That's not a ratchet, per se, elidas. It's a CAM-LOC ratcheting end wrench.
If you remove that drive plug, you'll find a series of spring-loaded rollers (cams) built into the interior aperture of the open end. You can use that particular wrench like a ratchet on any 1/2" hex fastener, 1/2" pipe, etc. They came in sizes from 3/8" to 1", usually in a roll-up. Patented in 1951, made originally by The Kramer Fabrication Company outside Detroit, and then made for or licensed to many others, including Snap-On (model numbers FW-12 through FW-32) in the 50's and 60's. Very popular in the US Army.
Here's a 7/8" model.
I've actually never seen that round drive plug adapter before. Very clever. It essentially turns a 1/2" ratcheting CAM-LOC end wrench into a 1/2" square drive ratchet.
Thanks for posting it.