Effect of Spring Pin thru Heavy Hex Nut 5

[bsmet95]

We are installing a monorail system with track switches. The switches will be hung with rods and braced against lateral movement. A hanger fitting will be used at each mounting point, with the rod and nuts as shown. Is there any problem with drilling thru the nut and inserting a pin?

Thanks.

 

[MintJulep]

Yes, there are.

But, why would you want to do that in the first place when there are so many better faster easier cheaper ways to prevent a nut from "backing off", whatever that may mean to you.

 

[bsmet95]

I would rather use a slotted hex nut but others wanted the spring pin method. Is there something other than a slotted hex nut that you can recommend?

Thanks.

 

[MintJulep]

Prevailing torque nut, either Nylon or all-metallic.
Loctite.

 

[Nescius]

All the textbook calculation stuff aside...

Drilling a nice, straight, and centered hole in the end of a springy rod, up in the air, may be a "big ask".

Removing that pin after a few years in the weather might turn into a party...seized pin in the end of a springy rod, up in the air.

 

[EdStainless]

I'll second MJ, prevailing torque nuts are the way to go.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[MintJulep]

Drilling a nice, straight, and centered hole in the end of a springy rod, up in the air, may be a "big ask".

Exactly.

 

[MikeHalloran]

Whoever 'wanted' to field drill and install spring pins have clearly never tried anything similar with their own hands.

Those persons should be removed from the design decision process immediately.



Mike Halloran
Pembroke Pines, FL, USA

 

[hydtools]

Consider bend tab washers.

Ted

 

[israelkk]

The safest are "lock wire nuts" they are used on aircraft machine guns against the worst vibration possible. Google for "lock wire nuts" you will find pictures. The nuts can be purchased already drilled for the use of lock wire.

 

[leeekim]

You could also consider Nord Lock washers. A sales guy told us they used these on the rail industry.

 

[chicopee]

Israelkk has the correct approach; safety wire on castellated nuts. Such work can be seen on aircraft propellers and engine mounts. It is time consuming to install and people doing the work have to be adept at such task.

 

[zeusfaber]

I'm struggling to remember seeing lockwire used on anything quite as big as 3/4" UNF.

A.

 

[SwinnyGG]

Castle nuts and lockwire-ready bolts do exist in those sizes, but they are very expensive. Several dollars per nut, without even considering the bolt that is required to match.

The spring pin method will likely be equally expensive when you have to hand drill every single nut and bolt in your assembly, assuming your assembly crew makes more than a few dollars per hour.

Tab washers, liquid threadlocking compound, and other methods will solve your problem. If it were me, stainless steel (or high strength, depending on loading conditions) prevailing torque nuts would get the nod.

 

[moon161]

I worked on a job for a French tire manufacturer. They were standardized on nord locks. If you go with a drilling the nuts, I'd pilot drill them in the shop.

http://www.nord-lock.com/nord-lock/wedge-locking/