Mechanical Design for the Stage

10

The Lifting Torque, T_lift

Overview

In theatre, moving scenery against the pull of gravity is common—it occurs in fly systems, in wagons run up and down raked decks, and with lifts hauling loads up out of the trap room. But all these moves are linear. Lifting during rotation is much less common, in part because set designers rarely ask for anything beyond a turntable on a flat floor. Occasionally though, a turntable on a raked deck is needed, or a draw-bridge-like movement, or maybe even a Ferris wheel. These effects will usually involve lifting against gravity via a torque about an axis of rotation, and that situation is the topic to be detailed in this chapter.

Lifting torque is somewhat unusual in that it can be described quite clearly with ...