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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.
In sailing, a block is a single or multiple pulley. One or a number of sheaves are enclosed in an assembly between cheeks or chocks. In use, a block is fixed to the end of a line, to a spar, or to a surface. A line (rope) is reeved through the sheaves, and maybe through one or more matching blocks at some far end, to make up a tackle.
The ideal mechanical advantage of the block and tackle is equal to the number of sections of the rope that support the moving block. In the diagram on the right, the ideal mechanical advantage of each of the block and tackle assemblies [7] shown is as follows: Gun tackle: 2; Luff tackle: 3; Double tackle: 4; Gyn tackle: 5; Threefold purchase: 6
A traveling block is the freely moving section of a block and tackle that contains a set of pulleys or sheaves through which the drill line (wire rope) is threaded or reeved and is opposite (and under) the crown block (the stationary section).
A gin pole in use loading logs. A gin pole is a mast supported by one or more guy-wires that uses a pulley or block and tackle mounted on its upper end to lift loads. The lower end is braced or set in a shallow hole and positioned so the upper end lies above the object to be lifted.
The general arrangement, using loops and turns in the rope itself to form a crude block and tackle, has long been used to tension lines and is known by multiple names. [2] [3] Knot author Geoffrey Budworth claims the knot can be traced back to the days when carters and hawkers used horse-drawn conveyances to move their wares from place to place ...
“You got all these people with this disease who need treatment,” he said. “There’s a medication that could really help us tackle this problem, help us dramatically reduce overdose death, and people are having a hard time accessing it.” The anti-medication approach adopted by the U.S. sets it apart from the rest of the developed world.
Crown block. A crown block is the stationary section of a block and tackle that contains a set of pulleys or sheaves through which the drill line (wire rope) is threaded or reeved and is opposite and above the traveling block. [1] [2]