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  • Writer's pictureSyed Sagheer Abbas Rizvi

Planetary, RV, and Harmonic Reducers: What They Are Different From

Updated: Dec 26, 2022

In the market today, there are many different types of reducers that are often utilized, including planetary reducers, RV reducers, and harmonic reducers. Now, a Wanfu engineer will explain how these three varieties of reducers differ from one another.

Planetary Reducer

The planetary reducer is an item used in industry. A transmission device is a planetary reducer. On the gearbox housing, lead screw an inner gear ring and its structure are securely incorporated. An externally powered sun gear is located in the center of the ring gear. A planetary gear set with three evenly spaced and combined gears on a tray is located between the two.

When the input side power drives the sun gear, the planetary gear can be driven to spin and circle along the center, following the trajectory of the inner gear ring. The planetary gears depend on the output shaft, internal gear ring, and sun gear support. The output shaft that is attached to the tray is driven to output power by the planet's rotation.

A system that uses gear speed converters to increase torque by reducing the number of motor (motor) rotations to the necessary amount. lead screw The planetary reducer is a precision reducer utilized in the mechanism of the reducer that transmits power and motion.

RV Reducer

An innovative sort of transmission is the RV transmission. It was created using the foundation of conventional planetary pin-vibration transmission. It not only improves upon the drawbacks of conventional pin-vibration transmission, but has also drawn considerable attention due to its small size, lightweight, wide transmission ratio range, long life, steady accuracy, high efficiency, lead screw smooth transmission, and other advantages.

A cycloidal pinwheel with planetary support makes up the RV reduction. It is widely used in industrial robots, machine tools, medical tests, equipment, satellite receiving systems, and other fields because of its small size, strong impact resistance, huge torque, high positioning precision, low vibration, and many other advantages.

It has far higher stiffness, life, and fatigue resistance than the harmonic drive that robots often use, and the accuracy of the return difference is stable.

Most high-precision robot transmissions use RV reducers because, unlike the harmonic drive, the motion accuracy will be greatly diminished with the prolonged operation. lead screw As a result, harmonic reducers are gradually being replaced by this sort of RV reducer in sophisticated robot transmissions.

Harmonic Reducer

Three fundamental parts make up the harmonic reducer: a wave generator, a flexible gear, and a rigid gear.

The flexible gear produces regulated elastic deformation, and a wave generator called the harmonic drive reducer causes it to mesh with the stiff gear to convey motion and power. The working principles, transmission modes, and application industries of planetary, RV, and harmonic reducers are different from each other.

Small volume, light weight, big bearing capacity, lead screw high motion precision, and single-stage transmission ratio are characteristics of harmonic reducers for small robots. The key harmonic gear is flexible and requires repetitive high-speed deformation, making it more fragile and having a limited bearing capacity and life.

Both have fewer tooth difference meshing. RV typically uses a cycloid needle wheel; harmonic tooth shapes were used before involute tooth shapes; currently, some manufacturers utilize double arc tooth shapes, lead screw which are significantly more sophisticated than involute tooth shapes.


There is a complimentary relationship between different reducer kinds; they cannot replace one another.

The two types of drives, RV and harmonics, work well together, but it is possible that local rivalry will emerge in the market for medium- and low-load applications

advances in structural design optimization and manufacturing processes.

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