Stage types

Stages may be of different types as is presented below. In one gearbox there can be combined stages of different types.

Helical

Helical stage is presented in Fig.1. Gear ratios for helical gear stage can be in the range of 1,5...10. In DriveConstructor we narrow the possibility to choose from to 3...8. Efficiency of helical gear is high – usually between 97 and 98%. In DriveConstructor we assume rated efficiency of 98%. This type of gear is cheap to manufacture and has good torque and noise properties, though it is generally expensive and requires many gear stages for large reductions.

Fig.1. Helical stage. ¹ Fig.2. Worm gear. ²

Worm gear

Worm stage is presented in Fig.2. Gear ratios for worm stage can be from 5 and up extremely high ratios (100!). In DriveConstructor we narrow the possible to choose from to 10...40. Efficiency of worm gears goes down with the increase of the ratio (Fig.3). The possibility to have very high transmission ratios translates into greater cost-effectiveness. Also, worm gears typically ensure quiet, vibration-free operation. They are inherently a right-angle drive. Their typically low efficiency suggests their use for low or middle-to-low power demand applications and/or those featuring intermittent duty. They can be ideal for applications that need to resist reversing.

Fig.3. Efficiency of worm gear for different ratios.

Planetary gear

Planetary stage is presented in Fig.4. Gear ratios for planetary stage can be in the range of 3...10. In DriveConstructor we narrow the possibility to choose from to 4...8. Planetary gears can handle large reductions and give huge torque capability. They have high efficiency and are very compact. At the same time such gears are expensive to manufacture and can be noisy at high speeds.

Fig.4. Planetary stage. ³ Fig.5. Bevel stage. ⁴

Bevel gear

Bevel stage is presented in Fig.5. Gear ratios for bevel stage can be in the range of 1,5...4. In DriveConstructor we limit the choice to 2...3.

¹ Picture courtesy Emerson Power Transmission Corp ² Picture courtesy Emerson Power Transmission Corp ³ Source ⁴ Picture courtesy Emerson Power Transmission Corp