Working principle and common fault diagnosis of reducer

Writer：tilireducer Time：2026-07-30 16:08:04 Browse：8℃

Reduction gears are generally used in transmission equipment with low rotational speed and high torque. They achieve the purpose of speed reduction by meshing a gear with fewer teeth on the input shaft of the reducer with a larger gear on the output shaft. Ordinary reduction gears also have several pairs of gears with the same principle to achieve the desired speed reduction effect. The ratio of the number of teeth between the large and small gears is the transmission ratio. When it comes to the issues of insufficient accuracy and short lifespan of domestic robots, everyone may blame our domestic reduction gears. Some say our domestic reduction gears are not accurate enough and have a short lifespan. In short, a host of problems have emerged.Dynamic Demonstration of Reduction Gear PrincipleWhy is it that the reduction gears used in domestic robots are exactly the same as those from the four major families, but the installed effect is worse than that of the four major families? In fact, the problem does not only come from the reduction gears. For example, problems may occur in assembly and systems. Today, let me teach you how to distinguish the quality of reduction gears.Dynamic Demonstration of Reduction Gear PrincipleAnalysis of Reduction Gear Principle01RV Reduction GearThe RV reduction gear is one of the more common types of worm gear reducers in the family. It consists of a worm and a worm wheel, and is a transmission mechanism with compact structure, large transmission ratio, and self-locking function under certain conditions. It is one of the most commonly used reduction gears, and it has low vibration, low noise, and low energy consumption.

Working Principle: RV reducers are generally used in low-speed, high-torque transmission equipment. They achieve the purpose of speed reduction by meshing a gear with fewer teeth on the input shaft of the reducer with a larger gear on the output shaft. Ordinary reducers also have several pairs of gears with the same principle to achieve the desired speed reduction effect. The ratio of the number of teeth between the large and small gears is the transmission ratio. A reducer is a power transmission mechanism that uses a gear speed converter to reduce the rotational speed of a motor to the desired rotational speed and obtain a larger torque. RV Reducer Principle Dynamic Demonstration It is generally believed that the three giants of RV in the robotics industry are Teijin, Sumitomo, and SPINEA. The emphasis on the robotics industry is because some reducers are also very powerful, but they are not widely used in the robotics industry. For example, Chai Aifu, whose reducers have high performance and precision, are mainly used in high-end machine tools, and there are not many in the industrial robotics industry. 02 Harmonic Reducer It is used for industrial robots with small loads or for the end axes of large robots. The harmonic reducer is a type of harmonic transmission device, which includes a harmonic accelerator and a harmonic reducer. The harmonic reducer mainly consists of a rigid wheel, a flexible wheel, a bearing, and a wave generator, all of which are indispensable. Among them, the number of teeth on the rigid wheel is slightly larger than that on the flexible wheel. The characteristics of harmonic reducers for small robots are small size, light weight, high load capacity, high motion accuracy, and a large single-stage transmission ratio.

Working Principle: The harmonic gear reducer is composed of a fixed inner rigid gear, a flexible gear, and a wave generator that causes radial deformation of the flexible gear. Harmonic gear reducers are a new type of transmission structure in gear reducers. They utilize the controlled elastic deformation waves generated by the flexible gear to cause relative tooth misalignment between the rigid gear and the flexible gear, thereby transmitting power and motion. This transmission differs fundamentally from general gear transmission and exhibits particularities in meshing theory, set calculation, and structural design. Harmonic gear reducers have advantages such as high precision and high load capacity. Compared to conventional reducers, they use 50% less material, resulting in a reduction of at least one-third in volume and weight.Dynamic Demonstration of Harmonic Gear Reducer Principle5 Steps to Quickly Identify the Quality of Reducers01 Transmission Efficiency: Reduced Output PowerTransmission efficiency is one of the important evaluation indicators for reducers. Testing transmission efficiency requires specialized equipment, making it difficult for customers to measure specific data themselves. However, it is possible to make horizontal comparisons. Heat generation is the most intuitive comparison method. We have learned from physics that energy is conserved, and greater heat dissipation indicates that more power from the motor is being used to eliminate friction, resulting in reduced output power. Reduced output power naturally leads to weaker load capacity, which can result in a lack of force, smaller acceleration, and slower timing.02 Lifespan: Time Determines QualityThe lifespan of a reducer mainly depends on the lifespan of its bearings. Generally speaking, bearings are the first to fail, especially in harmonic gear reducers. For RV reducers, the planetary structure is also a point prone to damage. Early wear and tear usually occurs within a few months to a year, depending on operating conditions. Therefore, reducer manufacturers that ship large quantities of products as robot demand increases should be cautious.03 Heat Generation: Precision or HeatThe precision of a reducer depends on the degree of gear meshing. If the meshing clearance is too large, the precision of the reducer will be poorer. Using a slight interference fit can improve precision, but it can also lead to excessive heat generation. In RV reducers, the heat generation difference in Teijin structures is not so obvious, but for the same type of harmonic gear reducers, the degree of heat generation varies greatly among different brands. Not to mention, HD is the only manufacturer in the harmonic gear industry that can achieve both high precision and low heat generation.04 Precision: An Important Indicator for Evaluating ReducersThis includes two types: angular transmission precision, which is marked in the reducer manual and affects the absolute positioning precision of the robot; Another aspect is the repeatability positioning accuracy, which is not mentioned in the reducer manual. This affects the repeatability positioning accuracy of the robot. Generally, reducer manufacturers have professional equipment for measuring angular transmission accuracy, but customers can also devise some simple methods to test it. The same goes for repeatability positioning accuracy. 　　05 Oil leakage: How to distinguish between real and fake oil leakage?Regardless of the type of reducer, this is a problem that must be faced. The causes of oil leakage are relatively complex, involving oil seal brand, oil seal assembly, shaft processing technology, usage method, and so on. Moreover, oil leakage is also divided into real and fake oil leakage. So-called fake oil leakage refers to oil leakage that occurs shortly after operation, with a small amount of leakage, and it disappears after a short period of time. This is generally due to internal pressure release, and once the pressure is released, it is fine. However, the occurrence time of real oil leakage is uncertain. It may leak from the beginning, in which case it is likely due to product quality or assembly quality issues; or it may occur after a long period of operation, which is generally due to the lifespan of the oil seal. Improper use is excluded.Troubleshooting methods for reducer faults01 "O" ring curseIn addition to the oil seal problem of the reducer itself, the design and assembly of reducer components by robot manufacturers can also have an impact, because the sealing of the reducer, besides the oil seal, also includes the O-ring.

O-rings are a common standard component in product sealing design, and there are corresponding national standards to refer to. In robot reducers, most manufacturers will already assemble the O-rings and machine the O-ring grooves. In some cases, the manufacturer does not provide O-rings, and there are no O-ring grooves on the reducer. In this case, it is necessary to design them on the mounting flange. However, due to the capillary phenomenon, base oil will still penetrate. 02 Assembly Design and Assembly ProcessWhy do many domestic manufacturers wonder why their robots, using the same HD or Teijin reducers, break down earlier than the four major families? This may be due to immature assembly processes. The structure can be visually disassembled and imitated, but the assembly design and process are not visible to the robot, and even not visible in the drawings. Mature robot manufacturers have professional process engineers who specialize in robot assembly, including reducer assembly.03 Servo ControlServo control has a significant impact on the reducer. Here, servo control includes the entire system of motor, driver, and controller. Poor servo performance or poorly tuned servo can cause the motor to shake easily under different speeds or loads. If the mechanical design is not good, resonance is also common. In servo selection, domestic robots do not place much emphasis on it. Domestic robots emphasize cost-effectiveness, but in practical operations, many become more focused on price rather than performance.04 OveruseIs it a misconception that robots can work tirelessly? Firstly, robots need to rest. It is generally recommended that robots rest for one hour every 12 hours of work, of course, this is for relatively poor working environments. If the robot itself works comfortably, it is not impossible to run 24 hours a day. Secondly, robots need maintenance. Robots are also precision equipment that requires regular maintenance to reduce wear and tear and extend their service life, just like cars.05 Overload Use and ImpactThis situation is relatively common in China. Each robot model has a designated design load and inertia. It is important to note that load and inertia are two elements. Many customers only look at the load and not the inertia, so sometimes the load is not exceeded, but the inertia is exceeded by a lot, and the robot will have various problems.

Another issue is the impact problem, which is the most troublesome. There are two types of impacts: collision and sudden stop, including pressing the emergency stop button or sudden power failure. Impacts are relatively less harmful to RV, as RV has much better rigidity. Of course, the number of impacts cannot be too high, but harmonics are very sensitive to impacts. Collisions usually occur during debugging or as accidents in production. Overall, these are accidents, not intentional, but sudden stops are often due to subjective and non-standard operations.