stroke when the ball is being closed and is opened at the beginning of the operating stroke when the ball is being opened after shoulders 97 and 98 are engaged lower operating mandrel 92 will pull ball operating mandrel 96 upward thereby opening ball valve 47 the mandrels 78 and 92 will continue to move upward until faces 67 and 68 are engaged if the ball valve is fully opened before faces 67 and 68 are engaged or is fully closed before faces 74 and 75 are engaged slots 99 will allow ball operating mandrel 96 to deform sufficiently to prevent pins 112 from being pulled off of arms 104 weight and pressure responsive valve 24 is now in the open position allowing communication between the formation and the interior 6 of the testing string 10 tubular mandrel 31 moves in chamber 35 during a corresponding movement of operating mandrels 78 and 92 thereby absorbing these movements without affecting the testing string 10 above the slip joint 20 the weight and pressure responsive valve 24 operates responsive to a weight for the drill collars which has preferably been determined from the depth of the testing string the drilling fluid used the cushion fluid used and the dimensions of the drill collars it can be seen that the lifting force acting on the differential area of piston 44 responsive to the well annulus pressure may be divided into two parts the force generated in response to the hydrostatic pressure of the drilling mud and the force generated in response to the pump pressure added to the fluid pressure.