An illustrative embodiment of the invention includes upper and lower anchoring members for temporarily securing a well tool in a well bore. The upper and lower anchoring members are pivotally supported from the central body member of the tool and respectively coupled to upper and lower movable slide blocks or driven pistons. The slide blocks are, in turn, moved by a two phase hydraulic transmission system whose pressure is controlled by a movable driving piston having two different cross sectional piston areas. The driving piston's motion is provided by a reversible electric motor via a gear box and threaded driving screw. This arrangement provides for low pressure fast moving initial deployment of the anchoring means followed by subsequent high pressure, low displacement anchoring force.