Tow vehicle with anti-back up wheels

Claim 1

A tow vehicle for use in a tow system wherein a vehicle is mounted for movement in the direction of a guide slot, said vehicle comprising a base, front and rear pairs of wheels supporting said base, said base having a guide means at the front end thereof for selective entrY into a guide slot for guiding the base along the slot, said front pair of wheels being mounted for swiveling movement with respect to a generally vertical axis, said front wheels having brake means thereon for preventing the front wheels from rotating in a direction to cause the base to move rearwardly while the front and rear wheels are parallel to one another including rotatable clutch bearings surrounding the horizontally disposed shafts about which the front wheels rotate, each front wheel brake means including inner and outer races force-fit to the inner periphery of the rim on the front wheels, said bearings being cylindrical roller bearings in said races parallel to the axis of the front wheel shafts, the inner and outer races being constructed so as to enable the roller bearings to have a first position while the vehicle is moving in a forward direction and a second position when the vehicle is moving in a rearward direction, said outer bearing race having a tapered cam surface for preventing rotation of the roller bearings and front wheels in the second position of said bearings.