What is a gear motor? What are geared motors used?

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What is a gear motor?

Gear motor is one of the most popular micro motor applied on markets. In the 21st century, the rapid development of global industrialization and the popularization of smart homes have driven the rapid expansion of the market for gear motors. Based on the reports from technavio (DC Motors Market by Type and Geography – Forecast and Analysis 2021-2025)

DC Motor Market Analysis

,and the DC motor market is expanding with a fast and steady growth. However, in many industrial fields, what engineers want is a low-speed, high-torque micro-transmission solution which most of electrical motors cannot achieve. That is why engineers designed different gearboxes with electrical motors. Gearbox can reduce the speed and increase the torque of motors. The combination of the gearboxes and the motors is called —— geared motor.

Types and advantages of different geared motors

According to the structural design of the gearbox, there are 3 types of geared motors. These types of gearbox has its own advantages and disadvantages. So engineers can choose the appropriate gearbox according to their needs.

Spur gear motor

The design concept of the spur gear reducer is to reduce the speed of the transmission through the gear ratio generated by the meshing of gears with different numbers of teeth. So the gears of each stage are the points of force, and the speed of the transmission decreases step by step from the motor shaft, and the torque increases step by step. This is the most primitive gearbox design.

Spur gear motor

Planetary gear motor

The planetary gearbox is mainly composed of planetary gear, sun gear and outer ring gear. And the design of different reduction ratios is realized by controlling the number of teeths of the solar energy and the number of teeths of the planetary gear. For planetary gearbox, the first-stage reduction ratio of the standard planetary gearbox is suggested les than 1:10. According to the experimental results, it is shown when the reduction ratio of each stage of the gearbox is 1:4 or 1:5, the efficiency of the reduction box will bethe highest. So engineers can achieve higher reduction ratio requirements by designing a 2-stage 3-stage reduction structure. But it means the length of the gearbox will increase compare with low gear ratio gearbox.

Planetary gearbox

Harmonic gear motor

Clarence Walton Musser developped the basic model on Harmonic gear system in 1957. And based on his thoery, the main accessories of the harmonic reducer are Circular spline, Flex spline and wave generator. Therefore harmonic gearbox mainly drives the wave generator to generate motion waves through the rotation of the input shaft. The moving wave drives the Flex spline and the Circle spline. Then the deceleration effect is achieve through the different gear ratios of the flex spline and the circle spline.

What is the advantages and disadvantages between Spur gearbox vs Planetary gearbox vs Harmonic gearbox?

Characteristic/Gears TypesSpur Gear MotorPlanetary Gear motorHarmonic Gear motor
Motor TypeDC motorDC motor/Stepper MotorStepper Motor/Servo Motor
PriceCheapHighVery High
EfficiencyLowHighVery High
Precision/backlashLowHighVery High
SizeBased on requirements(Circle or Sqaure)SmallSmall
Torque capacityLowMediumHigh
NoiseMediumSmallVery Small


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