RV Reducer vs. Harmonic Drive Gearbox

Read more

In industrial robotics, precision reducers are crucial due to their requirements for short drive chains, compact size, high power, lightweight design, and ease of control. The most commonly used reducers in articulated robots are RV reducers and harmonic drive gearboxes.

For a deeper understanding of their operating mechanisms, we first examine the RV reducer, which is primarily employed in the high-torque joints of robot limbs, including the waist and elbow. Industrial robots with higher payloads typically utilize RV reducers across one, two, and three axes. The production process and assembly of RV reducers contribute significantly to their advantages, including higher fatigue strength, stiffness, and service life. Unlike harmonic drives, RV reducers maintain consistent motion accuracy throughout their lifespan, though they tend to be heavier and bulkier.

On the other hand, harmonic drive gearboxes are preferable for industrial robots with lighter loads or those requiring multiple axes on larger robotic structures. These gearboxes consist of components like the flexible wheel, rigid wheel, wave generator, and bearings. A notable feature of harmonic reducers is their compact size, lightweight nature, substantial bearing capacity, high precision, and significant single-stage transmission ratios. The flexible wheel, however, must undergo repeated high-speed deformations, making it somewhat fragile, thus limiting its load capacity and lifespan.

The mechanics of these reducers involve unique gear interactions, where RV reducers utilize cycloidal pinwheels, and harmonic reducers are characterized by their flexible and rigid teeth arrangements. Recently, manufacturers have started adopting advanced double arc teeth designs to enhance performance in harmonic drives.

A standard strain wave harmonic drive gearbox comprises four essential components: the flexible wheel, wave generator, rigid wheel, and bearings. In this system, the elliptical form of the wave generator facilitates the engagement and disengagement of gears with each rotation, enabling high torque transmission. In contrast, the RV reducer adopts a pin-oscillating planetary gearbox structure, introducing several advantages such as compactness, lightweight construction, a wide transmission ratio range, long service life, stability in precision, high efficiency, and smooth operation, making them widespread in applications such as machine tools, medical testing equipment, and satellite systems.

The RV reducer excels in load capacity due to its solid steel transmission components, whereas the harmonic reducer's flexible wheel limits its ability to endure significant torque and shocks, typically relegating it to lighter applications in robotic endpoints.

Considering their respective advantages, the strain wave harmonic drive gearbox is ideal for miniature, low to medium load scenarios, while the RV reducer is well-suited for medium to heavy loads, demonstrating excellent rigidity, impact resistance, smooth operation, and high precision. However, to manage large torque loads effectively, RV reducers are designed with a somewhat complicated structural setup, which increases manufacturing complexity and costs. One of the common weaknesses of the RV reducer lies in its bearings, which can easily exceed their stress limits, leading to wear or failure, particularly at higher speeds—resulting in a significant decrease in its rated torque at elevated input speeds.

The RV reducer is characterized as a high-precision control reducer, distinguished by its cycloidal pinwheel structure. With multiple gears engaging simultaneously, it offers the desirable traits of compact size, lightweight, robust rigidity, and overload resistance. The minimal backlash allows for reduced rotary vibration and inertia, resulting in superior acceleration characteristics and smooth operational performance.

For further details regarding rv reducer, feel free to contact us. Our dedicated sales team is ready to assist you in finding the best solutions tailored to your specific needs.