Reducers are mechanical transmissions widely used in shipbuilding, water conservancy, power, engineering machinery, petrochemical, and other industries. There are many types of reducers. You need to understand the advantages and disadvantages of them before choosing the right one that suits your application. Then let’s explain the advantages and disadvantages of various reducers:
The worm gear reducer has an input worm and an output gear. It’s characterized by high transmission torque, a high reduction ratio, and a wide range, namely a reduction ratio of 5 to 100 for a single-stage drive. But its transmission mechanism is not coaxial input and output, which limits its application. And its transmission efficiency is quite low – no more than 60%. As it’s a relative sliding friction transmission, the torsional rigidity of the worm gear reducer is slightly lower, and its transmission components are easy to wear with a short service life. Moreover, the reducer easily generates heat, so the allowable input speed is not high (2,000 rpm). These limit its application.
Use servo motors to increase torque: With the development of servo motor technologies from high-torque density to high-power density, the speed can be increased to 3000 rpm. As speed is increased, the power density of the servo motor is greatly improved. This indicates that whether the servo motor shall be equipped with a reducer or not depends on application needs and costs. For example, it’s useful for applications that require moving the load or precise positioning. Generally, it can be used in aviation, satellites, medical industry, military technologies, wafer equipment, robots, and other automated equipment. In all these scenarios, the torque required to move the load always far exceeds the torque capacity of the servo motor itself. And this issue can be effectively handled by increasing the output torque of the servo motor through a reducer.
It’s able to increase the output torque by directly increasing the output torque of the servo motor. But it requires not only expensive magnetic materials but also a more robust motor structure. The torque increase is proportional to the control current increase. Then the increasing current will require a relatively larger driver, more powerful electronic components, and electromechanical equipment, which will increase the control system cost.
Another way to increase the output torque is to increase the power of the servo motor. By doubling the servo motor speed, the servo system’s power density can be doubled as well, without changing the driver or control system components and without extra cost. Here, it requires reducers to achieve “decelerating and torque increasing”. Therefore, reducers are a must for high-power servo motors.
The harmonic gear reducer is composed of a rigid internal gear ring, a flexible external gear ring, and a harmonic generator. It uses the harmonic generator as the input component, the rigid internal gear ring as the fixed component, and the flexible external gear ring as the output component. Among them, the flexible external gear ring is made of a special material with thin inner and outer walls. This is the core technology of this type of reducer. Presently, there is no manufacturer in Taiwan, China, that can produce harmonic gear reducers. The series of planetary reducers with small tooth number differences has mechanical output characteristics between harmonic gears and cycloid pin gear speed reducers. It can achieve zero backlash and is a market product most comparable to harmonic gear reducers.
Harmonic reducers have high transmission precision and low transmission backlash. They are equipped with a high and wide reduction ratio of 50 to 500 for a single-stage drive. In addition, its transmission efficiency is higher than that of the worm gear reducer. As the reduction ratio changes, the efficiency of the single-stage drive can vary between 65 and 80%. But due to its flexible transmission, its torsional rigidity is low. The service life of the flexible external gear ring is short, and the reducer easily generates heat. As a result, its allowable input speed is not high – only 2,000 rpm. These are its disadvantages.
Post time: May-06-2023