neilly
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Straps and Shackles
- Thread starter OttoGSP
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Do you think i'm wrong ?
These guys are suggesting 0.5T per bolt. I think that is a tad low as we are in a box section and the 'steel plate' is therefore 4 x 3mm sheets (2 top and 2 bottom) at circa 550MPa
https://forums.lr4x4.com/topic/70772-strength-of-m10-bolt/
This paper discusses the relative shear strength as well as the yield. I think the yield of the dogs and the winchmount is the weakpoint, obviously if mild steel bolts (or worse still, stainless) are used then the shear becomes the weakpoint.
The use of a 3mm and an 8mm plate represent a reasonable facimilie of a winch bolted on a dumbiron and the IOP results are 14.01 (1.5ton - ish). This would equate to 12 tonne however as the 2 bolts are quite close together i'd be inclined to take around 25% off that figure and go with circa 9 tonne.
https://iopscience.iop.org/article/10.1088/1757-899X/713/1/012031/pdf
What do you think @neilly ?
neilly
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OK, so you did not work it out then , you made assumtion on their data.
I was expecting hard calculations,Especially when you are stating they rip the 6mm steel at 1.05T. Never mind.
Cheers
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He obviously hasn't had the real life experiences we have! Do you remember Brickhill and that deep hole we pulled you out of
Hicap phill
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no time to work out shear calculations. I just use bigger shackles. These are also easier to find/handle when they fall in the mud
neilly
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Hicap phill
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Are they stronger than bailing twine?Thats one of the reasons why I now use soft shackles.
Cheers
neilly
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Thats one of the reasons why I now use soft shackles.
Cheers
hi mate @neilly
funny enough watched this the other day ref soft shackles , plus did u ever see the test ref ratchet straps
hope there of interest buddy , plus as a side note that I must admit never used a Kinetic strop , I bought my recovery strops from Damar
ps, hope this finds u well
neilly
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hiya @neilly
good to hear ur ok mate , me, still waiting for an appointment at Stanmore for back surgery consultation
did wonder that buddy if you had seen the shackle one before
many thanks, I’ll check them out , must admit do like that bridle idea, plus think we’ve all seen where some on a recovery just gun it without thinking of the dangers or consequences
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Not sure what you are getting at here ?
Yes I use data tables ... who is the "their data" you are refering too ?
If it is 'Dave W' on the LR4X4 forum i'd be interested in seeing that discussion
Are you perhaps questioning that the defenders chassis steel has a yield strength of more than 550MPa ?
Do you think its made from a high carbon structural steel perhaps type S500J0 ?
So what force do you think is required to deform/pull off the front bumper/winch tray from a defenders chassis ?
I (based on my knowledge) put this @ 9000Kgs (9.92ton), so i (personally) wouldn't pull more than 5000kgs which is well above straight pulling a landy out of a hole but I tend to use a pulley and an anchor point to share the load.
What force do you think will pull off a tow hitch from a landy ?
neilly
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You seem to think I am having a dig, I only asked if you had the working that you used to calculate this information. where you stated the bolt would tear through at 1.05T and the shear of a 12.9 10mm bolt is 1.5T.
However, not sure on that as you have written 9000LKGs is 9.92T.
I do not see any of your calculations so will not bother asking any further questions.
Cheers
Hicap phill
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Not sure what you are getting at here ?
Yes I use data tables ... who is the "their data" you are refering too ?
If it is 'Dave W' on the LR4X4 forum i'd be interested in seeing that discussion
Are you perhaps questioning that the defenders chassis steel has a yield strength of more than 550MPa ?
Do you think its made from a high carbon structural steel perhaps type S500J0 ?
So what force do you think is required to deform/pull off the front bumper/winch tray from a defenders chassis ?
I (based on my knowledge) put this @ 9000Kgs (9.92ton), so i (personally) wouldn't pull more than 5000kgs which is well above straight pulling a landy out of a hole but I tend to use a pulley and an anchor point to share the load.
What force do you think will pull off a tow hitch from a landy ?
I go by experaince
Hanging down a bank with a rear winch and with a rally car hanging of the front winch.
Unsure of the total weight but I trusted the extra bolts in the front winch bumper.
I’m sure it’s more easier to pull the 4 bolts out the winch than pull the bumper off.
I’m sure there a 4 bolts vertical 1 & 2 horizontal
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Here you go,...
Your are right, I don't do the math any more, I look it up in a table (here's one https://eurocodeapplied.com/design/en1993/bolt-design-properties)
However, given that you can't calculate Kg to Ton it may be wasted .... 9000 Kilogram = 19841.6 pounds = 9.920802 ton = 9 tonne
Cheers
neilly
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Hmmmm, maybe you need to think about the locality of your tons................in the US are you? Oh no it says Scotland..... using some dodgy conversion site then.
I give up.
Cheers
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If your landrover was suspended vertically by the rear winch with a rally car on the front winch, swinging gently in the breeze.
The total weight on the anchor would be the weight of the landy (2500kg) + the rally car (1350kg) = 3850kg (give or take).
You are fine. You could attach another rally car and still be safe as even with 2 cars on the front the total wieght on the anchor (which as it is directly connected to your rear winch is effectively the same) is 5200kg.
Because you and the car are on the ground, on a slope, then a portion of your weight is supported by the ground. The total wieght on the anchor (and the landy) is therefore less.
The math (mainly for @neilly ) is: wieght = (wieght of car in kg) x 9.81 (gravity in ms2) x sinAngle(of slope)
To be more safe i'd tie the front winch to the anchor and reverse down to the rally car and attach that to the back of your landy using a bridal off your chassis.
That way you could bring up 3 or 4 rally cars
You could be right
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It's not 'dodgy' you muppet.
None of this French ****e when I leaned engineering, 39.3701 thou = 1 millimeter, 2.20462 pounds = 1 kilogram. An inch is an inch and a ton is a ton. Not only is it spelt correctly (tonne WTF ?) but it's a stable measurement thats been used for hundreds and hundreds of years. The industrial revolution was built on it.
A ton is not based on a lump of platinum and iridium locked in some French farts cellar. For years the French defined a measurement of length as the pied du Roi, or a “king’s foot.”
Recently a Brit (Brian Kibble) invented a set of scales using Planck's Constant that has made this lump of alloy superfluous.
Mon Dieu, was the cry.
Perhaps you are youth @neilly ?
Do you remember £.S.D ?
When there was 240 pennies in a pound. 20 shillings ?
You had to be good at maths years ago, now it's (obviously) dumbed down and not understanding how things work and counting to 10 is the new achievement.
neilly
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you used US tons you pillock. In your conversion if you cannot see that the trusting you understand lifting is a joke!
get a grip
cheers
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I'm not clever enough for all this. I have no clue how much force of going to be involved when i stamp on the accelerator so I'm more gentle when using a skinny rope versus a big fat one
