D
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There's a big recovery hook at the front,don't think there is one at the back,i could be wrong.
Will have a look in the light 2morrow!! :lol:
Will have a look in the light 2morrow!! :lol:
You tube link re: kinetic recovery straps
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Terranosaurus
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cosmic said:
Depends what sort of tow bar you've got, if its the type with a drop plate ether side it gets in the way of the recovery eyes at the back.
D
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Don't see no recovery eyes HB,are they where the tow bar attaches to??
If so,yes they are not usable!!
If so,yes they are not usable!!
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thor said:
your biggest concern is a bit falling off the landy and catapulting towards you at the sped of sound :lol:
I think all Nissan Terrano towbars use the 2 rear recovery eyes as mounting points. But as the towbar itself is secured with several 8.8 hi-tensile bolts, there isn't likely to be much chance of the bar itself or its mounting failing.
The issue with towballs is more how they get used for recovery, they are not a "secure" point for ARC competition, they are only classed as secure if they are mounted on a horizontal flat surface - think Land Rover front bumper top, with the ball then facing rearwards rather than upwards - vertical mounting bolts rather than horizontal. And while ARC do allow the use of towballs, the small print of "minimum standard is a towball" needs to be considered. Jate rings are not that highly thought of, the military are more likely to use them for tie down loops rather than recovery points. But then they all have big NATO hooks anyway, and usually a tow pintle type front bumper!
Towballs should also not be used with shackles secured around them, they are highly likely to fail if used in this way, even though some of the larger shackles fit quite snugly on the neck of the ball and would seem to be quite secure. The loading on the ball if used with a shackle can break the neck of the towball. There is also an issue with using a towball for KERR straps, again due to the excessive loading. Some of this is based upon the US & Australian type of toball, which is not the same as the UK equivalent, but all the same problems have been reported with UK spec towballs in recovery situations. Possibly one of the best options for those with a towbar would be to get a towing jaw in place of a towball for greenlaning, meaning a secure recovery point to the rear would be available. Not an option with a swan neck bar though, which is why I had this made up: http://i42.photobucket.com/albums/e319/JonathanMimnagh/_B170002.jpg
Ultimately the decision has to be based upon the state of the vehicle, how well stuck it is, and the recovery points available. Also KERR should probably be the last resort of recovery, having tried all other means available, including jacking & digging etc.
I've got a KERR strap, and have never used it yet. One major problem about using a KERR is that if it is secured to just one recovery point, the forces may twist the chassis rail, it is probably best to use a "bridle" to spread the load between two points. Unfortuanetly for terrano owners, they only have 1 front recovery hook, which would preclude the use of a KERR in most situations. I'd probably prefer to put the hard work in & use the Tirfor, and if that did not do the job, I'm not sure a KERR would either!
The issue with towballs is more how they get used for recovery, they are not a "secure" point for ARC competition, they are only classed as secure if they are mounted on a horizontal flat surface - think Land Rover front bumper top, with the ball then facing rearwards rather than upwards - vertical mounting bolts rather than horizontal. And while ARC do allow the use of towballs, the small print of "minimum standard is a towball" needs to be considered. Jate rings are not that highly thought of, the military are more likely to use them for tie down loops rather than recovery points. But then they all have big NATO hooks anyway, and usually a tow pintle type front bumper!
Towballs should also not be used with shackles secured around them, they are highly likely to fail if used in this way, even though some of the larger shackles fit quite snugly on the neck of the ball and would seem to be quite secure. The loading on the ball if used with a shackle can break the neck of the towball. There is also an issue with using a towball for KERR straps, again due to the excessive loading. Some of this is based upon the US & Australian type of toball, which is not the same as the UK equivalent, but all the same problems have been reported with UK spec towballs in recovery situations. Possibly one of the best options for those with a towbar would be to get a towing jaw in place of a towball for greenlaning, meaning a secure recovery point to the rear would be available. Not an option with a swan neck bar though, which is why I had this made up: http://i42.photobucket.com/albums/e319/JonathanMimnagh/_B170002.jpg
Ultimately the decision has to be based upon the state of the vehicle, how well stuck it is, and the recovery points available. Also KERR should probably be the last resort of recovery, having tried all other means available, including jacking & digging etc.
I've got a KERR strap, and have never used it yet. One major problem about using a KERR is that if it is secured to just one recovery point, the forces may twist the chassis rail, it is probably best to use a "bridle" to spread the load between two points. Unfortuanetly for terrano owners, they only have 1 front recovery hook, which would preclude the use of a KERR in most situations. I'd probably prefer to put the hard work in & use the Tirfor, and if that did not do the job, I'm not sure a KERR would either!
G
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JonathanM said:
Nice piece of kit that Jonathan, are you using high tensile or stainless bolts with it?
I'm currently looking at something similar for mine, as I have no towbar fitted just recovery points. I want a towbar for taking the van to events but need it detachable or demountable.
Two years ago I saw one like yours for the first time at a LR show and it had been imported from USA, now they are available commercially from Scorpion racing and Disco parts. You can buy a receiver that bolts into removeable tow bar and accepts a shackle.
http://www.discoparts.com/asp/d-no.asp?ProductID=322&Process=1&CatID=25&SubCatID=62
as you see not cheap, but quality (and life) never is.
thor said:
If you are only going to do fairly gentle greenlaning with your motor, then you have the option of leaving your towball exactly where it is. David Bowyer is an authority on offroading and I bet that several members have bought some of his products. You might find this article interesting http://www.difflock.com/offroad/bowyer/ropes1.shtml In places, it seems to contradict some of the guidance offered by some members in threads on this forum.
Cheers
Andrew
G
Guest
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andrewk said:
Thats all it is, guidance and opinions based on experiance of each member. Opinions will always vary and often be contradictory. Its down to the individual to make his/her own decision based on that. Using this forum (or any other) is part of the research that goes into that.
In any form of off road recovery, a diffinitive answer cannot be given untill you can asses the situation and each situation is differant.
David Bowyers advice and instructional techniques are second to none, they always make interesting reading and are worth the effort.
I'm not a technical person, but do understand a little about the forces and stresess caused by levering, pulling etc, so my opinion is:
The towball would be adequate for most of the situations you are likley to encounter during normal easy to moderate green laninng. If you are intending to do some rough or extreme work and are intending to spend money modifying other areas of your vehicle then a shackle/receiver would be a good investment.
G
Guest
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mav said:
Hi Mav
I think its the link andrewk may have meant as if you scroll right down there is a little about towing eyes, nato hitches, and Land Rover shackles.
mav said:
No, it's content has not changed. Whilst all of the article is interesting and relevant to the discussion in the thread, this bit seems especially relevant - "Without doubt the standard Land Rover supplied fixed height rear towing unit with either a towing ball or universal jaw and ball is the best for the majority of on and off road recoveries."
Members may well find the whole series of articles about offroad driving interesting if they haven't already read them, starting from here: http://www.difflock.com/offroad/drivingoffroad.shtml
Cheers
Andrew
cameraman said:
That seems very sensible to me.
I've been doing a little research this morning, to try and put this in a better context. Note that all the figures below relate to yield strength - i.e. the highest load that can be applied without permenanent deformation. Ultimate strength (i.e. breaking strength) is about a third higher.
1) The towball neck on my Patrol is 28mm minimum diameter. This is approx 0.95 sq.in area. I don't know exactly what kind of steel is used in the construction of a towball, so we'll make the probably conservative assumption that is has a yield strength of say 500 MPa (8.8 steel is 660 MPa). This is equivalent to 72.5 Kpsi (kilo pounds per square inch) or about 0.95*72500/2240 = 30 tons.
2) Standard flanged towballs are fixed to towbars using 2 x M16 8.8 steel bolts. These have a yield strength of 10.25 tons each - i.e. 20.5 tons total
3) The towbar on my Patrol is fixed directly to chassis rails using 6 x M12 8.8 steel bolts. These have a yield strength of 5.5 tons each - i.e. 33 tons total.
It would seem that the M16 bolts that hold the towball onto a towbar are more likely to fail than anything else - assuming, of course that the vehicle chassis hasn't rusted to the extent that it starts to look a bit like a rust coloured lace doyley (read that as meaning beware of 40 year old Series Landrovers). I've never heard of M16 bolts failing during an attempted recovery. I've only ever heard third-hand anecdotal stuff about towball failure - but no hard evidence. Has anyone got any real facts or case histories?
Cheers
Andrew
cameraman said:
8.8 hi ten bolts Andy, and it is based upon the concept of the detachable receiver system that is popular in the states. Got it made by a company who make bespoke towbars for vehicles that do not require type approval.
JonathanM said:
That is an article about failures during the use of snatch straps (kinetic ropes). In any case, there is no detail about precisely what failed or how it was attached to the vehicle in the first place.
Have a look at this one. See: http://www.tgatrading.com.au/PDF/UniversalShackle.pdf
It's an Austrailian invention that apparently makes vehicle recovery safer - using a "Univeral Shackle" attached to a rated towball. Some interesting test results at the end, which don't fully agree with some of my numbers above - but definitely don't support a position that locking a shackle over a towball is unsafe. As I've said previously, a standard 4.75 ton tested shackle will lock over a 50mm towball, pretty much what is being suggested in the article.
It is also interesting to note that a standard 50mm towball is more than twice as strong as the recovery hooks fitted to most 4x4s (the test doesn't say what failed at 12.8 tons, it may have been the towball fixing bolts rather than disintegration of the towball itself). On the front of the Trooper I had, the hook was rated at 4 tons but was affixed to a chassis rail by 2 x M10 8.8 steel bolts (as most are), which have a yield strength in tension of 3.8 tons each. In shear, the yield strength for the pair of bolts would be about 0.75 x 3.8 x 2 = 5.7 tons which agrees quite closely with the test results.
I think we need to be clear what we are talking about here. I'm thinking primarily of the relatively gentle recovery of stuck 4x4s on a typical greenlaning day, using a recovery strap or rope, not a snatch recovery using a kinetic rope. I cannot see any real reason why a towball cannot be used in these circumstances, providing due care is exercised during the recovery - and providing, of course, that both the recovered and the recovery vehicle are structurally sound.
Cheers
Andrew
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Interesting link andrew, it also echos my point in a previous thread that the strap is the safest thing to break! Better flying strap than flying towball!
I is my opinion that when a vehicle is stuck in the mud it is best to leave it where it is until the 'sun comes out and dries up all the rain!'
it worked for incy wincy spider :wink: :lol:
I is my opinion that when a vehicle is stuck in the mud it is best to leave it where it is until the 'sun comes out and dries up all the rain!'
it worked for incy wincy spider :wink: :lol:
J
jace
Guest
incy had built in winch with special rope stronger than steel lol!
