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A helical band actuator, generally known by the trademark Spiralift, is a complex and specialized linear actuator used in stage lifts and material handling lifts. The actuator forms a high-capacity telescoping tubular column (lifting capacities to 25,000 pounds, travel to 40 feet).〔Spiralift Specifications: http://www.galainfo.com/pdfs/spiralift3_eng.pdf〕 ==Raison d'être== Pierre Gagnon was awarded a US patent for the “Push Actuator” in 1989. Gagnon developed the actuator to substitute hydraulic cylinders in stage and orchestra lift systems. Hydraulic jacks were the predominant push actuators used in performing arts facilities, but they had their issues. The piston rods of a hydraulic lift extend below the platform they support by more than the length that the lift travels. For lifts at grade, housings for the rods are often sunk into support holes, known as caissons, that are inaccessible and often complicated by groundwater levels. If placed above ground, the space occupied by the rod housings is unusable. Gagnon’s actuator eliminates caissons and reduces the volume of unusable space below the platform of the lift. Another significant issue with hydraulic lifts is platform drift, the tendency of a platform to lower due to depressurization of the hydraulic system over time. Helical band actuators do not suffer from platform drift because they are rigid mechanical devices. Traveling nut screw jacks and rigid chain actuators can also be effective at addressing these issues with hydraulic jacks, and are also used for stage lifts. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Helical band actuator」の詳細全文を読む スポンサード リンク
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