Power – Torque – Speed

The basic relation of every rotating machine: power is torque times angular speed. Used for motor selection, gearbox checks and reading torque from a nameplate.

Power transmissionMotorUnits

Power P15.18kW

Power: 20.36 hp
Power: 20.64 PS (metric hp)
Torque: 10.2 kgf·m
Angular speed ω: 151.84 rad/s

METHOD

How it is calculated

P = T · ω      ω = 2π · n / 60
P[kW] = T[N·m] · n[rpm] / 9549
1 hp = 0.7457 kW      1 PS = 0.7355 kW

ASSUMPTIONS & NOTES

hp is mechanical (imperial) horsepower; PS is metric horsepower.
Motor nameplate power is shaft output; electrical input is that divided by the efficiency.

Results are for preliminary design and checking; base the final design on the governing standard and safety factors.

RELATED TOOLS

Machine Elements and more

Gear Ratio

Spur gear pair: ratio, output speed and torque, pitch diameters and centre distance.

Power transmissionSpur gearModule

V-Belt Drive

Belt length, drive ratio, wrap angle on the small pulley and belt speed.

Power transmissionBeltISO 22

Chain Drive

Roller chain: number of links, actual centre distance, sprocket pitch diameters and chain speed.

Power transmissionChainISO 606

Bolt Tightening Torque

Preload and tightening torque for metric bolts, with a VDI 2230 equivalent-stress check.

FasteningVDI 2230ISO 898-1

Shaft Diameter

Minimum solid shaft diameter under combined bending and torsion (ASME shaft code), with a standard size.

ShaftTorsionASME

Parallel Key

DIN 6885 key size, hub bearing-pressure and key shear checks, and the minimum key length.

Shaft-hubDIN 6885Bearing pressure