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Sheave without a rope. A pulley is a wheel on an axle or shaft enabling a taut cable or belt passing over the wheel to move and change direction, or transfer power between itself and a shaft. 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.
Within numerous science fiction settings, the challenges associated with contemporary cryonics are overcome prior to the development of faster-than-light travel, making it a viable means of interstellar transportation. In fictional renditions, the cells typically remain viable, and the revival process is depicted as straightforward or even ...
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.
Sometimes, a single rope was used to transfer power from one multiple-groove drive pulley to several single- or multiple-groove driven pulleys in this way. In general, as with flat belts, rope drives were used for connections from stationary engines to the jack shafts and line shafts of mills, and sometimes from line shafts to driven machinery ...
Many of the most enduring science fiction tropes were established in Golden Age literature. Space opera came to prominence with the works of E. E. "Doc" Smith; Isaac Asimov established the canonical Three Laws of Robotics beginning with the 1941 short story "Runaround"; the same period saw the writing of genre classics such as the Asimov's Foundation and Smith's Lensman series.
A time slip is a plot device in fantasy and science fiction in which a person, or group of people, seem to travel through time by unknown means. [12] [13] The idea of a time slip has been used in 19th century fantasy, an early example being Washington Irving's 1819 Rip Van Winkle, where the mechanism of time travel is an extraordinarily long sleep. [14]
An aerial tramway consists of one or two fixed cables (called track cables), one loop of cable (called a haulage rope), and one or two passenger or cargo cabins.The fixed cables provide support for the cabins while the haulage rope, by means of a grip, is solidly connected to the truck (the wheel set that rolls on the track cables).
The co-editor of the science fiction journal Extrapolation and a professor of English at the University of Georgia, Isaiah Lavender III, notes the usefulness of the dictionary for academic analysis of issues, saying "Having these origin dates in mind can help a student or scholar build a framework to analyze something like the concept of the ...