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Pulley
A pulley is a wheel on an axle or shaft that is designed to support movement and change of direction of a taut cable or belt, or transfer of power between the shaft and cable or belt. In the case of a pulley supported by a frame or shell which does not transfer power to a shaft, but is used to guide the cable or exert a force, the supporting shell is called a block, and the pulley may be called a sheave.
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.
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.
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Sheave
A sheave () is a pulley with a grooved wheel for holding a belt, wire rope, or rope. The grooved wheel spins on an axle or bearing inside the frame of the block. This allows the wire or rope to move freely minimizing friction and wear on the cable. Sheaves can be used to redirect a cable or rope, lift loads, and transmit power. The words sheave and pulley are sometimes used interchangeably.
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Pulley (noun)
One of the simple machines; a wheel with a grooved rim in which a pulled rope or chain will lift an object (more useful when two or more pulleys are used together, as in a block and tackle arrangement, such that a small force moving through a greater distance can exert a larger force through a smaller distance).
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Pulley (verb)
To raise or lift by means of a pulley.
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Sheave (noun)
A wheel having a groove in the rim for a rope to work in, and set in a block, mast, or similar; the wheel of a pulley.
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Sheave (noun)
A sliding scutcheon for covering a keyhole.
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Sheave (verb)
To gather and bind into a sheaf.
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Pulley (noun)
a wheel with a grooved rim around which a cord passes, which acts to change the direction of a force applied to the cord and is used to raise heavy weights.
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Pulley (noun)
a wheel or drum fixed on a shaft and turned by a belt, used for the application or transmission of power.
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Pulley (verb)
hoist with a pulley
“the tree house was built on the ground and pulleyed into the branches”
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Sheave (verb)
another term for sheaf (verb)
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Sheave (noun)
a wheel with a groove for a rope to run on, as in a pulley block.