Calculation

Selecting the Clutch Based on Maximum Torque

Selection criterion: Tkmax > Ts

Max. allowable coupling torque [Nm] Tkmax
Peak operating torque [Nm] Ts = TN · M · SZ · Sθ · SA
Rated torque1) [Nm] TN = P / (2 · π · n)
Rated transmission power [W] P (motor, machine, unit)
Rated speed [s⁻¹] n at the coupling
Mass factor2) [1] M = JG / (JG + JS)
Moment of inertia [kg·m²] JG of the uniformly rotating side
Moment of inertia3) [kg·m²] JS of the impact/vibration-inducing side
Start-up factor [1] S Z = 1.0 for Z ≤ 120
; SZ = 1.3 for Z ≤ 240
; SZ = 2.0 for Z > 240
Starts per hour [h⁻¹] Z
Temperature factor [1] S θ = 1.0 at −20 to +50 °C
S θ = 1.3 at +50 to +80 °C
S θ = 1.8 at +80 to +100 °C
Impact factor4) [1] S A = 1.5 for low…
SA = 1.8 for medium…
SA = 2.2 for high torque unevenness

Explanations

1) For motors, use the maximum torque instead of the rated torque (e.g., the overturning torque for electric motors).

2) Perform the calculation only if the drive side or load side exhibits non-uniform torque curves and induces torsional vibrations. Otherwise, M = 1

3) E.g., piston pumps and compressors.

4) Depends on the design of the drive or driven machines or units and on the type of load.

The factors listed are for guidance only; in special cases, please contact us for a quote. For coupling calculations, see also DIN 740