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The mechanical advantage is 2, requiring a force of only 50 N to lift the load. A block and tackle is characterized by the use of a single continuous rope to transmit a tension force around one or more pulleys to lift or move a load. Its mechanical advantage is the number of parts of the rope that act on the load. The mechanical advantage of a ...
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.
A single movable pulley has an MA of 2 (assuming frictionless bearings in the pulley). Consider a pulley attached to a weight being lifted. A rope passes around it, with one end attached to a fixed point above, e.g. a barn roof rafter, and a pulling force is applied upward to the other end with the two lengths parallel.
The two sections of chain carrying the single pulley exert opposing and unequal torques on the connected pulleys, such that only the difference of these torques has to be compensated manually by pulling the loose part of the chain. This leads to a mechanical advantage: the force needed to lift a load is only a fraction of the load's weight. At ...
As an example, using a block and tackle with six rope sections and a 600 lb load, the operator of an ideal system would be required to pull the rope six feet and exert 100 lb F of force to lift the load one foot. Both the ratios F out / F in and V in / V out show that the IMA is six. For the first ratio, 100 lb F of force input results in 600 ...
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 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 .
An illustration showing how pulleys are used to obtain a mechanical advantage. Using additional pulleys decreases the force required but increases the distance required to raise a load the same amount. In each instance here the mechanical work done is the same, work being the product of force and distance. F Z × s = F L × h 10 cm × 100 N = 10 J