recovery point ripped clean from chassis
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NA_R33
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Sorry to see that mate, its a real concern.
I believe the thread started was using rated recovery points bolted to the factory locations.
My question is surely he cant have been the first person to have a d40 snatched from the front. What are others doing for front recovery points?
I might have to do some investigating and see if i can fab something up that I think will hold up. The front of the chassis rails on the king cab are a pain in the rear as the hole in the front of them isnt big enough to put a substantial enough doubler plate inside the chassis rails... might just have to make the holes a little bigger, That way i can tack some nuts on the drivers side too where there are no factory captive nuts on the king cab.
I believe the thread started was using rated recovery points bolted to the factory locations.
My question is surely he cant have been the first person to have a d40 snatched from the front. What are others doing for front recovery points?
I might have to do some investigating and see if i can fab something up that I think will hold up. The front of the chassis rails on the king cab are a pain in the rear as the hole in the front of them isnt big enough to put a substantial enough doubler plate inside the chassis rails... might just have to make the holes a little bigger, That way i can tack some nuts on the drivers side too where there are no factory captive nuts on the king cab.
I've used the front recovery point to reverse recover 2 vehicles so far now ...
firstly an older patrol stuck on the side of a snowy track
secondly, a D22 that was stragically bogged, just north of healesville (can anyone guess who that was?)
Due to this post i've quickky gone out and checked the recovery point - it still seems very intack to me.
firstly an older patrol stuck on the side of a snowy track
secondly, a D22 that was stragically bogged, just north of healesville (can anyone guess who that was?)
Due to this post i've quickky gone out and checked the recovery point - it still seems very intack to me.
heata
Member
Not sure what an engineer would say, but I can't see how the stress would be any different on each end of the strap. As I see it, the stress is cause by tightening of the strap, I imagine that what ever the force applied at one end (rescue car driving) must be created by having an equal force put on the other end of the strap (stuck car) and when the the stuck car is released, the force is reduced. But thats just my thoughts
The force is equal and opposite. The elasticity of the strap creates an impulse. Initially the recovery vehicle exerts a force on the strap, over a certain period of time. This energy is then released over a shorter period of time, and with any luck, the resultant impulse is greater than the force required to move the stranded vehicle. During that impulse, the same force is applied to both eyelets of the strap as the strap tries to return to its original length. So, the same force is exerted on each eye. That doesn't however take into account any off-centre recoveries, which will change the loading scenario for one or both recovery points.
What Dion said. The only way to make it different is if one vehicle is using an equalising strap, then half the load is placed on each of the two recovery points.
Off-centre pulls increase the risk of damage - force vectors are not straight down the chassis. Steel is excellent in tension, good in compression but it's malleable - meaning it will bend easily, stretch less easily - a straight pull will stretch, a off-centre pull will bend, and that's your chassis too. Equalising straps can be used to reduce the risk.
(The whole reason why they use steel inside concrete for construction is BECAUSE steel is so good in tension - it holds the concrete together. Concrete is excellent in compression, but hopeless in tension - it will crack readily if you pull it apart. Put the two together and you've got a structural member that is greater than the sum of its parts. Hence our bridge spans are pre-stressed - stretched steel with concrete poured over it and allowed to set - or post-stressed - conduits over which concrete is poured, allowed to set and then steel cables are tensioned up once the concrete is dry).
Off-centre pulls increase the risk of damage - force vectors are not straight down the chassis. Steel is excellent in tension, good in compression but it's malleable - meaning it will bend easily, stretch less easily - a straight pull will stretch, a off-centre pull will bend, and that's your chassis too. Equalising straps can be used to reduce the risk.
(The whole reason why they use steel inside concrete for construction is BECAUSE steel is so good in tension - it holds the concrete together. Concrete is excellent in compression, but hopeless in tension - it will crack readily if you pull it apart. Put the two together and you've got a structural member that is greater than the sum of its parts. Hence our bridge spans are pre-stressed - stretched steel with concrete poured over it and allowed to set - or post-stressed - conduits over which concrete is poured, allowed to set and then steel cables are tensioned up once the concrete is dry).
Red Dog
Member
dec0guy
Member
Not totally true, also need to consider acceleration and jerk (or change in acceleration) as the bogged vehicle being pulled will have a much larger 'jerk' compared to the car pulling. Excessive jerk is also what causes whiplash in accidents.
Third derivative of position
Third derivative of position
I don't agree with that, I'd argue the jerk for the recovering vehicle in an unsuccessful recovery is much much higher (and the ~-20ms^-2 acceleration would cause the most occupant discomfort), and regardless of the vehicle's speed and all subsequent differentiations (acceleration, jerk, jounce), the load on the recovery hooks will be equal. Even if the strain rate was higher for either vehicle, yield and tensile strength increase with strain rate, so you could disregard strain rate and analyse a static peak loading.
In any case, the laws of physics dictate that every action has an equal and opposite reaction. What happens on one end of the cable happens on the other too.
NA_R33
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Sorry didnt mean to spark a physics debate, what has been said is correct, to every action there is an equal and opposite reaction, one of newtons laws that cannot be argued.
I simply meant that in reverse you probably wouldnt achieve the same sort of speed as you would going forwards.
I simply meant that in reverse you probably wouldnt achieve the same sort of speed as you would going forwards.
K
krunchi
Guest
We are going off topic guys.
Looks like the point of failure is the chassis or captive nuts.
You can put what ever rated point you want but if useing the stock nuts in the chassis it makes no difference.
Any diy solutions to getting a better mount point? Would be nice ot put a plate in teh chassis but how would you get in there with out bullbar removal?
Looks like the point of failure is the chassis or captive nuts.
You can put what ever rated point you want but if useing the stock nuts in the chassis it makes no difference.
Any diy solutions to getting a better mount point? Would be nice ot put a plate in teh chassis but how would you get in there with out bullbar removal?
You could get longer high tensile bolts (if necessary) and put the recovery point on the bullbar mounting point.
A winch-capable bullbar is supposed to be mounted on the chassis in such a way that should a winch be used, it will transfer that load to the chassis correctly. Mounting a recovery point off those mounting points ought to provide the same security.
A winch-capable bullbar is supposed to be mounted on the chassis in such a way that should a winch be used, it will transfer that load to the chassis correctly. Mounting a recovery point off those mounting points ought to provide the same security.
K
krunchi
Guest
Well until i work out how to mount to my ARB bull bar mounts i will caustiosly do slow stach recovery if required.
Scubamurph
Member
New to this game. Where would I be able to get recovery hooks/eyes for my 08 ST-X?
Do I need to fit to front and rear or is there something else for the rear?
Murph
Do I need to fit to front and rear or is there something else for the rear?
Murph
ARB and TJM would both sell them. At least one on the front and one on the rear is good.
If you have a 3T rated towbar on the rear, it will be mounted on both chassis rails so it makes a good recovery point - get yourself a hitch receiver shackle (about $50 at ARB).
Anything that you do add to the vehicle should be mounted with the proper high tensile bolts (8.8). If they're not, they could break, which could cause the recovery hook to become a projectile.
If you take your vehicle to a 4WD store, many of them are experienced 4WDers and can give you good advice about what you need while you're looking at the vehicle.
If you have a 3T rated towbar on the rear, it will be mounted on both chassis rails so it makes a good recovery point - get yourself a hitch receiver shackle (about $50 at ARB).
Anything that you do add to the vehicle should be mounted with the proper high tensile bolts (8.8). If they're not, they could break, which could cause the recovery hook to become a projectile.
If you take your vehicle to a 4WD store, many of them are experienced 4WDers and can give you good advice about what you need while you're looking at the vehicle.
Scubamurph
Member
Cheers Tony.
Will search out my local 4x4 place and have a chat with them.
Towbar is a factory fitted 3T jobbie. Will look for the hitch shackle.
Murph
Will search out my local 4x4 place and have a chat with them.
Towbar is a factory fitted 3T jobbie. Will look for the hitch shackle.
Murph
I can't find one on ARB's online catalog although ARB is the place I bought mine from, but here's a picture of one at Supercheap so you know exactly what you're looking for.
Wait, I can use the picture on their site and bring it in here, it'll work as long as they don't drop the product or move stuff around on the website:
Wait, I can use the picture on their site and bring it in here, it'll work as long as they don't drop the product or move stuff around on the website:
