Planetary Gearbox: Characteristics, Applications, and Classification

The main transmission structure of (planetary reducers) includes planetary gears, sun gears and external gear rings.

Due to its unique structure, the minimum reduction ratio of a single-stage planetary reducer is typically 3, and the maximum is generally not more than 10. Common reduction ratios include 3, 4, 5, 6, 8, 10, etc. The number of stages of the reducer is generally not more than 3, but some custom reducers designed to meet the demand for large reduction ratios may have 4 stages of reduction.

Compared with other types of reducers, planetary reducers have many significant advantages. It has high rigidity, high precision (single-stage accuracy can reach within 1 minute), high transmission efficiency (single-stage efficiency is usually 97% – 98%), high torque/volume ratio, and can achieve lifelong maintenance-free.

It is precisely because of these outstanding features that planetary reducers are often installed on stepper motors and servo motors to reduce speed, increase torque and match inertia.

The rated input speed of planetary reducers is relatively high, which can reach more than 18,000 rpm (this is related to the size of the reducer itself. The larger the reducer, the relatively smaller the rated input speed). In industrial applications, the output torque of planetary reducers is generally not more than 2000 Nm, but specially designed super-large torque planetary reducers can reach more than 10,000 Nm. Its working temperature is usually between -25°C and 100°C, and the working temperature range can be changed by adjusting the type of grease.

Next, let’s understand a few key concepts about planetary reducers:

Number of stages: Refers to the number of sets of planetary gears. When one set of planetary gears cannot achieve a large transmission ratio, 2 or even 3 sets may be required to meet the demand. With the increase in the number of planetary gears, the length of 2-stage or 3-stage reducers will increase accordingly, while the efficiency will decrease.

Backlash: Fix the output end and rotate the input end clockwise and counterclockwise. When the input end generates ±2% of the rated torque, the small angular displacement at the input end of the reducer is the backlash, and the unit is “minute”, which is one sixtieth of a degree, also known as the backlash.

Planetary reducers are a kind of product that is extremely widely used in the industrial field. Their performance can be comparable to that of high-end reducers, but they have relatively affordable industrial-grade prices. It is widely used in many industrial occasions.

This reducer has the advantages of small size, light weight, strong load-carrying capacity, long service life, stable operation and low noise. It has the unique characteristics of power splitting and multi-tooth meshing, and the maximum input power can reach 104 kW. It is suitable for multiple industrial sectors such as hoisting and transportation, construction machinery, metallurgy, mining, petrochemical, construction machinery, light industry and textile, medical equipment, instrumentation, automobiles, ships, weapons and aerospace, including new varieties of the planetary series such as WGN fixed-axis transmission reducer, WN mother-son gear transmission reducer, elastic evenly loaded small tooth difference reducer, etc.

Planetary reducers mainly include planetary reducers and (P planetary gear reducers), etc.

Overall, with its excellent performance and wide applicability, planetary reducers play an important role in modern industry and provide a strong guarantee for the efficient and stable operation of various mechanical equipment.

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