Patent ID: 7913782

Claim:
In combination, a self-propelled vehicle including a hitch and an output drive member, the self-propelled vehicle having a wheel base of a first distance; and a pull behind unit for attachment to the self-propelled vehicle, the pull behind unit including: a frame; at least two ground engaging members supporting the frame including a first, forwardmost ground engaging member, all of the ground engaging members being non-steering ground engaging members; a drive unit supported by the frame, the drive unit coupled to at least one of the ground engaging devices to power the movement of the at least one of the ground engaging members; a pull behind unit drive member coupled to an input of the drive unit and coupled to the output drive member of the self-propelled vehicle; and a pull behind unit hitch coupled to the hitch of the self-propelled vehicle, the pull behind unit hitch and the hitch of the self-propelled vehicle cooperating to define a hitch pivot point, wherein a second distance extending from the hitch pivot point to a rotation axis of the first, forwardmost ground engaging member is within a range from up to about 20 percent shorter than the first distance to up to about 50 percent longer than the first distance.