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An assembly of blocks with a rope threaded through the pulleys is called tackle. The process of threading ropes or cables through blocks is called "reeving", and a threaded block and tackle is said to have been "rove". [7] A block and tackle system amplifies the tension force in the rope to lift heavy loads.
A sheave or pulley wheel is a pulley using an axle supported by a frame or shell (block) to guide a cable or exert force. 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.
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 ...
The rope is threaded through the pulleys to provide mechanical advantage that amplifies that force applied to the rope. [ 4 ] In order to determine the mechanical advantage of a block and tackle system consider the simple case of a gun tackle, which has a single mounted, or fixed, pulley and a single movable pulley.
A dumb pulley can lift very large masses a short distance. It consists of two fixed pulleys of unequal radii that are attached to each other and rotate together, a single pulley bearing the load, and an endless rope looped around the pulleys. To avoid slippage, the rope is usually replaced by a chain, and the connected pulleys by sprockets.
A Z-Drag or Z-Rig is an arrangement of lines and pulleys, effectively forming a block and tackle, that is commonly used in rescue situations. [1] The basic arrangement results in pulling the hauling end 3 times the distance the load is moved, providing a theoretical mechanical advantage of three to one .
Pulleys can serve as a mechanical advantage, along with rope grabs, and other tools, to raise, or haul, a load up a vertical section, or across a gully or canyon. Pulleys systems are used in conjunction with the rope, rope grabbing devices, i.e.: Prusiks, or mechanical grabs, to capture the progress made during the lift. Since pulley systems ...
Sheave – Grooved wheel used to support a moving belt, wire or rope; Sheer legs; Sling (rigging) – Rope, webbing, wire or chain used to support a load for lifting; Rope splicing – Semi-permanent joint between two ropes; Tackle – System of two or more pulleys and a rope or cable; Tirfor – Device for pulling cable; Tugger (rigging)