Power assist assembly for wheeled vehicles

An assembly for providing a direct frictional drive to the tread portion of a wheel on a vehicle, said assembly comprising:

• a) carrier means for contacting two rotatably mounted drive rollers laterally spaced with respect to each other at two separate locations against said tread portion for both drive rollers to frictionally drive said vehicle wheel to rotate about an axis of wheel rotation when said drive rollers are drivingly rotated,
• b) said drive rollers each having a longitudinal axis that is parallel to said axis of wheel rotation when the drive rollers are contiguous to the tread portion, and
• c) carrier mounting means for allowing automatic adjustment of the carrier means to effect movable alignment of the drive rollers to any back and forth movement of the tread portion in a first direction parallel to said axis of wheel rotation and further to any in and out movement of the tread portion in a second direction normal to said axis of wheel rotation to maintain substantially continuous frictional drive contact between the drive rollers and said tread portion, and
• d) drive means for rotating said drive rollers when said rollers are in said frictional contact with the tread portion to cause rotation of said vehicle wheel,
• e) said carrier mounting means is effective to shift about a first axis extending radially outwardly from said axis of wheel rotation and to pivot about a second axis extending in a direction parallel to said axis of wheel rotation while maintaining each of the drive rollers on opposing sides of said first and second axes with respect to each other when said drive rollers are in frictional driving contact with the tread portion.

An assembly for providing a direct frictional drive means for a wheeled vehicle having a vehicle frame whereby the drive means is in frictional contact with a vehicle wheel which includes a hub portion having a wheel axle, a rim portion, and a tire portion having a tread surface, said assembly comprising:

• a) an assembly frame structure including an upper frame portion, an upper drive roller carrier portion, and a lower wheel axle coupling portion for attaching the assembly to a hub portion of the vehicle frame,
• b) said upper frame portion is connectable to the vehicle frame and said drive roller carrier portion rotatably supports at least one drive roller in frictional contact with the tread portion,
• c) drive motor means is mounted to said drive roller carrier portion to rotate each drive roller when the motor means is activated,
• d) mounting means for pivotally connecting said drive roller carrier portion to said upper frame portion so that the drive roller carrier portion moves in response to a torque force created when the drive motor means is activated to effect camming movement of the drive roller carrier portion to urge the at least one drive rolller against the tread surface and in a direction opposite a direction of rotation of the vehicle wheel,
• e) said upper frame portion including camming movement limit means for contiguously disposing said at least one drive roller against said tread surface at a roller driving position for frictionally causing said vehicle wheel to rotate about an axis of wheel rotation, and
• f) power supply means for operating said drive motor means.