Mechanical atherectomy and/or thrombectomy devices configured to remove obstructions (e.g., plaque material) of different consistencies and/or sizes from blood vessels. The devices may include a tractor comprising a flexible tube of material that inverts as it rolls over itself while being drawn into the open distal end of a catheter in a conveyor-like motion. The flexible tube can include features that facilitate engagement with the obstruction, enhance smooth tractor motion and/or promote movement control of the device within the blood vessel.