Here and in MANY other relic identification requests, reading/viewing the "right" relic refence book is the key to getting the Knowledge you want.
In this case, it is the 1907 mail-order catalog of horse equipment dealer J.M. Eilers & Co., who dealt in "horse and stable goods, harnesses, saddlery, and carriage trimmings." It contains hundreds of individual drawings of
each piece of horse and carriage equipment (like what Creskol posted), from the late-1800s up to its 1907 publication date.
I
think that catalog is where Creskol got the neck-yoke-tip diagram he posted. (If not, I hope will tell us which company's catalog he got it from.) Other useful second-half-of-the-1800s mail order catalogs are from Sears & Roebuck, and (for Military equipment) the Bannermann catalogs. You can buy modern reprints of those catalogs... and some are viewable for free online.
For example, you can view the hundreds of equipment drawings (with identification) in the 1907 Eilers horse & carriage equipment catalog, page by page, for free online, at the following link. It is a .pdf document, in a format that lets you turn the pages.
https://archive.org/details/catalogueno200jmei
Permit me to say:
Although I suspect many of you won't bother, every coin/relic digger here SHOULD spend at least an hour or two viewing the horse-harness & carriage equipment identification drawings in that 1907 catalog. I guarantee almost everybody will recognize several "mystery items" they've dug.