as seen in fig2 a ball 48 can be dropped through the drill string to pass through the longitudinal bore 26 of the upper body 12 and come to rest at the upper end of the actuator plug 16 blocking the longitudinal bore 28 of the actuator plug 16 continued pumping of fluid through the drill string will build up pressure on the actuator plug 16 until it shears the shear ring 24 and moves downwardly to the lower position shown in fig2 when the tool is used with a downhole mud motor the drilling fluid pressure can be increased to a point which will shear the shear ring 24 without the necessity for dropping a ball in either case as the actuator plug 16 moves downwardly its conical lower surface 17 abuts and exerts downward and outward force on the angled inner edges 21 of the movable blades 20 this shears the shear pins 56 holding the movable blades 20 and moves the movable blades 20 downwardly and outwardly in their respective slots 19 this downward and outward motion can be either purely translational motion as shown in fig1 and 2 or it can have a rotational component the movable blades 20 can be prevented from falling out of their respective slots 19 by means such as abutting shoulders not shown on the blades 20 and slots 19 in this lower position of the actuator plug 16 the capture ring 40 snaps partially into the outer capture ring groove 46 in the lower body 14 and remains partially in the inner capture ring groove 41.