What is the formula for torque from power and speed?

The formula is T = P × 9549 / n, where T is torque in N·m, P is power in kW, and n is rotational speed in RPM. The constant 9549 comes from 60000/(2π).

Why do we need a service factor for coupling torque?

Service factors account for dynamic loads beyond the steady-state nominal torque. Shock loads, cyclic variations, and starting torques can significantly exceed nominal values. The service factor ensures the coupling can handle peak loads without damage.

What is T = F × r and when do I use it?

T = F × r calculates torque from a tangential force F (in Newtons) applied at radius r (in meters) from the shaft center. Use this when you know the force acting on a lever arm, gear tooth, or coupling bolt circle.

How do I convert between N·m and other torque units?

Common conversions: 1 N·m = 0.7376 lb·ft = 8.851 lb·in = 141.6 oz·in = 10.20 kgf·cm. For kW to HP: 1 kW = 1.341 HP.

What service factor should I use for my application?

Uniform loads (fans, pumps): 1.0–1.5. Moderate shock (compressors, conveyors): 1.5–2.0. Heavy shock (crushers, mills, presses): 2.0–3.0+. Always verify with the coupling manufacturer's catalog for your specific application.

免費工程工具 #084

聯軸器扭矩計算器

使用 T = P×9549/n 根據功率與轉速計算軸扭矩。包含用於聯軸器選型的服務係數以及直接力應用 T = F×r。

T = P×9549/n T = F×r 服務係數

功率 (kW)

轉速 (RPM)

服務係數 (K_A)

快速預設

結果

設計扭矩（含服務係數）

—

額定扭矩

—

扭矩（lb·ft）

—

扭矩（kgf·cm）

—

角速度

—

來自功率與轉速的扭矩

常數 9549 = 60000 / (2π)，用於將 kW 和 RPM 轉換為 N·m。

含服務係數的設計扭矩

來自力與半徑的扭矩

其中 F 為單位為 N 的切向力，r 為單位為米的力臂。

服務係數表

K_A	負荷類型	被驅動機器範例
1.0	均勻負載	風機、離心泵、發電機
1.25	輕微衝擊	皮帶輸送機、鼓風機、輕型攪拌機
1.5	中等衝擊	往復式壓縮機、螺旋輸送機、容積式泵
1.75	重衝擊	球磨機、橡膠磨機、重型攪拌機
2.0	極重衝擊	破碎機、糖廠磨機、鋼鐵軋鋼機
2.5	嚴重正反向運轉	可逆軋鋼機、振動篩
3.0	極端衝擊	壓力機、剪切機、錘式磨機

提示： 當驅動機器（馬達）也具有脈動輸出（例如單缸引擎）時，將 K_A 乘以額外的馬達係數（通常為 1.25–2.0）。

範例 — 泵浦驅動

已知： P = 15 kW, n = 1500 RPM, K_A = 1.5

T_n = 9549 × 15 / 1500 = 95.5 N·m

T_設計 = 1.5 × 95.5 = 143.2 N·m