Locknut use? 2

[fpm]

I have an application where a component is positioned using a nut tightened onto a threaded rod. The rod, which is prt of the component, passes through a plate,and the component is positioned vertically via the position of the nut on the threaded rod.

The application is prone to high ambient temperatures, and lots of vibration.

Previously we had used nylok nuts, but these were working loose, allowing the component to work itself to a new (bad!) position.

Now considering 2 locknuts, or loctite (or similar)...I has been thinking of lockwashers, but having spent the last 30 minutes reading about their general uselessness, I've rethought...

Any suggestions on what might be the best course of action?
Thanks
FP

 

[MikeHalloran]

French locks, or "Stage 8" nuts:

http://www.stage8.com/

Mike Halloran
NOT speaking for
DeAngelo Marine Exhaust Inc.
Ft. Lauderdale, FL, USA

 

[fpm]

Thanks Mike,
Had a look at Stage 8, but I don't see it working as I haven't got any suitable surface to brace the 'wrench' part of their system against.

I found

http://www.locknuts.com/pn-loc.html,

anybody have experience of these?

 

[CoryPad]

There are high temperature adhesives available. Try Loctite and 3M.

Regards,

Cory

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.

 

[maytag]

FPM,we do a lot of steel mill applications with Superbolt hardware for the larger components. Smaller ,concritical parts are mostly secured with red Loctite. Maytag

 

[alexit]

Depending on rod size, check out Spieth locknuts...

 

[fpm]

Rod size is M8x1.25.
Thanks all for the input so far!

 

[Tmoose]

Does the component only have a nut on one side ?

Or a nut on each side, like in example A shown here -

http://www.kuleuven.ac.be/bwk/materials/Teaching/media/wg12/f0600014.jpg

 

[borjame]

Try eliptical nuts, they're deformed out of round so that when you use them there's an extra load that keeps them tight. However, unless you use a mechanical fastener some vibrations will always loosen the nut. In the good old days they used lockwire to hold nuts in place, it fell out of favor b/c of 1)safety 2)pain in the butt to apply and remove.

 

[BillPSU]

Double nutting and using adhesive should solve your problem but if it does not then a self locking thread like a dardelet thread can be used.

 

[MikeHalloran]

I'm thinking you could use a special Stage 8 'wrench', with the tab narrowed a bit, bent to parallel the rod axis, and projecting into a drilled hole or similar feature, also parallel to the rod axis. If you can't justify the tooling cost, French locks are cheaper.





Mike Halloran
NOT speaking for
DeAngelo Marine Exhaust Inc.
Ft. Lauderdale, FL, USA

 

[fpm]

Thanks again for all the advice.
I only stumbled across this forum yesterday...boy am I glad!

Theres a nut on one side only, and each component actually has 4 rods/nuts holding it in position, and there could be anything up to 50 components in an assembly, so the simpler and quicker the solution is, the better. But then ain't that the way...

Lockwire would be perfect, but would be too time consuming for the number of nuts involved.

Thanks
FP

 

[bugnut]

I do not know of a source but there are locknuts made that do not use a nylon or secondary mechanical device. These are made by dimpling 3 of the outer edges and are used extensively in the lawn mower and yard implement manufactured. They have a dimple on three of the side, which I surmise is to cause a pinching of the thread. These do not come loose in vibration and heat. Might check Thomas Register for a nut manufacturer or call a couple local suppliers.

 

[fpm]

I've come across these...

http://www.lok-mor.com/cap-loc.html

Anybody any experience of them?

 

[bugnut]

FPM great site-the nut I described is shown as HEX-LOC® Reversible Locknut these are used in MANY lawn equipment applications-Thanks for the name!!

 

[zekeman]

How about, the old reliable castellated nut, which is the most positive locknut you can get, since when applied properly cannot allow the nut to rotate beyond the lash in the fit, thus making it impossible to rotate out.