While working as an engineer for Ford Motor company, Alfred Hans Rzeppa created his constant velocity joint in 1926 and patented it the following year. The Rzeppa joint is a specific type of constant velocity joint—the ball and socket design involves 6 balls working with inner and outer races to transmit constant velocity torque from many different angles. Especially when the angle of the intersecting rotating shafts is expected to change frequently during service.
Each of the six balls rest in a separate grooves notched out of the shell on the end of the input shaft. These grooves guide the balls which are surrounded by a cage and then a star-shaped gear. This configuration all rests inside of a cup that is connected to a splined and threaded shaft.
Rzeppa joints are used in applications where even flexible shaft couplings would not have the misalignment capabilities needed. They can typically operate at angles up to 48° and sometimes even higher. The Rzeppa joint was initially designed for the automotive industry—this is still where they are most commonly found.