It is used to connect two shafts whose axis are not in line with each one center block, two pins and two pins and two collars with lock pins. The forks are fitted with key on the ends of two shafts and then joined to a center block having two arms at 90 degree to each other. This coupling does the function on the action of its two pins. It does not work well if the angle between the two shafts is more than 45 degree.