Patent ID: 8720616

Claim:
A wheeled object of the type adapted to be operated by a walking person and comprising: a main frame supported by a plurality of supporting wheels or rollers; a motor driven driving device comprising at least one driving wheel or roller engageable with a supporting surface for driving the wheeled object, the driving device being mounted so as to be rotatable about a substantially vertical axis in relation to the main frame so as to change an angular position and a driving direction of the driving device in relation to the main frame, said driving device being mounted on at least one supporting arm pivotably or rotatably mounted on the main frame or on a subframe about a common, substantially horizontal first axis so as to allow the driving device to move up and down around a single horizontal axis, the single horizontal axis being said first horizontal axis; and means for biasing the driving device in a direction away from the main frame and towards the supporting surface, wherein an axis of a motor driven driving shaft for driving the driving device coincides with said first axis.