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In mechanical engineering, mechanical efficiency is a dimensionless ratio that measures the efficiency of a mechanism or machine in transforming the power input to the device to power output. A machine is a mechanical linkage in which force is applied at one point, and the force does work moving a load at another point.
A simple machine, such as a lever, pulley, or gear train, is "ideal" if the power input is equal to the power output of the device, which means there are no losses. In this case, the mechanical efficiency is 100%. Mechanical efficiency is the performance of the machine compared to its theoretical maximum as performed by an ideal machine.
The actual mechanical advantage (AMA) is the mechanical advantage determined by physical measurement of the input and output forces. Actual mechanical advantage takes into account energy loss due to deflection, friction, and wear. The AMA of a machine is calculated as the ratio of the measured force output to the measured force input,
A simple machine is a mechanical device that changes the direction or magnitude of a force. [1] In general, ... The mechanical efficiency ...
Energy conversion efficiency (η) is the ratio between the useful output of an energy conversion machine and the input, in energy terms. The input, as well as the useful output may be chemical , electric power , mechanical work , light (radiation), or heat .
So the mechanical advantage of an actual screw is reduced from what it would be in an ideal, frictionless screw by the efficiency . Because of their low efficiency, in powered machinery screws are not often used as linkages to transfer large amounts of power but are more often used in positioners that operate intermittently.
Watt's engine operated with steam at slightly above atmospheric pressure. Watt's improvements increased efficiency by a factor of over 2.5. [16] The lack of general mechanical ability, including skilled mechanics, machine tools, and manufacturing methods, limited the efficiency of actual engines and their design until about 1840. [17]
The mechanical advantage of a simple machine like the wheel and axle is computed as the ratio of the resistance to the effort. The larger the ratio the greater the multiplication of force (torque) created or distance achieved. By varying the radii of the axle and/or wheel, any amount of mechanical advantage may be gained. [18]