A comprising: a) a frame; b) a seat attached to the frame; c) leg rests attached to the frame; d) a first pivot arm and a second pivot arm pivotably coupled to the frame; e) a first forward wheel on a first side of the frame and a second forward wheel on a second side of the frame; f) a first rearward wheel on the first side of the frame and a second rearward wheel on the second side of the frame; g) a first drive wheel on the first side of the frame positioned intermediate between the first forward wheel and the first rearward wheel and a second drive wheel on the second side of the frame positioned intermediate between the second forward wheel and the second rearward wheel; h) a first forward wheel actuator in operative connection with the first forward wheel to control a vertical position of the first forward wheel relative to the frame; i) a second forward wheel actuator in operative connection with the second forward wheel to control a vertical position of the second forward wheel relative to the frame; j) a first rearward wheel actuator in operative connection with the first rearward wheel to control a vertical position of the first rearward wheel relative to the frame; k) a second rearward wheel actuator in operative connection with the second rearward wheel to control a vertical position of the second rearward wheel relative to the frame; l) a first drive wheel actuator in operative connection with the first drive wheel to control a vertical position of the first drive wheel relative to the frame; and m) a second drive wheel actuator in operative connection with the second drive wheel to control a vertical position of the second drive wheel relative to the frame; wherein each of the first forward wheel actuator, the second forward wheel actuator, the first rearward wheel actuator, the second rearward wheel actuator, the first drive wheel actuator and the second drive wheel actuator is operable to independently control the vertical position of the first forward wheel relative to the frame, the vertical position of the second forward wheel relative to the frame, the vertical position of the first rearward wheel relative to the frame, the vertical position of the second rearward wheel relative to the frame, the vertical position of the first drive wheel relative to the frame and the vertical position of the second drive wheel relative to the frame, characterized by the first forward wheel being coupled to the first pivot arm and the second forward wheel being coupled to the second pivot arm, wherein the first forward wheel is outward of a first side of the leg rests, and the second forward wheel is outward of a second side of the leg rests that is opposite the first side of the leg rests. a) a frame; b) a seat attached to the frame; c) leg rests attached to the frame; d) a first pivot arm and a second pivot arm pivotably coupled to the frame; e) a first forward wheel on a first side of the frame and a second forward wheel on a second side of the frame; f) a first rearward wheel on the first side of the frame and a second rearward wheel on the second side of the frame; g) a first drive wheel on the first side of the frame positioned intermediate between the first forward wheel and the first rearward wheel and a second drive wheel on the second side of the frame positioned intermediate between the second forward wheel and the second rearward wheel; h) a first forward wheel actuator in operative connection with the first forward wheel to control a vertical position of the first forward wheel relative to the frame; i) a second forward wheel actuator in operative connection with the second forward wheel to control a vertical position of the second forward wheel relative to the frame; j) a first rearward wheel actuator in operative connection with the first rearward wheel to control a vertical position of the first rearward wheel relative to the frame; k) a second rearward wheel actuator in operative connection with the second rearward wheel to control a vertical position of the second rearward wheel relative to the frame; l) a first drive wheel actuator in operative connection with the first drive wheel to control a vertical position of the first drive wheel relative to the frame; and m) a second drive wheel actuator in operative connection with the second drive wheel to control a vertical position of the second drive wheel relative to the frame;