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A block and tackle [1] [2] or only tackle [3] is a system of two or more pulleys with a rope or cable threaded between them, usually used to lift heavy loads.. The pulleys are assembled to form blocks and then blocks are paired so that one is fixed and one moves with the load.
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 ...
Cone pulleys and step pulleys (which operate on the same principle, although the names tend to be applied to flat belt versions and V-belt versions, respectively) are a way to provide multiple drive ratios in a belt-and-pulley system that can be shifted as needed, just as a transmission provides this function with a gear train that
V-belts need larger pulleys for their thicker cross-section than flat belts. For high-power requirements, two or more V-belts can be joined side-by-side in an arrangement called a multi-V, running on matching multi-groove sheaves. This is known as a multiple-V-belt drive (or sometimes a "classical V-belt drive").
(The two pulleys are joined together such that they rotate as a unit on the single shaft that they share.) The relative sizing of the two connected pulleys determines the maximum weight that can be lifted by hand. If the pulley radii are close enough, then the load will remain in place (and not lower under the force of gravity) until the chain ...
Tyrese Proctor scored 15 points and No. 6 Duke bounced back from its first loss of the season with an 86-35 victory over Wofford on Saturday, when the Blue Devils allowed their fewest points since ...
where is the angle (in radians) between the two flat sides of the pulley that the v-belt presses against. [5] A flat belt has an effective angle of α = π {\displaystyle \alpha =\pi } . The material of a V-belt or multi-V serpentine belt tends to wedge into the mating groove in a pulley as the load increases, improving torque transmission.
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