Doncen Motor focus on the development and design of micro DC gear motors for 20 years. As a pioneer in the research and development of small gear motors( Power ≤ 250W ） in China, we share how we define a gear motor or geared motors in this article.
1. What is a gear motor
A gear motor (dc geared motor) is an electric motor (dc brush motor, bldc motor , ac motor) combine with a gear drive reduction system （gearbox） The output shaft of the motor is connected to the gear, and the bearing provides support as shown below. Gear motors can provide higher torque and lower speed than electric motors.
2. Working Prnciple of DC Geared Motor
The working principle of the gear motor can be broken down into two parts.
- DC motor part – converts electrical energy into mechanical energy to drive the motor to rotate.
- Gearbox part – reduces the speed and increases the torque through the gear.
Part 1: How a DC Motor Converts Electrical Energy into Mechanical Energy
The core components of a DC motor are the stator and the rotor, and its working principle is as follows:
When powered on, the coil generates a magnetic field
- Current flows through the rotor windings (or armature), creating a magnetic field.
- This magnetic field interacts with the fixed magnetic field of the stator, producing attractive and repulsive forces.
Electromagnetic force drives rotor rotation
- Due to the action of the commutator, the direction of the current continuously changes, ensuring continuous rotation of the rotor.
- As the rotor rotates, mechanical energy is transmitted through the motor shaft.
Part 2: How the Gear System Reduces Speed and Increases Torque
DC motors generally have high speed and low torque characteristics. To meet different application requirements, a gear reduction mechanism is used.
Principle of Gear Reduction
- The gearbox consists of multiple gears, commonly planetary gears, helical gears, or worm gears.
- By using a larger gear to drive a smaller gear, the system achieves speed reduction and torque enhancement.
Torque Enhancement Mechanism
- Since torque = force × radius, using larger gears can increase output torque.
- For example, if the gear ratio is 1:10, the motor speed is reduced by 10 times, while the torque is increased by 10 times (considering efficiency losses).
3. Gear motor market analysis
Gear motors are among the most widely used micro motors across various industries. In the 21st century, the rapid advancement of global industrialization and the widespread adoption of smart home technologies have significantly driven the growth of the gear motor market. According to Technavio’s report (DC Motors Market by Type and Geography – Forecast and Analysis 2021-2025), the DC motor market is experiencing steady and rapid expansion.
However, in many industrial applications, engineers require low-speed, high-torque micro-transmission solutions—a demand that conventional electric motors alone cannot fulfill. To address this, gearboxes are integrated with electric motors to modify their performance characteristics. A gearbox reduces the motor’s speed while increasing its torque, making it suitable for precision-driven and high-load applications. The combination of a motor and gearbox is commonly referred to as a “geared motor.
4. Types and advantages of different geared motors
The classification of gear motors can be divided into:
4.1 Spur gear motor
Reduction method: adopts tower gear reduction structure (multi-stage parallel shaft gear set).
It is composed of multiple spur gears stacked vertically, and the number of teeth of each gear increases step by step, and the reduction is achieved through step-by-step meshing.
The power is transmitted to the first-stage pinion through the input shaft, and then to the larger gear step by step, and finally output to the load end.
| Pros | Cons |
|---|---|
| Simple, cost-effective | Noisy |
| Maintain high efficiency at low speed ratio | Low space utilization |
| Flexible output shaft position | low efficiency at high gear ratios |
4.2 Planetary gear motor
Reduction method: planetary reduction structure (planetary gear set) is adopted.
It consists of a central sun gear (Sun Gear), multiple planetary gears (Planet Gears), an outer ring gear (Ring Gear) and a planet carrier.
The power is input from the sun gear, the planetary gears revolve around the sun gear and rotate, and the decelerated power is output through the planet carrier.
| Pros | Cons |
|---|---|
| High torque density, handles impact loads. | Complex |
| Compact, ideal for tight spaces. | Expansive |
| High efficiency (90%~95%), bidirectional. |
4.1.3 Worm gear motor
Reduction method: Worm gear reduction structure is adopted.
It consists of a worm (screw-shaped active part) and a worm wheel (helical gear-shaped driven part), and the two axes are staggered at 90 degrees.
The helical teeth of the worm mesh with the worm wheel, and a large reduction ratio can be achieved through a single-stage transmission.
| Pros | Cons |
|---|---|
| Self Locking | Low efficiency |
| single-stage reduction ratio can reach 5:1~100:1 | One-way transmission |
| Low Noise | Easy broken |
Rated Article：What is a Worm Gear Motor
5. Application of DC Gear motor
Geared motors are often used in closed space, small size, high torque, low speed applications. The design of the geared motor is more compact, with lower noise and more energy-saving. Doncen Motor found that our customers tend to use it in the following applications.
