Let-s see anyone knows what these are.

[KE4AVB]

[RoyM]

Lovejoy coupling used where the driving and driven shafts are not perfectly aligned.

[KE4AVB]

Nope, I designed them and had these made by my machinist before he retired. They are purpose made and I use them a lot. Kinda wish he was still working but I will another shop to make the one as I have ran into some that need a larger version.

[hanz63]

I stared at them for 5 minutes. I got nothin'.

[bgsengine]

I'd have to guess a socket wrench that slips over a shaft and engages a boss on the object being threaded on... I see the middle flats which would take a open end wrench, so...

[KE4AVB]

Pretty darn close. A 16mm impact socket up the hole the tighten a screw and the tool does engage a double "D" boss to prevent it from turning. The smaller one use a 1-1/2 open ended wrench to hold it while torquing the screw.

Much easier than finding someone to hold the other end. my arms are just not that long. Always having to find a way to do things when I by myself in the shop.

The tool covers four sizes of double "D" bosses. And I really need another one as I have some larger double "D" that have come since these were made..