- published: 13 Nov 2014
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A pulley is a wheel on an axle that is designed to support movement of a cable or belt along its circumference. Pulleys are used in a variety of ways to lift loads, apply forces, and to transmit power.
A pulley is also called a sheave or drum and may have a groove between two flanges around its circumference. The drive element of a pulley system can be a rope, cable, belt, or chain that runs over the pulley inside the groove.
Hero of Alexandria identified the pulley as one of six simple machines used to lift weights. Pulleys are assembled to form a block and tackle in order to provide mechanical advantage to apply large forces. Pulleys are also assembled as part of belt and chain drives in order to transmit power from one rotating shaft to another.
A set of pulleys assembled so they rotate independently on the same axle form a block. Two blocks with a rope attached to one of the blocks and threaded through the two sets of pulleys form a block and tackle.
A block and tackle is assembled so one block is attached to fixed mounting point and the other is attached to the moving load. The mechanical advantage of the block and tackle is equal to the number of parts of the rope that support the moving block.
A simple machine is a mechanical device that changes the direction or magnitude of a force. In general, they can be defined as the simplest mechanisms that provide mechanical advantage (also called leverage).
Usually the term refers to the six classical simple machines which were defined by Renaissance scientists:
A simple machine is an elementary device that has a specific movement (often called a mechanism), which can be combined with other devices and movements to form a machine. Thus simple machines are considered to be the "building blocks" of more complicated machines. This analytical view of machines as decomposable into simple machines first arose in the Renaissance as a neoclassical amplification of ancient Greek texts on technology, and is still a central part of engineering in today's age of applied science. For example, wheels, levers, and pulleys are all used in the mechanism of a bicycle. Between the simple machines and complex assemblies, several intermediate classes can be defined, which may be termed "compound machines" or "machine elements". The mechanical advantage of a compound machine is simply the product of the mechanical advantages of the simple machines of which it is composed.
Actors: Eugene Levy (actor), Steven Weber (writer), Jayne Eastwood (actress), Alan Alda (actor), Peter Riegert (actor), Steven Weber (producer), Boyd Banks (actor), Louis Di Bianco (actor), Jack Duffy (actor), Brad Garrett (actor), Harvey Atkin (actor), Steven Weber (actor), Sam Malkin (actor), Saul Rubinek (director), Ruth Secord (costume designer),
Genres: Drama,Actors: Yoram Globus (producer), James Hong (actor), Misha Segal (composer), Menahem Golan (producer), T.J. Castronovo (actor), Dale Ishimoto (actor), Sam Firstenberg (director), John LaMotta (actor), Jay Rasumny (actor), Shô Kosugi (actor), Randy Mulkey (actor), Ron Foster (actor), Steven Lambert (actor), Udi Harpaz (composer), Earl W. Smith (actor),
Plot: The body of a sexy aerobics instructor is invaded by the evil spirit of a dying ninja. At first, changes in her behavior is limited to having strange interactions with an arcade game, doing sexy things with V8 juice, and being attracted to an unusually hairy police officer. But soon enough, she's systematically killing, ninja-style, the officers responsible for the ninja's death, and can only be stopped by another ninja!
Keywords: b-movie, blood, blood-spatter, bo-staff, brawl, chase, chop-socky, cult-film, curse, death