safety Factor (SF) applied to compensate for any errors and to make allowance for any unforseen resistance. The SF applied is a quarter of the PR figured.

So for the example, the Total Pull Required (TPR) is 1.16 x 1.25 = 1.45 tonne.

I cannot confirm how the different calculation figures were developed but I can confirm that the army recovery mechanics who are the guys who recover vehicles for a living use these calculations when planning their recovery activities. Recce Mechs as they are known will also utilise snatch blocks to achieve the required levels of pull with Simple, Compound, Direct, and Indirect tackle layouts. The simplest layout for self-recovery that provides a mechanical advantage is to attach a snatch block to your anchor point and then loop your winch rope around the snatch block and attach it back to the vehicle. This effectively doubles the capacity of your winch (less some friction losses) and so if you have a 9,500 lb winch you are now pulling at 19,000 lb which is about 8.5 tonne and should be enough to get you out of pretty much anything!!!

[MudRunnerTD]

If I may stick my nose in here ,whatever you use for the rating or SWL etc as you both have pointed out and done a great job of explaining but to the layman am I right or wrong in assuming there is no way of knowing what weight your playing with if the vehicle is bogged to the floor ?
Seems to me that in my example it would be almost impossible to determine the weight and therefore the Breaking strain required , which maybe why so many recoverys end in tragedy or near miss .
For me if I can't winch I dig and I'm an expert plus at getting bogged .


I have some scenarios in this thread that you can use to get your head around how bad your recovery might be based on the depth of the crap your stuck in. Well worth a look

http://www.nissanpatrol.com.au/forums/showthread.php?1984-Recovery-The-Fundamentals

[BillsGU]

Yep Big Gags - they are the formulas I remember using years ago.

[threedogs]

Personally Id prefer a plate with nuts welded on , rather than just washers and nuts
Ive seen some pretty shoddy GQ and GU chassis over the years, hate to pull one
out of the chassis.
Just something to think about

[MB]

Pretty sure TD that’s what we welded up for AB’s GQ ARB bullbar years back mate. 5ish,mm plate with nuts tacked on three sides and galvanised - aligned with OEM chassis holes?


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[BillsGU]

Personally Id prefer a plate with nuts welded on , rather than just washers and nuts
Ive seen some pretty shoddy GQ and GU chassis over the years, hate to pull one
out of the chassis.
Just something to think about

A plate won't fit into the inspection hole. The only way to use a plate (on an early GU) would be to increase the size of the inspection hole or cut/bend the front of the chassis rail, either of which I would prefer not to do.

The majority of the forces on the recovery point would be shear and mostly taken up by the sides of the bolts. Correct bolt type is critical. If your chassis is that shoddy that the bolts may pull out I would think you have serious problems to worry about.

[PhillipA]

Great reading all of your thoughts on this. It is important and as said recovery potentially can be dangerous


Hey Mudrunner, That old link you put on is a good one and very comprehensive. Like PEE BEE said we need to have a little think about situations when we get into them and what possible things will happen when we finally go about the recovery. Just like

painting its all about the preparation and the last thing is the paint. I've been in some pretty bogged down situations and remember the first time thinking it was all about the engine just working harder to pull me out. Now days its all about the digging first and jamming some traction under the wheels, clearing underneath before the last easy bit of the snatch strap.

Apart from that I was able to attach my 2 front recoveries the same left and right ..... chassis already had the holes and nuts in them enabling me to bolt new h/tensiles straight in without the worry of trying to slide new nuts in on those wire things.
Winch has been fitted and tree protector as well as winch extension, damper etc so ready for it. We only are on flat ground but there are some bad patches of sand and all this is mainly to attack it feeling more secure in the knowledge if we get bogged it not the end.
We will be going through with tyres let down to 15-20 psi and hopefully do the sand when it is cool so much easier and firmer.