SICHERHEITSSCHEIBE.

摘要

The screen has two rams located adjacent the panel of the screen, the rams being connected, at their one ends, symmetrically relative to the centre of the screen at or adjacent the top. At their other ends, they are connected relative to the screen. The points of connection of one of the ends are spaced by a spacing greater than the points of connection at the other of the ends to a structure beneath or beside the screen. The connections are such as to permit at least a degree of rotation of the rams relative to the panel and the structure. The arrangement is such that, as the rams are extended, the outward component of forces of the rams are equal and opposite, the resultant being an upward component which can drive the screen upwardly rapidly.