Retractable traction system

A system for retractably deploying enhanced traction of a wheel, the wheel having a tread and an axis of rotation, the system comprising:

• a set of grippers, each gripper having a cleat and a radially disposed strut;
• a set of first poles, each first pole coupled to one of the struts, each of the first poles configured to support motion of its corresponding strut between a parked position and an engaged position,
• wherein, in the engaged position of such strut, the corresponding cleat is axially disposed and engaged against the tread of the wheel and, in the parked position of such strut, the corresponding cleat is disengaged from the tread of the wheel;
• a first faceplate configured to rotate with the wheel, wherein, when such strut is in the engaged position, such strut is coupled to the first faceplate and moves with the first faceplate and the wheel, and, when such strut is in the parked position, the strut causes the cleat to be in a corresponding disengaged position, withdrawn in a radial direction from the tread;
• and
• a cleat deployment mechanism including:
• a second face plate rotatably coupled to the first faceplate and configured for rotation between first and second positions, and
• a set of second poles, each second pole coupled to a respective one of the struts and to the second faceplate, and configured so that rotation of the second faceplate between the first and second positions causes corresponding motion of each strut between the parked and engaged positions respectively.