The "power converter" in industrial transmission: What's the deal with reducers?

In automated production lines, robot joints, construction machinery and other equipment, reducers are like "power regulation masters" - converting the high-speed and low-torque of motors into low-speed and high-torque, while ensuring transmission accuracy and stability. However, there are numerous types of reducers on the market, such as planetary, worm gear, cycloidal pinwheel, and harmonic... Different types are suitable for vastly different scenarios. Choosing the right one can make tasks much easier, while choosing the wrong one may lead to frequent equipment failures. Today, we will use the most straightforward way to break down the core differences among mainstream reducers! 
I. Planetary Gear Reducer: The "Preferred Choice" for High-Precision Applications
Core Structure: Composed of a sun gear, planetary gears, an internal gear ring, and a planet carrier. Power is input through the sun gear, distributed and transmitted by multiple planetary gears, and finally output by the planet carrier. 
Outstanding advantages: Small in size but with high power density, single-stage transmission efficiency can reach 97% - 98%, the precision type can achieve extremely low backlash, and the input and output are coaxial, making the installation layout particularly convenient. 
The applicable scenarios include industrial robot joints, precision machine tools, servo motor drive equipment, medical devices, and other occasions with high requirements for precision and rigidity. For instance, the precise positioning during robot welding cannot do without the high rigidity support of planetary reducers. 
A small reminder: The complex structure leads to higher costs, and the heat dissipation requirements are higher than those of ordinary reducers. Attention should be paid to ventilation and cooling. 
II. Worm Gear Reducer: The "Safe Model" with High Reduction Ratio and Self-locking Function
Core Structure: By means of the 90-degree cross-meshing transmission between the worm (similar to a screw) and the worm gear (a special toothed gear), a single stage can achieve a high reduction ratio ranging from 10:1 to 100:1. 
Outstanding advantages: The most prominent feature is the "self-locking property" - when the lead angle of the worm is less than the friction angle, the worm can only drive the worm wheel, and reverse transmission is impossible. This is particularly suitable for lifting equipment (such as elevators and winches), as it can prevent the load from reversing and causing safety accidents. Moreover, it operates smoothly, generates very low noise, and has a compact structure. 
The applicable scenarios include: equipment for improvement, valve actuator, stage machinery, small lifting equipment, etc. These scenarios do not have high requirements for efficiency but need a large speed ratio and safety self-locking. 
A small reminder: Sliding friction leads to relatively low efficiency (40% - 90%), generates significant heat, and requires high-quality lubricating oil and heat dissipation design. It is not suitable for continuous operation at high power.
III. Parallel Shaft Gear Reducer: The "Cost-Effective Option" for General Industry
Core Structure: The input shaft and output shaft are parallel, and the reduction is achieved through the series connection of multiple stages of cylindrical gears (straight, helical, or herringbone), with a high level of technical maturity. 
Outstanding advantages: Simple and reliable structure, convenient maintenance, relatively low cost. The transmission efficiency of helical or herringbone versions can reach over 95%, and it can withstand heavy loads and shock loads. 
The applicable scenarios include general industrial equipment such as conveyor belts, mixers, fans, and water pumps, as well as heavy industrial settings like mining machinery and metallurgical equipment. For instance, in factory production lines, the drive of conveyor belts using parallel shaft gear reducers is both durable and cost-effective. 
A small reminder: The volume and weight are relatively large, and the input and output shafts are not in the same line, so more installation space needs to be reserved. 
IV. Cycloidal Pinwheel, Harmonic & RV Reducers: "Customized" Options for Special Needs
Cycloidal pinwheel reducers: With a single-stage transmission ratio ranging from 11 to 87, they feature multiple teeth engaging simultaneously, providing strong load-bearing capacity. They are suitable for compact space scenarios in industries such as chemical mixing and food machinery that require extremely high gear ratios, but their maintenance is relatively complex. 
Harmonic gear reducer: extremely compact in size and light in weight, it can achieve zero backlash transmission with extremely high precision. It is the core choice for small industrial robots and semiconductor equipment. However, the flexible gear is prone to fatigue and has a limited lifespan. 
RV reducer: A planetary + cycloidal compound structure, it combines ultra-high rigidity and high precision, making it the "ace" of heavy industrial robot joints. However, it has a complex structure and is expensive. 
Selection Tips for Reducers
High precision, small space → Planetary reducer
Self-locking required, high gear ratio → Worm gear reducer
General scenarios, cost-effective → Parallel shaft gear reducer
Robots, ultra-precision → Harmonic / RV reducer
High gear ratio, shock resistance → Cycloidal pinwheel reducer
The key to selecting the right reducer is to first clarify the equipment's speed, torque, precision requirements, and installation space, and then match the corresponding type. If you are still unsure, it is recommended to consult a professional technical team to avoid affecting the equipment's lifespan due to improper selection!