areas generates two opposing forces substantially balanced during relative movement application_number US 18159205 A description fig1 shows a cross sectional view of a simplified embodiment of the invention a tool 10 has an inner elongated member which includes a drive mandrel 50 a screw 62 and an engaging mandrel 66 the engaging mandrel may be a setting or a retrieving mandrel the drive mandrel 50 and the screw 62 are axially coupled for both rotational and longitudinal movement the engaging mandrel 66 and the screw 62 are preferably coupled for longitudinal movement only the cross sectional area of the drive mandrel 50 is substantially equal to the cross sectional area of the engaging mandrel 66 the tool 10 also includes an outer elongated member or main housing 64 the outside diameter of the main housing 64 is preferably constant fixed to the interior of the main housing 64 is a threaded component or nut 58 the nut 58 is threaded on the screw 62 one end of the main housing 64 is sealed to the drive mandrel 50 by a seal 48 the other end of the main housing 64 is sealed to the engaging mandrel 66 by a seal 70 the sealed interior of the main housing 64 is preferably equalized with the wellbore pressure the connection between the screw 62 and the nut 58 is not fluid tight i e chambers 65 and 67 on either side of the nut 58 are enclosed by the main housing 64 and are in fluid communication through gaps between the.