Actually the term shave tail comes from the practice of shaving a mules tail. First the top was shaved to denote a green broke mule,then another bell was added under it for mules that could be worked in harness, the 3rd bell was a mule broke to ride and drive. It carried over to raw recruits in the Calvary as they were designated as shave tail for being green. I could be mistaken in that 3 bells maybe meant they were rideable, packable, and driveable.
