Image Number 4 for United States Patent #4382722.
The roof support according to the invention is between the roof-bar (2) and the sill piece (1) with at least one system of levers (3,4) connected by articulation with each other and connected by articulation with the roof-bar (2) and the sill piece (1) so that they have the form of a lying letter V directed with its vertex towards the fall. Between the levers (3,4) it is provided with the hydraulic cylinder (5) spragging the levers (3,4) and thus the lining. That admits to achieve a high multiplication of the cylinder travel in relation to the change of the lining height, and a multiplication of forces. In shield roof supports of a lemniscate type the lever system can consist of the fall shield (6) and the outside arm (7) of the lemniscate arrangement.