A sheave () or pulley wheel is a
grooved wheel often used for holding a
belt
Belt may refer to:
Apparel
* Belt (clothing), a leather or fabric band worn around the waist
* Championship belt, a type of trophy used primarily in combat sports
* Colored belts, such as a black belt or red belt, worn by martial arts practiti ...
,
wire rope
Steel wire rope (right hand lang lay)
Wire rope is several strands of metal wire twisted into a helix forming a composite
'' rope'', in a pattern known as ''laid rope''. Larger diameter wire rope consists of multiple strands of such laid rope in ...
, or
rope
A rope is a group of yarns, plies, fibres, or strands that are twisted or braided together into a larger and stronger form. Ropes have tensile strength and so can be used for dragging and lifting. Rope is thicker and stronger than similarl ...
and incorporated into a
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 that ...
. The sheave spins on an axle or bearing inside the frame of the pulley. 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.
Adjustable pulley
A sheave can also refer to a pulley which has an adjustable operating diameter for use with a
mechanical belt. This is accomplished by constructing the pulley out of several pieces. The two main "halves" of the pulley can be moved closer together or farther apart, thus altering the operational diameter. The usual construction is some sort of locking collar or set screws to secure the components, one half with a threaded central shaft and one half with a threaded center. By rotating the components, one can "screw" the parts closer together or further apart, thus changing the distance between the two halves and allowing the belt to ride higher or lower in the groove. The adjustments are constrained to a specific range of sizes and are not limitless. One application of this is the
Variomatic automatic transmission.
See also
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References
Mechanical power transmission
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