Hobson's Coupler

thingiverse

A Hobson's Coupler, or Hobson's Joint, is a mechanism designed to divert rotational power around a corner. Unlike a universal joint, it can function at an angle of 90 degrees and serve as a true constant velocity joint, but the angle remains fixed at construction time. I created these parts with simplicity in mind, allowing for easy experimentation. Three or more angled rods connect two rotating cylinders, resembling those found in revolvers. Each arm of a rod is free to slide and rotate within its chamber in the cylinder. The rods force the cylinders to rotate in sync with one another. As a rod moves closer to the point where the cylinders are nearest, both arms of the rod slide into their respective chambers. Conversely, as the rod moves further away, the arms slide back out. The mechanism primarily functions as a coupler in applications like the 90-degree Gearless Angle Drive, a ratchet/socket driver attachment by Cal-Van Tools. It is also used in certain shaft-driven bicycle designs. Additionally, it can function as an engine in its own right, with the rods acting as pistons, similar to steam or compressed-air powered Elbow Engines. The concept has been applied to the 1970s Bricklin-Turner Rotary Vee engine and other similar designs. Furthermore, it serves as the basis for the fictional V-Engine used in the mecha setting Heavy Gear.