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Bearing for harmonic drive

2022/01/23 05:32 USHGT

Harmonic drive, also called Harmonic Drive gear or a harmonic gear. It is a mechanical speed-changing device that reduces the gear ratio of a rotary machine to increase torque. It operates on a principle different from that of conventional speed changers. It is a planetary gear transmission that relies on flexible parts to generate elastic mechanical waves to transmit power and motion. Sometimes, the device is also called a harmonic reducer. Tags: bearing for harmonic gear, bearing for harmonic drive, bearing for harmonic reducer, flexible bearings for harmonic drive and Crossed Roller Bearing for harmonic reducer.

Three basic components of harmonic drive

As a reducer, the wave generator is usually active, the rigid wheel is fixed, and the flexible wheel is output.
The wave generator is a rod-shaped part, and its two ends are equipped with rolling bearings to form rollers, which are pressed against the inner wall of the flexible roller.

The flexible wheel is a thin-walled gear that can produce large elastic deformation. And its inner hole diameter is slightly smaller than the total length of the wave generator. The wave generator is a component that makes the flexible wheel produce controllable elastic deformation.

Mechanism of wave generator

When the wave generator is installed in the flex wheel, the cross-section of the flex wheel is forced to change from the original circle to an ellipse. The teeth near the two ends of the long axis are fully meshed with the teeth of the rigid wheel, while the teeth near the two ends of the short axis are completely disengaged from the wheel. The teeth of other segments on the perimeter are in a transitional state of engagement and disengagement.

When the wave generator rotates continuously in the direction, the deformation of the flexible wheel changes constantly. So that the meshing form of the flexible wheel and the rigid wheel also constantly changes. From meshing in, meshing out, disengaging, and meshing in again. It repeatedly does the slow rotation of the flexible wheel relative to the rigid wheel in the opposite direction of the wave generator.

The wave generator makes one revolution in the transmission process; the number of deformation cycles of a specific point on the flexible wheel is called the wavenumber, represented by n. Commonly used are two-wave and three-wave. The flexible wheel of the dual-wave transmission has less stress, a relatively simple structure, and it is easy to obtain a large transmission ratio. Therefore, it is currently the most widely used one.


1. High loading capacity. In the harmonic transmission, the meshing in and out of teeth is surface contact. The number of meshing teeth is relatively large simultaneously, so the load per unit area is small, and the bearing capacity is higher than other transmission forms.

2. Large transmission ratio. The transmission ratio of single-stage harmonic gear transmission can reach 70~500.

3. Small size and lightweight.

4. High transmission efficiency and long service life.

5. Smooth transmission, no impact, no noise, and high movement precision.

6. Since the flex wheel bears a large alternating load, the requirements for the fatigue strength, processing, and heat treatment of the flex wheel material are high, and the process is complicated.

Harmonic reducer is widely used in electronics, aerospace, robotics, and other industries; due to its unique advantages, the application in the chemical industry is gradually increasing.

The robot drive system requires a smaller clearance, higher stiffness, and higher output torque. And also a significant reduction ratio of the transmission system.

Common reduction mechanisms:

1) RV deceleration mechanism
2) Harmonic deceleration machinery
3) Cycloidal pinwheel deceleration mechanism
4) Planetary gear reduction machinery
5) No backlash deceleration mechanism
6) Worm gear reduction mechanism
7) Ball screw mechanism
8) Metal belt/tooth reduction mechanism
9) Ball deceleration mechanism

Rigid Bearing for Harmonic Reducer/Crossed Roller Bearing & flexible bearing

Crossed Roller Bearing for Harmonic Reducer with high rigidity,  rotation accuracy, and load-carrying capacity. This series bearing has a compact appearance, with mounting holes, customer can mount directly, suitable for every kind of harmonic drive. A preload applied to the rigorous approach before leaving the factory upon request.

CSD Series bearing (Integrated Inner Ring and Outer Ring)

SHG SHF Series Harmonic Reducer bearing (Integrated Inner Ring and Integrated Outer Ring) 

CSG CSF Series Harmonic reducer bearings (Integrated Inner Ring and Split Outer Ring)

The flexible bearing is mainly subjected to carrying the changing loads. Due to the thin wall of the bearing, a certain deformation occurs when the cam is matched. The inner and outer rings of the bearing and the rolling elements are made of high-carbon chromium bearing steel, and the general cage is made of an integral nylon cage.

Please get in touch with us at [email protected] regarding the bearings for a harmonic reducer, bearing for harmonic gear and flexible bearings for harmonic drive.

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