I'm puzzled. I have a small brass barrel ready for a ship-type carriage and found a diagram in Round Shot And Rammers. The part that I don't understand is the "stool bed". Either it isn't in scale with the rest, or it ain't what I think it is. What is it just exactly, and where does it go? Hope someone can help clear it up. Thanks.
Cornbelt,
Max just about covers everything in his post; this type of ships and garrison trucked carriage was in use in Britain (and then in America) from circa the mid 1700's to circa the mid 1800's.
The stool bed is a shelf which usually sits between the reinforcing bolt placed through the middle area of the cheeks and the rear axle tree, it serves to support the quoin and the breech of the gun that is resting on the quoin.
This document doesn't have the best drawings I've seen but they're good enough to show you what the stool bed is. Scroll down to page 37: Fig. 3, K identifies the stool bed, p.38, Fig. 4 shows a stool bed and quoin from the side view, and p.39 gives a description of the stool bed. Scroll through the rest of the document, there are other helpful diagrams contained here.
http://www.nps.gov/fova/historyculture/upload/FOVA_389_D10_%5Bid279337%5D.pdf