| Power and Torque Imperial Standards
Horsepower (HP)
Common unit of mechanical power, one HP is the rate of work required to raise 33,000 pounds one foot in one minute.
One Imperial Horsepower Equals
• 33,000 foot pounds per minute.
• 36 inch pounds torque at 1750 RPM.
• .746 Kilowatts.
• 1.014 Metric Horsepower. (PS)
• 42.4 BTU per Minute.
Torque (T)
Torque is a twisting force. Torque causes rotation of a shaft,  or it will set up a twist in a stationary shaft. It is generally expressed in foot pounds or in inch pounds. Torque is measured by the load or pull and by the distance of the pull from the center of a shaft.
Calculation Examples
A cable wrapped around a 6" dia. drum must lift a 2500 pound weight. The drum rotates at 30 RPM.
| To Calculate HP: |
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| To Calculate T: |
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Metric (SI) Standards
Power (P)
The basic unit power measurement in the metric (SI) system is the Watt. 1000 Watts = 1 Kilowatt (kW)
Torque (M)
Torque is a twisting force. Torque causes rotation of a shaft, or it will set up a twist in a stationary shaft. It is generally expressed in Newton-Meters. |
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| SI Symbols |
| M = Torque |
P = Power in Kilowatts |
| N = Newton |
Kfgm = Kilogram force meter |
| m = Meter |
N-m = Torque in Newton-Meters |
| • = Multiplication Symbol |
Calculation Examples
A cable wrapped around a .5 meter dia. drum must lift 5000 kilograms of weight. The drum rotates 50 RPM.
To Calculate P:
Power in Kilowatts |
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To Calculate M:
Torque in Newton-Meters |
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