Battens system for raising and lowering sceneries or similar loads on a stage

摘要

A battens system for raising and lowering sceneries or similar loads on a stage is disclosed. The system comprises a series of support members adapted to be secured to the joists of a ceiling, an elongated winch drum made up of several sections interconnected by universal joints and supported in horizontal position by said support members, each winch drum section being provided over part of its length with a helical groove on which a cable for supporting the load is wound. Each support member carries bearing wheels engaging the helical grooves for rotatably supporting the winch drum and for causing its axial displacement at each turn by a distance equal to the pitch of the cable wound or unwound from the winch drum, such that the load will not be laterally shifted when being raised or lowered. The shaft of a reversible hydraulic motor is secured to an end of the winch drum, whereby the hydraulic motor moves with the winch drum in its axial movement. The housing of the hydraulic motor is provided with a torque arm engaging a stationary guide extending parallel to the winch drum to prevent rotation of the motor housing. The hydraulic motor is controlled by a three-position spool valve, the position of which is controlled by a reversible electric stepping motor. Movement differential between the stepping motor and the winch drum produces progressive closing and opening of the valve which results in smooth acceleration and deceleration of the load during raising or lowering, and an accurate positioning of the load. A brake is preferably provided to stop the winch drum when the hydraulic motor is not supplied with fluid under pressure.