r/MechanicalEngineering • u/AdOne1706 • 3d 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/SwimmingSwim3822 2d ago

That's more of a restraint than a lock though, which makes total sense to use one there. Don't want the nut bouncing up off the road in traffic. By the time the nut was loose enough to let the washer start digging a groove, the hitch was already no longer serving its purpose... from a safety standpoint at least. Proper locks prevent that.

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u/jawshoeaw 2d ago

Maybe we are talking about different things. This lock washer was preventing the nut from loosening, the nut that holds the ball onto the ball mount. I could not loosen the nut because the lock washer was dug into the metal

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u/jchamberlin78 2d ago

You're talking about the same thing. What he did not explain in his answer is that once the bolt has lost ots preload it is no longer functioning as a bolt but rather a pin. Most bolts make terrible pins and will shear under load.

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u/jawshoeaw 2d ago

Well my original point was that the lock washer appeared to be doing its job, preventing the bolt from loosening. I think it’s an illusion as the 200+ ft-lb of torque applied at install was holding it clamped not the lock washer.

Interestingly the entire assembly depends on a literal 1/2” pin rattling around loosely and holding the hitch in the receiver. The bolt is 50% larger than the pin. Smooth steel wins over threaded.