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A dumb pulley can lift very large masses a short distance. It consists of two fixed pulleys of unequal radii that are attached to each other and rotate together, a single pulley bearing the load, and an endless rope looped around the pulleys. To avoid slippage, the rope is usually replaced by a chain, and the connected pulleys by sprockets.
A sheave or pulley wheel is a pulley using an axle supported by a frame or shell (block) to guide a cable or exert force. A pulley may have a groove or grooves between flanges around its circumference to locate the cable or belt. The drive element of a pulley system can be a rope, cable, belt, or chain.
A traveler curtain, also called draw curtain, bi-parting curtain, or just traveler, is the most common type of front curtain used in theaters. Traveler curtains remain at a fixed elevation and open and close horizontally, break up and meet in the middle, and consequently require a minimum of fly space .
Fly loft of the Theater Bielefeld in Germany. A fly system, or theatrical rigging system, is a system of ropes, pulleys, counterweights and related devices within a theater that enables a stage crew to fly (hoist) quickly, quietly and safely components such as curtains, lights, scenery, stage effects and, sometimes, people.
Diagram 3 shows three rope parts supporting the load W, which means the tension in the rope is W/3. Thus, the mechanical advantage is three-to-one. By adding a pulley to the fixed block of a gun tackle the direction of the pulling force is reversed though the mechanical advantage remains the same, Diagram 3a. This is an example of the Luff tackle.
Examples of rope and pulley systems illustrating mechanical advantage. Consider lifting a weight with rope and pulleys. A rope looped through a pulley attached to a fixed spot, e.g. a barn roof rafter, and attached to the weight is called a single pulley. It has a mechanical advantage (MA) = 1 (assuming frictionless bearings in the pulley ...
The blinds were often used instead of window curtains or shutters. In the 1840s, these blinds were held together by flat strips of cloth instead of by cords perhaps to shade the lift holes and like today they came in various colors. [2] In 1966, a new pulley system was invented which afforded great improvement in the control mechanism. [3]
Fly system: A fly system is a system of ropes, counterweights, pulleys, and other such tools designed to allow a technical crew to quickly move set pieces, lights, and microphones on and off stage quickly by "flying" them in from a large opening above the stage known as a fly tower/flyspace.