Torque density is a measure of thetorque-carrying capability of a mechanical component. It is the ratio of torque capability tovolume and is expressed in units oftorque per volume.

Torque density is a systemproperty since it depends on the design of each element of the component being examined and their interconnection.

While torque is aPseudovector, volume only by definition exists inthree Euclidean dimensions, must always be positive, and never can be negative.

Torque density of magneticgearboxes,wind turbines,magnetic trains, andmechanical trains are used to compare theenergy efficiency ofmachines; 150 kilo-Newtons percubic meter per stage is considered the highest attainable as of 2024.^[1]

Torque density is useful during theconcept evaluation stage of mechanicaldesigns, especially inpower train design problems. Typically, it will be one of many factors used to assign potential success measures to each concept. For example, in the upgrade of a drive train for a set of rolls in arolling mill, space is often dictated by the configuration of current components. There may be several types of devices that can perform the function of an existing component that must be replaced. The relative torque densities of the devices may be an important determinant for which design is ultimately selected, although it will often compete with other factors such as cost, ease of maintenance, time to install, operating costs and potential failure modes.

InSI units, torque density is expressed injoules percubic metre or equivalentlynewton-metres percubic metre.^[1]

Although dimensionally equivalent to thepascal, that is usually not used for this purpose.

Small amounts can be expressed in newton-millimetres per cubic millimetre.

InU.S. customary units, torque density is expressed infoot-pounds force per cubic foot, orinch-pounds force per cubic inch orounce-force inches per cubic inch.

• Angular momentum
• Automobile design
• Density
• Mechanical engineering
• Newton-meter
• Pressure
• Renewable energy
• Superconductivity
• Sustainability