tech training: Lock Washers

[OriginalOwner]

Here's a very fascinating video on the topic of Lock Washers.  When the intent is to prevent the nut from turning, this is a real eye-opener.  The tech dials in a shake table amplitude of 0.9 and I don't have the testing background to understand how severe that vibration is in terms of what we'all see in the real world.  But the results nonetheless give me a big reason to pay close attention to properly assembling a bolted connection.

 

 

Cheers,

 

Carl

[TobyB]

The 'music' sucks.

 

And I suspect the hardness of the surfaces has a huge effect on how well their proprietary lock washer works.

 

AND I was waiting to see how well threadlocker worked... and yes, wire and bent- plate, too...

 

Also, a wave washer...

 

Proves what Carroll Smith said about Nylocs, though- they're a lot better than a lock washer.

 

t

 

[jimk]

That test apparatus needs some explanation before I will accept any of the test results.   Besides, I've never seen an ad where the other guys stuff does better.

[Simeon]

Nord Lock nuts are used a lot in the rail industry for securing drive and detection rodding for switch machines and similar applications attached to the rails.

 

They also use a wide range of other proprietary lock nuts but never thread lock (correct process is hard to do and it's a harsh environment weather-wise). I think they like Nord Locks as they can be reused whereas most of the other systems are either similar to nylocs with aluminium in the nut or with a deformed section (like BMWs lock nuts). 

 

[TobyB]

You know, Carroll says Nylocs are reusable, as long as they are not damaged and have some drag left.

Likewise, the 'deformed barrel' nuts with the crushed threads.

 

I tend to replace them when it matters to me that the nut stays on...

 

I wanna try the nord locks- that's some fun with ramps, that is.

 

t

 

[Son of Marty]

When I got my airframe and powerplant FAA endorsement (more than a few years ago) the rule on lock nuts was once you engage the locking material if you can get more than 1/2 a turn by hand replace it.  

[TobyB]

What?  Something in the FAA replacement schedule makes sense???

 

hee

 

t

 

[bobthomas]

There was a fairly good article about lock washers in last issue of GRM or the issue before that.

[Tsingtao_1903]

Fascinating stuff.  I noticed the beginning of the video referenced DIN 65151.  It turns out that this spec has been superseded by DIN 25201.  The write up is in the link below.

 

http://vibrationmaster.com/useful-resources/standards/din-25201-—-important-new-standard-for-testing-fasteners/

[vacca rabite]

It may be overkill, but if there are bolts that CAN'T come loose (like CV bolts), I break out the wire and safety wire pliers and safety wire them together.

 

Zach

[JerryC]

They left out star washers as well.

 

I've disliked split spring washers (split-locks) for a long time. Ever since I started finding broken ones, and that they tend to gouge the screw head and the part being fastened.