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A simple crane. A counterweight is a weight that, by applying an opposite force, provides balance and stability of a mechanical system. [1] The purpose of a counterweight is to make lifting the load faster and more efficient, which saves energy and causes less wear and tear on the lifting machine.
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.
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.
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 ...
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. The earliest evidence of pulleys dates back to Ancient Egypt in the Twelfth Dynasty (1991–1802 BC) [1] and Mesopotamia in the early 2nd millennium BC. [2]
With a V angle of 90 degrees and offset crank pins, a V-twin engine can have perfect primary balance. If a shared crank pin is used (such as in a Ducati V-twin engine), the 360° crankshaft results in an uneven firing interval. These engines also have primary reciprocating-plane and rotating-plane imbalances.
The velocity v of the chain or belt is the same when in contact with the two sprockets or pulleys: v = r A ω A = r B ω B , {\displaystyle v=r_{A}\omega _{A}=r_{B}\omega _{B},\!} where the input sprocket or pulley A meshes with the chain or belt along the pitch radius r A and the output sprocket or pulley B meshes with this chain or belt along ...
Since the weight of the two cars is counterbalanced (except for the weight of passengers), no lifting force is required to move them; the engine only has to lift the cable itself and the excess passengers, and supply the energy lost to friction by the cars' wheels and the pulleys. [2] [6]