A new wellbore tractor system has been invented which, in one aspect has at least two slip units for alternately and releasably anchoring the system within a wellbore or within a tubular member and at least two movement units for moving an item in a wellbore, such as, but not limited to cable, tubing, casing, a tubular string or coiled tubing. In one aspect power strokes of the movement units overlap in time so that the system provides continuous motion. In another aspect a wellbore tractor system has been invented for moving an item through a wellbore, the wellbore extending from earth surface to an underground location, the system comprising a body connected to the item, first setting means on the body for selectively and releasably anchoring the system in a wellbore, first movement apparatus on the body for moving the body and the item, the first movement means having a first power stroke, and the wellbore tractor system for moving the item through the wellbore at a speed of at least 100 feet per minute. In another aspect such a system also has second setting apparatus on the body for selectively and releasably anchoring the system in the wellbore, the second setting apparatus spaced apart from the first setting apparatus, and second movement apparatus on the body providing a second power stroke for moving the body and the item, the second movement apparatus spaced apart from the first movement apparatus.