# Torque

Torque, abbreviated as \(\tau\) (Greek symbol tau) or T, also called moment of force, is a rotational moment. It is a measure of how much twisting is applied to a fastener. The units used to measure torque are in the form of force times length. Usually measured in newton-metres (Nm) if metric units are used or pounds feet (lb-ft) when imperial units are used.

## Torque formulas

\(\large{ \tau = r \; F \; sin \; \theta }\) | |

\(\large{ \tau = l \; F }\) | |

\(\large{ \tau = d \; F }\) | |

\(\large{ \tau = I \; \alpha }\) | |

\(\large{ \tau = \frac{ 5252\; HP }{ s } }\) | (engine horsepower) |

### Where:

\(\large{ \tau }\) (Greek symbol tau) = torque

\(\large{ \theta }\) (Greek symbol theta) = angle

\(\large{ \alpha }\) (Greek symbol alpha) = angular acceleration

\(\large{ d }\) = diplacement

\(\large{ F }\) = force

\(\large{ HP }\) = horsepower

\(\large{ l }\) = length, moment arm

\(\large{ I }\) = moment of inertia

\(\large{ P }\) = power

\(\large{ r }\) = radius

\(\large{ s }\) = speed (rpm)

## Breakaway Torque

The torque necessary to put into reverse rotation a bolt that has not been tightened.

## Breakloose Torque

The torque required to effect reverse rotation when a pre-stressed threaded assembly is loosened.