GB1312976A - Apparatus for controlling the movement and positioning of stage scenery - Google Patents

Abstract

1312976 Moving theatrical scenery HYDRAFLOAT STAGE SYSTEMS Inc 29 May 1970 26099/70 Heading A6M [Also in Division Fl] A device for moving theatrical scenery comprises a hydraulic or pneumatic cylinder 21 containing a piston with an endless cable 23 fixed to either end of the piston and also, by means of an anchoring device 24 which passes through a slit in the stage, to the piece of scenery to be moved. To drive the cable a fluid, preferably air, under pressure is supplied to one end of the cylinder via line 30 and released via line 31, or vice versa, under control of the valve 36 which is operated by solenoids 38, 39 and the valves 32, 33 which are themselves pneumatically operated by valve 44. In the neutral position (illustrated) the fluid supply 40 is connected to both lines but the valves 32, 33 are closed. Activation of solenoid 38 connects line 30 to the fluid supply and line 31 to the atmosphere and simultaneous activation of solenoid 45 opens valve 44 so that valves 32, 33 are opened and the piston is driven to the right. Activation of solenoids 39 and 45 has the reverse effect. To provide for even motion of the scenery, control valves 34 limit the rate at which fluid can leave either end of the cylinder to a preset value, while by-pass valves 35 allow an unrestricted flow into the cylinder at the high pressure end. Fig. 3 (not shown) illustrates a control circuit for the various solenoids also including a "limit switch" having a number of contacts which are successively activated by the movement of the scenery along its track so that selection of a particular contact causes the movement of the scenery to be halted when a pre-selected position is reached. A belt and pulley system driven by the cable 23 conveys the effect of the movement of the scenery to the limit switch.