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Posted By bazthesesh
Hi i wonder if anyone can tell me what sort of pressure would need to be applied on a double coupler to make it spin a ledger
i know its slip resistance is 6.25 kn but is this the same when applied to a puncheon that is only fixed once at its base and is having pressure applied to it to push it out?
cheers
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Posted By Merv Newman
I'm sorry, but is this a Friday windup ?
If not then I must declare my total incompetence and refuse to offer an opinion. I didn't understand a word !
Merv
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Posted By John Webster
Merv,
I know that a puncheon is just over 318 liters (sure you did too), but the rest must depend on knowing a double coupler from ones putlog coupler :-)
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Posted By Robert S Woods
Come on now Merv it's a basic scaffolding erection question.
I cannot see how this can happen as the ledger would be captured at both ends, and the puncheon it is attached to is properly braced. The puncheon shouldn't be having pressure exerted on a horizontal plane as it is designed to be under compression and it should be crossed braced if it is on the bottom tier.
If you need any further help get in touch.
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Posted By Robert S Woods
There should be an if in the first sentence of my reply. I'll let you decide where.
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Posted By bazthesesh
sorry if the first post was a bit garbled typing is not my forte
the reason behind my post is this.
a person leaning on a puncheon that was only fixed once to the bottom ledger moved..i say moved swung would be better,the double in question was not tightened sufficiently to hold it all but i was wondering even if the double was fully tightened what sort of force would be needed to make it turn on the ledger
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Posted By Des Daly
Having worked in Scaffolding for the last 30 years I understood immediately what you were talking about. Although you may find single puncheons on a site, the correct fixing is to two ledgers. As to whether it would spin the ledger - in practice, and from my own experience, it is the double that rotates rather than the ledger ( being held by more than one double coupler). Have a look in BS 5973 if you still have a copy or try the new standard BS EN 12811. There have been many serious accidents due to the issue you are raising...so, good question!
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Posted By Merv Newman
Look. are we talking Tall Ships here ? With standing and running rigging, halyards, painters and cables and so on ? "Another reef on the t'gallnt mnsl mr christian afor she blows the sticks out of us ! Start that man !"
I'm lost.
Incompetent. Get back to yer kitchen.
Interestingly, this thread does demonstrate the diversity of our profession. The left hand of which DOES NOT HAVE ANY IDEA of what the right hand is talking about.
Innit fun ?
At what point do you decide that you are NOT competent and have need of more expert advice ? (don't look at me)
Discuss
Merv
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Posted By bazthesesh
cheers Des
and i did mean the double spinning and not the ledger itself
i have tried searching scaffold manufacturers sites but can find no information on this.i am assuming this would be classed as some sort of torque
Merv keep taking the pills they will help honest they will
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Posted By Martyn Hendrie
I'm lost too.
Are we talking about a single "right angle coupler" being used to hold a return guard rail and what torque should it be tightened to to prevent the return guard rail rotatng?
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Posted By bazthesesh
basically it was a 2.4m upright scaffold tube fixed to the ledger with one right angle coupler
so while standing on the lift above the point where it is fixed how much pressure would need to be applied to make the double move around the ledger based on the idea that the double coupler is tightened correctly
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Posted By bazthesesh
the chap in question here (a scaffolder of almost 40 yrs experience) fell 7 ft from this scaffold and broke both wrists after several operations he will never scaffold again.By the way this wasn't a scaffold he had erected...
so can anyone find out how much pressue/torque it needs to make a double spin on its ledger?
cheers
baz
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Posted By Pete Wright
Could you not safely replicate the scene and with the aid of a torque wrench and suitable sized socket carry out tests? I think the mathmatics may stump most of us.
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Posted By 9-Ship
Not being a scaffolder, I'll still throw my bit from a mechanical engineering point of view.
Trying to replicate the exact conditions of the accident will probabably be difficult - even using the bits of scaffold from the accident.
I would have thought if you are trying to calculate the torque required that is quite easy in theory Torque = Force x Radius
However, the actual force required will vary due to the inherent friction in the system/contact surfaces. e.g. corroded bits of scaffold tube/surface will obviously have greater turning resistance than new (or lubricated surfaces - I'm not suggesting they were lubricated, I am just making a point).
Then there is the friction between the fixing and the masonry/cement that is is secured into - I would have thought that this could potentially vary the greatest.
Just my thoughts
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