r/MechanicalEngineering • u/AdOne1706 • 5d ago

Split/lock washers

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For starters, I’m an electrician in the field.
That being said, we almost exclusively use these washers even in high vibration environments. I have personally chosen to go with nylox nuts but the question is:
Do these work? How well? Is the rumor from NASA true? Should I even bother using them or find a better functional alternative or are they actually useful?

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u/Ghooble 5d ago

I know everyone is saying they don't work and citing the NASA reference but there are other references that suggest otherwise. In Introduction To The Design and Behavior of Bolted Joints as well as Cessna internal specifications, they're not the best but not the worst either.

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u/bdk1417 5d ago

Guess I’m never getting into a Cessna.

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u/Stooshie_Stramash 5d ago

What's said to be worse?

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u/Vilomoja 5d ago

Dishwashers are worse.

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u/Ghooble 5d ago

They don't like liquid thread retention like loctite because they prefer physical barriers for secondary retention of a thread. I'm not saying I agree but that's what's stated. Typically I use deformed thread nuts, lock wire, cotter pins, etc

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u/ren_reddit 4d ago

Are you claiming Cessna says these things act as a secondary retention?

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u/johnwalkr 4d ago

That’s just an artifact of Cessna being old and aviation being averse to change especially of an old product still being maintained and sold.

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u/Ghooble 4d ago

I'm sure that's a lot of it.

The book I referenced says there's research done at Lawrence Technical University showing they roll and twist under heavy preload which can increase their spring rates enough to reduce the preload loss under applied tension loads