Self adjusting wrench

[john k]

Think there has been one like this pictured before.   No name or numbers.  In front of a 12 inch Crescent, that has been broken in two, and welded, still works.

[Plyerman]

Seems like those are often referred to as Cochran-style wrenches. There are several types pictured in this old Wrenching News auction:

http://www.wrenchingnews.com/ervin-auction-2008/catalog.html

Just scroll down to item 755 thru 771 and click on the PiC symbol.

[john k]

Thank you, some oil and the wrench works very well. 

[Plyerman]

Nice! It is a special one alright. And while looking that auction up I was surprised at how many companies made this type of wrench.