Patent ID: 8418986

Claim:
A movable supporting construction for placing on a floor comprising: a lower part and an upper part cooperating with said lower part, wherein the lower part is designed to rest on the floor and to assume a position that is determined by the condition of the floor, wherein a portion of the upper part comprises a conical element and a portion of the lower part comprises a spherical element, and wherein the upper part has a first and a second position, wherein in the first position, the upper part is suspended freely above the lower part against gravity but freely movable with respect to the lower part and in the second position, the conical element of the upper part rests on the spherical element of the lower part and is thus suspended against gravity by the lower part maintaining a predetermined invariant position by friction in the contact between the upper part and the lower part, wherein in the second position, the lower part and the upper part are in line contact, thereby determining a contact line that forms at least a portion of a closed line, wherein the upper part is brought from the first position to the second position by lowering; and wherein the upper part and the lower part are provided with connecting means for connecting the lower part and the upper part; and wherein the conical element is provided with an opening whose diameter is at least one and a half times the diameter of contact line.