Torque & Horsepower Information

Torque & Horsepower Equivalents


A turning moment or twisting effort that can be expressed in foot-pounds or pound-feet.


Foot-Pounds - A foot-pound is the amount of energy expended in lifting a one-pound mass a distance of one foot against the pull of gravity.

Foot-Pounds Indicates Energy

Torque (in Pound-Inches) = 63,025 x HP / RPM = Force x Lever Arm (in inches)
Torque (in Pound-Feet) = 5,252 x HP / RPM = Force x Lever Arm (in Feet)

  • Force = Working Load in Pounds
  • FPM = Feet Per Minute
  • RPM = Revolutions Per Minute
  • Lever Arm = Distance from the Force to the center or rotation in Inches or Feet

Pound-Feet - A pound-foot is the movement created by a force of one pound applied to the end of a lever arm one foot long.

Pound-Feet Indicates Torque


25 HP at 150 RPM = 875 Pound-Feet Torque
2.5 HP at 150 RPM = 1050.4 Pound-Inches Torque

Horsepower (HP)

A common unit of mechanical power. One HP is the rate of work required to raise 33,000 pounds one foot in one minute.

HP = Force x FPM / 33,000
HP = Torque (in Pound-Inches) x RPM / 63,025
HP = Torque (in Pound-Feet) x RPM / 5,252

Overhung Loads

A bending force imposed on a shaft due to the torque transmitted by V-drives, chain drives and other power transmission devices, other than flexible couplings.

Most motor and reducer manufacturers list the maximum values allowable for overhung loads. It is desirable that these figures be compared with the load actually imposed by the connected drive.

O.H.L. = 63,000 x HP x F / N x R

HP = Transmitted HP x service factor
N = RPM of shaft
R = Radius of sprocket, pulley, etc.
F = Factor

Factor (F) =

1.00 for single chain drives
1.10 for Timing belt drives
1.25 for spur or helical gear
1.25 for double chain drives
1.50 for V-belt drives
2.50 for flat belt drives

Weights of the drive components are usually negligible. The formula is based on the assumption that the load is applied at appoint equal to one shaft diameter from the bearing face. Factor F depends on the type of drive used. EXAMPLE: Find the over hung load imposed on a reducer by a double chain drive transmission 7 HP @ 30 RPM. The pitch diameter of the sprockets is 10", service factor is 1.3.

O.H.L. = (63,000) (7 x 1.3) (1.25) / 30 x 5

Manufactured in the USA by G&G Manufacturing Company.