Compare RV Reducer and Harmonic Reducer

Date: 2024-06-20　‖　Author：FuDong Machinery

There are two main types of reducers widely used in articulated robots: RV (Rotary Vector) reducers and harmonic reducers. So, which of the two reducer is more advantageous? What is the difference between the principle, advantages and disadvantages of the two? Can they replace each other? Let’s find out. 

Harmonic reducer is used for industrial robots with small loads, or several axes at the end of large robots, harmonic reducer for small robots is characterized by small size, light weight, large carrying capacity, high motion accuracy, and large single-stage transmission ratio. 

Harmonic reducer is one of the harmonic transmission devices, which include accelerators and reducers. The main structure of the harmonic reducer includes a rigid wheel, a flexible wheel, a bearing and a wave generator, all of which are indispensable. Among them, the number of teeth of the rigid wheel is slightly greater than the number of teeth of the flexible wheel. 

RV reducer is often suitable for robot joints with large torque, specifically the three joints of the legs, waist and elbows, and industrial robots with large loads, RV reducers are used in one, two and three axes. Compared with the harmonic reducer, the RV reducer has higher fatigue strength, stiffness and life, and the disadvantages of the harmonic reducer also include that with the increase of the use time, the motion accuracy will be reduced, and the advantages of the harmonic reducer are light in weight and small size, and the disadvantage of the RV reducer is that it is heavy in weight and large in size.

Both of them are less tooth difference mesh, the difference is that a key gear in harmonic is flexible, needs to be repeatedly deformed at high speed, so it is more fragile, so the bearing capacity and service life of the harmonic reducer are lower than that of the RV reducer, the bearing capacity is low, and the life is short. RV reducer generally uses cycloidal pinwheels, harmonics used to use involute tooth shape, and now some manufacturers use double arc tooth shape, which is more advanced than involute. 

Compared with the harmonic reducer, the RV reducer is a new transmission product, the RV reducer is actually developed on the basis of the traditional needle and thread reducer, which not only overcomes the shortcomings of the general needle pendulum transmission, but also has more advantages, such as long life, stable accuracy, high efficiency, smooth transmission, etc., small size, light weight, large range of speed ratio. 

As for the question of whether the two can be replaced, there are actually two theories.

1. First

It can be replaced, but only between some models. The RV reducer we have mentioned earlier has much higher fatigue strength, rigidity and life than the harmonic drive reducer commonly used in robots, and the return accuracy is stable, and the motion accuracy will not be significantly reduced like the harmonic transmission that uses the time increase. Therefore, RV reducers are mostly used in high-precision robot transmission in many countries, so there is a development trend, and RV reducers are gradually beginning to replace harmonic reducers in advanced robot transmission.

Harmonic reducers are characterized by being light and small, but in this regard, planetary reducers and RV reducers are difficult to do. Therefore, all kinds of reducers can only be replaced in some cases, but it is unrealistic to want one product to replace another product in an all-round way.

These products do have a substitution relationship in some models, but these types of reducers can only be partially replaced. In the vast majority of cases, various types of reducers are difficult to replace. 

2. Second

All kinds of reducers cannot be replaced, but can only complement each other. 

The two types of reducers, RV and harmonics, are complementary, but it is not excluded that after the optimization of structural design and the breakthrough of manufacturing process, local competition will be formed in some application fields. 

This is the comparison between RV reducer and harmonic reducer, the two can’t be said to be completely substituted for each other, and the functions and advantages of each reducer are very different, enterprises should integrate the use of robot joints and the different performance of the reducer, and choose a reducer product that is more suitable for the development of the enterprise.    -END-