Pound-foot (torque)
pound-foot | |
---|---|
British Gravitational System, English Engineering Units | |
Unit of | Torque |
Symbol | lbf⋅ft, lb-ft |
Conversions | |
1 lbf⋅ft in ... | ... is equal to ... |
SI units | ≈ 1.355818 N⋅m[1] |
Gravitational metric system | ≈ 0.1382550 kgf⋅m |
A pound-foot (lb⋅ft), abbreviated from pound-force foot (lbf · ft), is a unit of
Unit
The value in
- One kilograms[1]
- Standard gravity = 9.80665 m/s2[1]
This gives the exact conversion factor:
- One pound-foot = 1.3558179483314004 newton metres.
The name "pound-foot", intended to minimize confusion with the foot-pound as a unit of work, was apparently first proposed by British physicist Arthur Mason Worthington.[3]
Despite this, in practice torque units are commonly called the foot-pound (denoted as either lb-ft or ft-lb) or the inch-pound (denoted as in-lb).[4][5] Practitioners depend on context and the hyphenated abbreviations to know that these refer to neither energy nor moment of mass (as the symbol ft-lb rather than lbf-ft would imply).
Similarly, an inch-pound (or pound-inch) is the torque of one pound of force applied to one inch of distance from the pivot, and is equal to 1⁄12 lbf⋅ft (0.1129848 N⋅m). It is commonly used on torque wrenches and torque screwdrivers for setting specific fastener tension.
See also
- Kilogram metre (torque)(kgf⋅m)
References
- ^ a b c d Butcher, Kenneth; Crown, Linda; Gentry, Elizabeth J. (May 2006), "The International System of Units (SI) – Conversion Factors for General Use" (PDF), NIST Special Publication 1038, archived (PDF) from the original on 2023-05-30
- ISBN 978-1111782382.
- ^ Arthur Mason Worthington (1900). Dynamics of rotation : an elementary introduction to rigid dynamics (3rd ed.). Longmans, Green, and Co. p. 9.
- ^ "Dial Torque Wrenches from Grainger". Grainger. 2020. In most US industrial settings, the torque ranges are given in ft-lb rather than lbf-ft.
- ISBN 978-1-4354-3933-7.