Patent ID: 8091658

Claim:
A wheel arrangement for a four-wheeled vehicle, having capability of performing stationary turn of gyration, comprising: a vehicle frame having a front segment, a first vertical segment, a first middle segment, a second vertical segment, a second middle segment, a third vertical segment, and a rear segment, wherein said front segment, said first vertical segment, and said first middle segment are connected and adjacent to each other; said first middle segment connects to said second middle segment via said second vertical segment said second middle segment, said third vertical segment, and said rear segment are connected and adjacent to each other; and said first middle segment is lower than said second middle segment and said rear segment; a vehicle chassis positioned below and adjacent to said vehicle frame; a front wheel, coupled to the front segment of the vehicle frame, having abilities of driving and steering, wherein a steering angle of the front wheel toward one side is less than 90 degrees; two side wheels, coupled to opposite sides of said chassis, capable of rolling freely and individually while enabling the axis of the two side wheels to be aligned to a straight line without sharing a same shaft; and a rear wheel, coupled to the rear segment of the vehicle frame, capable of being turned and steered freely while being connected to a vehicle frame of the four-wheeled vehicle by a supporting base, wherein the rear wheel is rotatable within 360 degrees about the axis of the supporting base; wherein the front wheel, the two side wheels, and the rear wheel, remain in contact with the surface the vehicle rests upon at all times during normal operation; wherein the vehicle performs a turn-in-spot when the front wheel is turned such that the steering angle causes the vehicle to rotate in place about a point defined at the intersection of a longitudinal axis of the vehicle frame defined by a line going through the pivoting axes of the front and rear wheels, and a traverse axis of the vehicle frame defined by the collinear alignment of the axes of the two side wheels; and wherein the two side wheels are isometrically disposed at the opposite sides of the longitudinal axis of the vehicle frame so that the distance respectively measured from the front wheel to the two side wheels are equal and the distance respectively measured from the rear wheel to the two side wheels are equal.