Mechanical efficiency measures the effectiveness of a machine

Machine (mechanical)

The mechanical properties of a machine manage power to achieve desired forces and movement. Modern machines often include computers and sensors that monitor performance and plan movement, and are called mechanical systems....

 in transforming the energy and power that is input to the device into an output force and movement. Efficiency is measured as a ratio of the measured performance to the performance of an ideal machine

Ideal machine

The term ideal machine refers to a mechanical system in which energy and power are not lost or dissipated through friction, deformation, wear, or other inefficiencies...

,

The efficiency of energy conversion of the power plant of a machine is often considered separately from the efficiency of the mechanism that transmits this power to achieve a particular force and movement.

Because the power transmission

Transmission (mechanics)

A machine consists of a power source and a power transmission system, which provides controlled application of the power. Merriam-Webster defines transmission as: an assembly of parts including the speed-changing gears and the propeller shaft by which the power is transmitted from an engine to a...

 system or mechanism

Mechanism (engineering)

A mechanism is a device designed to transform input forces and movement into a desired set of output forces and movement. Mechanisms generally consist of moving components such as gears and gear trains, belt and chain drives, cam and follower mechanisms, and linkages as well as friction devices...

 does not generate power, its ideal performance occurs when the output power equals the input power, that is when there are no losses. Real devices dissipate power through friction, part deformation and wear.

The ideal transmission

Transmission (mechanics)

A machine consists of a power source and a power transmission system, which provides controlled application of the power. Merriam-Webster defines transmission as: an assembly of parts including the speed-changing gears and the propeller shaft by which the power is transmitted from an engine to a...

 or mechanism

Mechanism (engineering)

A mechanism is a device designed to transform input forces and movement into a desired set of output forces and movement. Mechanisms generally consist of moving components such as gears and gear trains, belt and chain drives, cam and follower mechanisms, and linkages as well as friction devices...

 has an efficiency of 100%, because there is no power loss. Real devices will have efficiencies less than 100% because rigid and frictionless systems do not exist. The power losses in a transmission or mechanism are eventually dissipated as heat

Thermal energy

Thermal energy is the part of the total internal energy of a thermodynamic system or sample of matter that results in the system's temperature....

.

See also

• Mechanical advantage
  Mechanical advantage
  Mechanical advantage is a measure of the force amplification achieved by using a tool, mechanical device or machine system. Ideally, the device preserves the input power and simply trades off forces against movement to obtain a desired amplification in the output force...
  
  
• Thermal efficiency
  Thermal efficiency
  In thermodynamics, the thermal efficiency is a dimensionless performance measure of a device that uses thermal energy, such as an internal combustion engine, a boiler, a furnace, or a refrigerator for example.-Overview:...
  
  
• Electrical efficiency
• Internal combustion engine
  Internal combustion engine
  The internal combustion engine is an engine in which the combustion of a fuel occurs with an oxidizer in a combustion chamber. In an internal combustion engine, the expansion of the high-temperature and high -pressure gases produced by combustion apply direct force to some component of the engine...
  
  
• Electric motor
  Electric motor
  An electric motor converts electrical energy into mechanical energy.Most electric motors operate through the interaction of magnetic fields and current-carrying conductors to generate force...