Hello, jabberwocki and skip . I think that profile  is called  a fuller. And I agree that it is a struck tool!

not a hammer, its a "struck piece" used by blacksmiths  your apprentice holds it by the handle and you whack it with an actual hammer.

Not sure what this particular one does

Skip

You see, THIS is why I always bring my tool questions here! I would have never guessed this wrench was part of a set of tools for a Packard (USA) built Rolls-Royce Merlin engine for a P-51 Mustang in 1942-1943. Thanks Don for the info and pic. The collective knowledge on this site is staggering, you guys are awesome.

I've got a reprint of a Stanley Rule and Level Company catalog that lists it.  It doesn't describe what it's for, but does mention that the roller is there to reduce strain on the workman's wrists, implying to me that the workman in question is above the tool and leaning over it, which would mean floor scraping.  Also, the handles are removable for working into corners, for what that's worth.

They also don't describe what the #80 is for, although the #81 is called out as a cabinet scraper.  Some of the scraper planes are called out as cabinet tools; others as veneer scrapers.

It's interesting how many variations of scrapers the manufacturers made back in the late 19th/early 20th century, some of which survived quite a while.  I'm not sure the #83 was a cabinet scraper; it could have been a floor scraper.  Hardwood floors were customarily scraped both after installation and as part of refinishing, and Stanley made several scrapers for that purpose, in addition to cabinet and other scrapers.

Then sanders powered by electrons rather than sweat came along, and scrapers become much less critical, although some, like the #80 Stanley cabinet scraper, survived a long time because they were very useful tools.  Although Stanley's stopped producing them, there are still companies out there making versions of this particular tool.