permits the enlarged end 68 a substantial degree of freedom without contacting the housing 70 or the base 32 this arrangement is best seen in fig2 the hydraulic check 64 includes a threaded stem 74 which has disposed thereon a pair of threaded members 76 and 78 a control arm 80 is secured to the rod 66 and slidably disposed along the threaded stem 74 the threaded members 76 and 78 permit the rod 66 to travel a predetermined distance prior to actuating the hydraulic check 64 the power cylinder 62 is air operated to provide rapid movement between the travel extremes such power cylinders are difficult to control at the end of their stroke the hydraulic check 64 provides a deceleration control at each end of the stroke of the power cylinder 62 the power cylinder will move freely and rapidly when the arm 80 is between the threaded members 76 and 78 however when the arm 80 engages either of these threaded members the added resistance of the hydraulic check 64 is imposed on the power cylinder 62 thus rapidly decreasing or decelerating its linear velocity a pair of limit switches 82 and 84 are also disposed on the mounting pad 60 to provide control signals to the pneumatic control for the power cylinder 62 the control of the power cylinder 62 is preferably electro pneumatic and of conventional design the workpiece mounting 18 is adapted to hold a workpiece such as a carrier 86 the carrier 86 is a conventional element which is used in a planetary gearing arrangement to support the planet pinion gears the carrier 86.