Support device for semi-trailers supporting systems

The device has a reservoir unit (2) including a container chamber (22) and fixed to a supporting unit (6). The container chamber is opened at a supporting element (4), and a lubricant (8) is provided in the container chamber. The supporting element is moved relative to the supporting unit and to the reservoir unit along axial direction (A) in such a manner that the supporting element is retracted into the container chamber to stay the container chamber in contact with the lubricant. The container chamber includes a cross-sectional region transverse to the axial direction.