| 1Define the required motion | Output speed, direction change, rotation angle, and duty cycle | Gear ratio: i = nin / nout For a standard right-angle bevel gear set, the shaft angle is commonly 90°. | Confirm whether the mechanism needs continuous rotation, intermittent indexing, reversing motion, or a fixed speed reduction before selecting the gear geometry. | 1,800 rpm input and 600 rpm output requires a nominal ratio of 3:1. |
| 2Match the gear ratio | Tooth counts on the pinion and gear | Ratio: i = z2 / z1 A 20-tooth pinion driving a 60-tooth gear produces 3:1. | Use compatible tooth systems and avoid an excessively small pinion. A larger pinion tooth count generally improves tooth strength and reduces undercutting risk. | z1 = 20, z2 = 60, giving i = 3.00. |
| 3Size for torque | Transmitted torque, power, and rotational speed | Torque from power: T(N·m) = 9550 × P(kW) / n(rpm) Select a service factor for shock loads, starts, and operating hours. | Calculate torque at both shafts and verify the gear rating under the actual duty cycle. The output torque increases approximately with the ratio, reduced by transmission losses. | For 2 kW at 1,800 rpm: T ≈ 10.6 N·m before applying the service factor. |
| 4Choose the correct gear size | Module, pitch diameter, face width, and center distance | Pitch diameter: d = m × z For module m = 2 mm and 20 teeth, d = 40 mm. | A larger module and suitable face width increase load capacity, but also raise size, mass, and inertia. Check the available housing space and shaft spacing. | With m = 2 mm: pinion pitch diameter = 40 mm; 60-tooth gear pitch diameter = 120 mm. |
| 5Check speed and motion quality | Pitch-line velocity, noise, vibration, and acceleration | Pitch-line speed: v = πdn / 60 where d is in meters and n is in rpm. | Higher speed increases sensitivity to tooth accuracy, balance, lubrication, and alignment. Use precise tooth geometry and controlled backlash when smooth, low-noise motion is required. | For a 40 mm pitch diameter at 1,800 rpm: v ≈ 3.77 m/s. |
| 6Select material and heat treatment | Strength, wear resistance, temperature, and corrosion exposure | Common engineering choices include case-hardened alloy steel for high load capacity, through-hardened steel for moderate duty, and stainless steel where corrosion resistance is important. | Match the material to torque, speed, lubrication, ambient temperature, and contamination. Surface hardening can improve wear resistance while retaining a tougher core. | A high-cycle, shock-loaded drive generally needs a stronger and more wear-resistant material than a lightly loaded positioning mechanism. |
| 7Verify installation and maintenance needs | Backlash, shaft alignment, lubrication, sealing, and mounting accuracy | Check the specified backlash and ensure the shaft angle and mounting distance remain within the gear designer's tolerances. Use suitable lubricant viscosity for the operating speed and temperature. | Incorrect mounting distance or shaft misalignment can concentrate contact at one tooth edge, causing noise, pitting, and premature failure. Plan inspection and lubrication access from the start. | Before commissioning, confirm tooth contact pattern, backlash, fastener security, lubricant level, and abnormal vibration or temperature. |