The 4 High Tensile (12.9) 10mm bolts used to hold the front bumper/winch-tray to the chassis have a shear strength of 1.5 tons in 6mm plate section (actually they rip the steel plate @ 1.05T).
There are 4 bolts holding the winch plate/front bumper onto the chassis, the chassis (being a ‘box section’) will therefore distort/tear @ 8.4T (8 points @ 1.05T)
You really want the 'strap/sling' to snap before that happens...

I would love to see your working out of that please.

Cheers
 
I would love to see your working out of that please.
Cheers

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 ?
 
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 ?

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
 
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
He obviously hasn't had the real life experiences we have! Do you remember Brickhill and that deep hole we pulled you out of ;)
 
Thats one of the reasons why I now use soft shackles. :p

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



 
Hi @gstuart

I am good thanks, how are you doing?, Yeah I have seen that video on the soft shackles. I did make a few for fun from an offcut I had, but not something I would use in anger.

These are an interesting watch, Especially the bridle one.





Cheers
 
Hi @gstuart

I am good thanks, how are you doing?, Yeah I have seen that video on the soft shackles. I did make a few for fun from an offcut I had, but not something I would use in anger.

These are an interesting watch, Especially the bridle one.





Cheers


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
 
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

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 :D

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 ?
 
@ 9000Kgs (9.92ton)

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
 
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 :D

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
 
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.
Cheers

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
 
However, given that you can't calculate Kg to Ton it may be wasted .... 9000 Kilogram = 19841.6 pounds = 9.920802 ton = 9 tonne

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
 
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.

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 :)



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

You could be right :eek:
 
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

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.
 
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.

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
 
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 :eek:
 

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