GB190922081A - An Improved Form of Electrically Operated Scenery Raising Gear. - Google Patents

Abstract

22,081. Moy, E. F., and Bastie, P. H. Sept. 28. Theatrical appliances.-In an electrically-operated device for raising and lowering theatrical scenery, two shafts a, a<1> are rotated continuously in opposite directions by means of an electric motor. Spur-wheels b freely mounted on the shafts are geared up with the grooved pulley f over which the lines e for lifting the scenery pass. Both the lines e and a hand rope j, which also passes round the pulley f, are secured to a counterweight h sliding in a guide fixed to the wall. The rope j enables any piece of scenery to be moved by hand if necessary. The spur-wheels b are engaged by friction clutches c which are operated by electro-magnets d, d<1>, a rocking bar x preventing both clutches from being operated at the same time. The magnets are controlled by a commutator switch m. Overwinding is prevented by limit switches q, which, when engaged by the counterweight, short-circuit the magnet windings and release the clutches. In operation, when the switch m. is closed, one of the spur-wheels b is clutched to one of the rotating shafts, and the scenery is raised or lowered until the counterweight closes a switch q and releases the clutch.