Coupling Torque Calculation

Core formula

Rated torque T = 9550 × P / n, where P is power (kW), n is speed (rpm), T in N·m. This is the most-used formula for coupling and gearbox sizing.

Rated vs peak torque

Rated torque is the continuous running torque; peak torque is the momentary maximum during start, e-stop or reversal. When selecting, rated torque should be ≥ 1.3× motor peak torque (service factor 1.3). For heavy shock, use 1.5–2.0.

Worked example

Motor 2 kW at 3000 rpm → T = 9550 × 2 / 3000 ≈ 6.4 N·m. With 1.3 headroom → need ≥ 8.3 N·m. Pick a model rated ≥ 9 N·m (e.g. CS-44+34.5).