Anyone know what this tool is used for?

Well you *do* know what the Hellerman sleeve fitting tool used to be called, don't you?

Circlip pliers?

My 25 year old ones have worn out. I somewhat balked when I looked up the price of a new set recently.

Circlip pliers to me of a sort

Yes, they're horribly expensive aren't they! I looked for some recently and even eBay didn't offer much at sane prices.

Can you make out the complete patent number? (seems to be a US Pat no)

Already tried that. I make it US Patent 81515, but the first and last numbers are very worn. Could be a 3 at the beginning, and there could be a number after the last 5. A patent search with that number didn't turn up anything, and I think it would have been quite an early patent at that, as it's surely a relatively low number as US patents go. Can't read the maker either.

I don't agree with the circlip pliers suggestions, because the jaw tips are surely too big for the eyes on a circlip. In addition, the springs are quite heavy duty, designed to pull the jaws closed, and the inner surfaces of the jaw tips are grooved, as if for gripping.

My money is on some sort of clamp.

Could be a tack/pin holder for carefully positioning short tacks before hammering in. I'd like a clearer close up of the tip to be sure.

Mike

A family member patented something in the late 1950s - US patent number

So is mine and possibly for somthing hot or heated by the discoloring of the grippy end. Two sizes of things as well, small rivets?

A close up pic of the jaws might help.

Actually, on looking at it again, it isn't a twitch, is it? What's the pressure on the jaws when it is closed?

Don't think so. A twitch wraps around a great chunk of the top lip, see

IMG_4110_zpsbc5094c0.jpg

From the picture it almost looks as if the springs can be slid toward the viewer, giving an option of sprung open or sprung closed. Is that so?

Mine might see more use if they had a smaller sized set of tips, but I haven't dared look for the price ...

I cant give any info re how it operates as not in my possession. Here a pic of the tip. At first thoug maybe for pinning in locks but too thick to access more than a couple of pins.

The number appears to be US Patent No. 01515 OR 015150. Regarding the circlip pliers theory theres no signs that any pieces have broken off of these, what ever they are:)

I though I had it, but turns out I hadn't.

and then there's this

I give up!

Are the lock pins connected to the pliers or is this just the use the present owner puts the device to

Without doubt. This particular pair for removing outer clips. There is a similar pair for removing 'inner' circlips.