What is it? CI

#583, Lock nut for use with a cotter pin. Or maybe and axle nut.

#585, Chain tensioner, for tightening down chains that hold loads.

581. I'm guessing a pipe or cylinder bore gauge designed to be used with the cylinder horizontal. The holder and tool would be slid into the cylinder so that the bottom edges of the holder rested along the bore. This would keep the tool perpendicular to the bore and exactly on a diameter. The tool can be adjusted until it's a sliding fit and then removed to read it either directly off its own scale for rough measurements or more exactly with a micrometer across the tool.

The way the mass appears to be distributed I doubt if it could be used easily with a vertical bore. It looks like it would just pivot over centre and the tool fall out unless you held the tool with one hand while inserting the whole thing with the other.

It looks a bit clumsy and much less accurate than a dial bore gauge or telescopic gauge so maybe it's nothing to do with bores at all and is for measuring a gap in some specific piece of machinery.

-- Dave Baker

Sorry, not true. You have the name right but the usage wrong. Slotted nuts are used on truck and automotive spindles, not Castellated nuts. There is a difference.

Nope, that's where slotted nuts are used. Not Castelated. There is a difference.

The only difference is that strictly speaking a castellated nut has a cylindrical section above the hexagonal part (as in the case of 583) and a slotted nut doesn't. I reckon most mechanics and engineers would automatically call both types a castellated nut though and be unaware of the somewhat pedantic difference.

Both types are designed for use with a split pin but the cylindrical part of a castellated nut makes it easier to wrap the split pin ends round the nut. Castellated nuts most certainly are used on automotive axles. You tend to see slotted nuts more on ball joints and other suspension parts. However probably the most common way of holding an adjustable type wheel bearing is a plain nut and the split pin goes through a pressed steel nut retainer which can be rotated to best line up with the split pin hole without altering the nut setting. The non adjustable wheel bearings tend to be torqued up to very high settings and a flange at the top of the nut is then staked into a notch on the axle so no split pin is used.

There's a pic of what is clearly a castellated nut on the wheel hub of a Vespa - all I could find online at short notice.

-- Dave Baker

It's going to be more of a rarity these days, seeing a castellated nut in an automotive situation. Heavy trucks still use a lot of slotted nuts and double nuts with lock rings. Ford came out with a spring loaded nut / washer assembly. There is no common way these days. Most manufacturers have gone to a sealed bearing hub with removable hats, although some of those hubs will have a slotted nut for the 4x4 axle. As for split or cotter pins, wrapping around the nut isn't always how it is to be done. Sometimes one leg will come back over the axle while the other might be cut or bent out of the way. Depends on the pin design.

Most mechanics would know the difference between the two nuts. They just won't care. If it came off, it goes back on.

So, yeah they were used. But not much these days. Somewhat like clutch head bolts and screws. When was the last time you seen one of those come out on a new product??

I suggest you consult a dictionary for the meaning of castellated, a hint, it has nothing to do with truck & automotive spindles.

Tom

Slotted

Oh I have a story about those, involving a boss's VW, a rear tire, a cotter pin, an intersection, and the front fender of an innocent SUV.

And it's wood related, because I was on summer break in college helping someone build their home.

er

I say potato you say pototo

Didn't I post that??

No, you posted something about "slotted" nuts which was entirely irrelevant.

According to Dave Baker :

I'm not sure about that. Would the thumbscrew be lifted up high enough to clear the slot, so it could rotate when the bottom edges of the holder were in contact with the cylinder walls?

[ ... ]

It is not *that* inaccurate. It is calibrated to 1/256th of an inch, or close to 0.004" per division. And it is quite old, as it has been a long time since machine work was done in fractional inches, so it may have been reasonable accuracy for the period.

Enjoy, DoN.

How's that?? The previous poster said that castellated nuts were used in automotive applications, steering and suspension. I said they are not ( similar to what you posted.) I said slotted nuts are mostly used in automotive applications. Spindles are part of automotive steering and suspension. Slotted nuts and castellated nuts are two different types of nuts. What part of that doesn't make sense to you?? Let me know and I'll explain it to you with pictures so you don't make the same mistake in the future.

The 'thumbscrew' doesn't want to lift above the slot. It's just a pin to stop the top of the tool rotating while the lower section is adjusted to size.

When I was trying to deduce what it was I took some measurements off the screen to ascertain the resolution of the device. Where it is marked 5 and

10 in the second pic you can measure the distance between those two points and also the diameter of the tool at the same place across the top of the conical bit.

You have to adjust for the fact that the distance between the 5 and 10 is a chord not an arc but I have a spreadsheet I often use which does that. The result is that the markings appear to indicate 25 divisions per revolution. Assuming each revolution is 1/16" then that's 1/400" (0.0025") per division but only every fifth division is marked. That's 12.5 thou per mark which is a country mile on an engine bore no matter how old. Maybe the OP could confirm what the resolution is for us.

I think the only way this could possibly be used to any accuracy is by measuring across it with a separate micrometer after gauging the bore.

-- Dave Baker

Let's clear this up a little . . . Doesn't really make a rat's backside whether it's slotted or castellated. They both serve the same function, which is to be retained in place by a cotter(or other) pin to keep them from coming loose. I spent a few minutes on Google Images, and in a lot of cases you'll be hard pressed to tell the difference. Search for slotted nut showed some that were apparently castellated according to your definition, and search for castellated nut showed some that sure looked like slotted. Technically they may be different, but for all practical purposes they're the same. Someone said the mechanic doesn't really care, if it came off it goes back on. Let's face it, you drop a handful of mixed slotted & castellated on a table most people aren't going to recognize the difference between them(or care).

is, in the 11th picture down, according to your definition, a slotted nut, but they call it a castellated nut. I believe Leon said "I call it potato, you call it pototo".

Next time I'll just keep my mouth shut.

Just for fun, OED says:

revolution.

I borrowed this tool from a cow-orker, so I don't have it with me but according to my notes it takes two full revolutions to go 1/16" of an inch. Although it doesn't appear so in the photos, the revolutions are broken down into 30 units, it's marked 0, 2-1/2, 5, 10, 15, 20, and then for some reason there is no marking for 25, just a blank space between 20 and 0. That's all that I can tell you about it right now.

Rob

Yes, please show us pictures of these "slotted" and "castellated" nuts, and explain the difference between a "castellated" and a "castle" nut, if you would be so kind. :-)

Thanks! Rich

Some young lady, singing to accompaniment, as if in an audition: "You say potato, and I say potato. You say tomato, and I say tomato. Potato, potato, tomato, tomato, let's call the whole thing off."

"You say pajamas, and I say pajamas, you say bananas, and I say bananas. Pajamas, pajamas, bananas, bananas, let's call the whole thing off."

"Um, I really don't see what's wrong with this relationship!"

Cheers! Rich