I. What is a harmonic speed reducer?
The earliest name for harmonic speed reducers was "strain wave gearing," which literally translates to "strain wave gear." After being commercially applied on a large scale by Harmonic Drive Systems, it was translated into Chinese as "harmonic gear transmission" after a second translation.
Harmonic reducers are important transmission components widely used in automation equipment, robots, precision instruments, and other fields. A harmonic reducer consists of three core components: a rigid gear, a flexible gear, and a wave generator. The wave generator, equipped with a flexible bearing, causes the flexible gear to undergo controllable elastic deformation, meshing with the rigid gear to transmit motion and power.
II. Planetary Gear Reducer
A planetary reducer is a widely used industrial product that reduces motor speed while increasing output torque. Planetary reducers are used as components in industries such as lifting, excavation, transportation, and construction. Since one set of planetary gears may not be sufficient for a large transmission ratio, sometimes two or three sets are needed to meet the user's requirements. Due to the increased number of planetary gears, the length of a two- or three-stage reducer will increase, and efficiency will decrease. Backlash: With the output end fixed, rotating the input end clockwise and counterclockwise until the input end produces ±2% of the rated torque, the reducer input end will have a slight angular displacement. This angular displacement is the backlash, measured in "minutes" (one-sixtieth of a degree). It is also sometimes called backlash.
III. What are the differences between harmonic reducers and planetary reducers?
Harmonic reducers and planetary reducers are two common types of speed reducers, and they differ significantly in structure, working principle, and application fields.
First, harmonic reducers and planetary reducers differ in structure. Harmonic reducers are designed based on the principle of harmonic gears and mainly consist of a drive wheel, flexible wheels, a composite wheel, and a rigid wheel. The flexible wheels transmit torque through friction, and the composite wheel undergoes elastic deformation, thus achieving speed reduction. Planetary reducers, on the other hand, consist of a sun gear, planetary gears, and an inner cam. The sun gear serves as the input shaft, the planetary gears are connected to the sun gear via a planet carrier, and the inner cam is located around the planetary gears; speed reduction is achieved through the rotation of the inner cam.
Secondly, harmonic reducers and planetary reducers operate on different principles. Harmonic reducers transmit torque through friction between the flexible gear and the composite gear, causing elastic deformation of the composite gear and thus achieving speed reduction. In contrast, planetary reducers achieve speed reduction through the interaction of the sun gear, planet gears, and an internal cam. The sun gear serves as the input shaft, the planet gears are connected to the sun gear via planet carriers and rotate around their own axes, and the internal cam achieves speed reduction by meshing with the planet gears.
Furthermore, harmonic reducers and planetary reducers differ in their characteristics and advantages. Harmonic reducers offer advantages such as compact structure, smooth operation, and high transmission accuracy, and can achieve large reduction ratios. However, harmonic reducers have relatively high manufacturing costs and are prone to problems such as elastic deformation and wear. In contrast, planetary reducers feature simple structure, high transmission efficiency, strong load-bearing capacity, and stable and reliable operation. However, planetary reducers have relatively small reduction ratios, making it difficult to achieve ultra-large reduction ratios.
Finally, harmonic reducers and planetary reducers also differ in their application areas. Due to their high transmission accuracy and smooth motion, harmonic reducers are widely used in precision machinery, industrial robots, aerospace, and other fields. Planetary reducers, on the other hand, are commonly used in industrial applications requiring high torque output, such as hoisting machinery, mining machinery, and metallurgical equipment, because of their simple structure and high load-bearing capacity.
In summary, harmonic reducers and planetary reducers differ significantly in structure, working principle, characteristics, and application areas. Understanding these differences will help in selecting the appropriate reduction gear for your application needs.
