Definition of in KEPS Nut

I had a student ask me why a KEPS nut is called a KEPS nut today.
I have no idea. I know they are sometimes called K-nuts or washer nuts.
I looked on the web… can’t find an acronym or a definition
I had thought it might be a company or something…

Anyone have any insight into this.

We are just curious creatures…


A Keps nut, also called a K-nut or washer nut, is a nut with an attached, free-spinning washer. It is used to make assembly more convenient. The washer is commonly a star-type lock washer, though conical and flat washers are also used.

From Wikipedia.

Thanks but I knew that…
I want to find out WHY its called a “KEPS” nut


I just looked it up on google and didn’t find anything of interest. It could be the guys name who invented it or an abbreviation of his name. I don’t know.

KEPS is a trademark of Illinois Tool Works Inc. Apparently they invented the KEPS-nut. You might ask the what it means.

Their automotive groups seems to have a little info, But I did not find the answer to your question.


Ah Ha!

Fred gets a cookie. Since I know y’all will want further proof:

It KEPS the nut from coming lose.

Anyway it does not matter since Lock Nuts are better. :slight_smile:

Except that Keps Nuts are Lock Nuts. And if they are the nuts that I think you are thinking of you should not reuse them.

Maybe I should have said nylon lock nuts are better or at least I think they are.

And true its not a good idea to reuse them, but boy they don’t like coming lose.

and then there are the “PEM” nuts…

I emailed the ITW company and got this very nice response back quickly.

Prior to the invention of KEPS by the Shakeproof Division of ITW, nuts and washers were assembled by hand as separate components. Usually the washers were of the conical or tooth design. Invariably some washers would not get assembled causing a subsequent joint failure.

At the time, preassembly of the nut and washer into a single component was a major breakthrough in fastener technology. The assembled components not only provided the opportunity for improved automation, but assured that each fastened joint contained a washer. The trademark name KEPS was created by marketing as a short and easy to remember product name. Even today KEPS is a generic term for any pre-assembled nut and washer.

Pictures of various nut and washer assemblies may be viewed at:

Hopefully this brief history of KEPS is an adequate response for those curious students you teach. Best regards

Jim Anderson
ITW Shakeproof Industrial Products
Operations Manager

It was quite nice of them to take the time to inform us.

theirs not a day that i don’t wonder why people name things what they name them…:confused: