Lock nuts: the engineer's view

I borrowed an old NSU quickly from a workmate when my "real" bike was off the road. It was three speeds with a dual seat. My girlfriend wanted me to buy it.
 
PuffTheMagicDragon said:
Even better, stainless self-tappers are much less expensive than stainless woodscrews.
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I hadn't considered cost! The issue for me is most of my woodscrews are countersunk head, most of my self tappers are round head or pan head - for fixing something like a thin metal bracket to wood the self tappers are perfect.
 
Anthony said:
Can anyone please help explain this from the website

http://www.boltscience.com/pages/basics2.htm

Why is the loade on the bolt less when tightenedm after all load is still transferred to the support plate via the bolt regardless of whether the nut is up tight or wound almost undone. What am I missing?

Ants
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When you add the extra load the bolt will stretch (just a little) if the nut is loose then thats all that happens. If the nut is tight then the effect of the stretch will be to reduce compression between the bracket and the support plate. Thats where the reduction in extra bolt load comes from. So, while the overall load on the bolt is less if the nut is loose, the increase in load is less if the hut is tight.
 
Interesting reading indeed.
I have recently returned from commissioning work on one of the new West of Shetland installations and every bolt on the drill derrick is made up with the deep nut first followed by the shallow nut - the reverse of what the website states.
It is also the way I assemble them though why I can't recall - perhaps because of the fear of shearing the thread before full torque is achieved.
I would have thought that if every nut and bolt in one of the most hi-tec derricks in the world was assembled aot, then it might have been picked up by now?
 
I inspect derricks, the majority use Palnuts. Nobody uses double nuts or old style thin locknuts these days. Are you sure it's not some modern lock nut design? A Palnut looks like an old thin style lock nut and sits on top of the structural nut.
 
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To my untrained eye, these appear to be a normal nut and thinner lock nut. Whether they are Palnuts or not I couldn't say.
It is unlikely I will be back out on that installation but I will try and have a pic sent to me.

And having just googled Palnuts, I am familiar with this type and, no, this not what was used on this structure.
 
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afterpegassus said:
Yes.
I am unlikely to be back there in the near future but will try to have a pic sent to me.
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What's the name of the rig? I really doubt that it is a thin lock nut, but you never know these days. I had all the nuts changed out on the Lunskoye Platform derrick as they were the wrong grade.
 
BlowingOldBoots said:
I inspect derricks, the majority use Palnuts. Nobody uses double nuts or old style thin locknuts these days. Are you sure it's not some modern lock nut design? A Palnut looks like an old thin style lock nut and sits on top of the structural nut.
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Thank you! Having looked at the OP’s (interesting) link I was wondering if a circular spire nut is ever used professionally instead of a lock nut. The Palnut looks pretty much like one of those. They were in mind as I recently used – or misused! – one for extra security for a ratchet wheel on a square clock arbor, instead of drilling and pinning, and it worked very well. They are often used to hold bolts/screws in place in transit but I had not read of them as lockers.

I’m not sure what the formal definition of a ‘spire nut’ is – they and their names are very varied.
 
A large portion of humble pie for me please.
I was quite adamant in #29 that lock nuts were in use. Having recent occasion to revisit the installation and scratch an itch, it is indeed palnuts that are in use in all the structural elements.
 
RichardS said:
I've never heard of palnuts. :confused:

Richard
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Moderator said:
every day is a journey of discovery

https://duckduckgo.com/?q=palnuts&t=ffab&atb=v69-7&ia=web
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See my earlier post with a link to the Reliable Securing Handbook used by the offshore industry as part of the drive to reduce incidents from Dropped Objects.

Beware the small sizes on the steel version, the galvanising is terrible and it wears away rapidly to the point that the Palnut just corrodes and turns to dust when touched. If using in a marine environment, use the stainless versions.
 
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BlowingOldBoots said:
See my earlier post with a link to the Reliable Securing Handbook used by the offshore industry as part of the drive to reduce incidents from Dropped Objects.

Beware the small sizes on the steel version, the galvanising is terrible and it wears away rapidly to the point that the Palnut just corrodes and turns to dust when touched. If using in a marine environment, use the stainless versions.
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We use a lot of NORDLOCK washers offshore these days they are extremely good
https://www.youtube.com/watch?v=IKwWu2w1gGk
 
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