pressure from a source not shown may be introduced between operating ring 46 and the cover 54 which encloses the coupling retaining ring 46 contains an actuating pin 56 which is attached firmly to the actuating ring the shank portion 58 of this pin is aligned in slots 60 and 62 which are formed in the roller retaining ring and the third ring respectively as shown in fig3 these slots are formed at an angle to the rotational axis of the coupler further they are formed at opposite angles to each other with respect to the central axis the function of these slots will be explained in the operational description below there are provided between the third ring and the roller retaining ring locating balls 63 retained in grooves 65 and 67 for axially locating and restraining these rings as illustrated in the drawings the device is coupled together to cause shaft 12 to drive shaft 14 through the coupling device when the device is to be actuated and the shafts decoupled a working fluid usually hydraulic oil is introduced into opening 50 in the cover member 54 this fluid then passes along channel 52 and into chambers 64 on the back side of the actuating member 46 as the pressure of this fluid is increased the actuator 46 translates axially along axis a a compressing the spring 48 as the actuator translates the pin 56 acts upon the camming slots 60 and 62 to cause the roller retaining member 40 to rotate in one direction and the third ring 42 to rotate in an opposite direction as these members rotate with respect to each other the.