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In the field of micro DC geared motors, the cylindrical structure has become the core power source for smart home devices, automation equipment, DIY robots, and small transmission mechanisms, thanks to its compact size, easy installation, and stable torque output. Among them, the three models 60GA775, 37GB555, and 37GB520 are the most commonly used and easily confused popular models—they have similar appearances and are all brush DC geared designs, but there are significant differences in power, torque, and volume. Choosing the right one can improve equipment stability, while choosing the wrong one can lead to insufficient power, shortened service life, or even failure of the equipment to operate normally.
This selection guide will help you quickly distinguish the differences between the three motors from four dimensions: model interpretation, core parameter comparison, scenario adaptation, and selection skills, so as to accurately match your usage needs. Whether you are an engineering selector, a cross-border e-commerce seller, or a DIY enthusiast, you can understand and choose correctly at a glance.
I. First Understand the Model: 3 Letters + Numbers, Hiding the Core Information of the Motor
Many people only look at the model numbers when selecting, but ignore the meaning behind the letters and numbers. In fact, as long as you understand the model, you can quickly judge the core specifications of the motor and avoid blind selection. The three motors follow the same naming logic, which is clear at a glance when disassembled:
General Naming Rule: Outer Diameter (mm) + Gearbox Mark + Motor Body Model
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60GA775: 60 = Gearbox outer diameter is about 60mm; GA = Cylindrical parallel shaft gearbox; 775 = Motor body is RS-775 brushed DC motor (high-power core);
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37GB555: 37 = Gearbox outer diameter is about 37mm; GB = Cylindrical parallel shaft gearbox; 555 = Motor body is RS-555 brushed DC motor (medium-power core);
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37GB520: 37 = Gearbox outer diameter is about 37mm; GB = Cylindrical parallel shaft gearbox; 520 = Motor body is RS-520 brushed DC motor (low-power core).
Key Summary: 60GA775 is the largest in size and the most powerful among the three; 37GB555 and 37GB520 have the same size, but the 555 motor core has higher power and torque than 520, which is a "same size, different performance" combination.
II. Core Parameter Comparison: A Table to Distinguish the Differences Between the Three Motors
The core of selection is matching parameters. The following is a comparison of the typical specifications of the three motors (all based on the commonly used 12V/24V voltage; parameters will vary with different reduction ratios, for selection reference only). Focus on the three core indicators: size, power, and torque, which determine whether the motor can adapt to the equipment.
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Parameter Type
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60GA775
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37GB555
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37GB520
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Key Selection Tips
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Gearbox Outer Diameter
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60mm
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37mm
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37mm
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The 60mm size is larger, requiring sufficient installation space; 37mm is suitable for small equipment
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Motor Body
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RS-775 (High Power)
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RS-555 (Medium Power)
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RS-520 (Low Power)
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The motor body determines the power upper limit: 775 > 555 > 520
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Rated Power
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35-80W
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10-30W
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5-15W
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The higher the power, the stronger the ability to drive the load, and the higher the energy consumption
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Rated Torque
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5-80kgf·cm
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0.5-35kgf·cm
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0.3-15kgf·cm
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Torque determines "strength"; choose high torque for heavy loads and low torque for light loads
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Speed Range (After Deceleration)
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10-1000RPM
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10-1500RPM
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10-2000RPM
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Speed is related to the reduction ratio; the larger the reduction ratio, the lower the speed and the higher the torque
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Output Shaft Type
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D-type Shaft (8mm)
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D-type Shaft (6mm)
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D-type Shaft (6mm)
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Shaft diameter determines the adapter specification of coupling/gear; 8mm is suitable for heavy loads, 6mm for light loads
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Weight
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350-500g
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300-350g
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250-300g
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Weight is positively correlated with power; 37GB520 is preferred for lightweight equipment
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Applicable Voltage
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12V/24V (Mainstream)
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6V/12V/24V (Mainstream)
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6V/12V (Mainstream)
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It is necessary to match the equipment power supply system to avoid motor damage caused by voltage mismatch
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Supplementary Note: All three motors are equipped with metal gearboxes (zinc alloy/steel material), supporting forward and reverse rotation and PWM speed regulation, and are compatible with controllers such as Arduino and Raspberry Pi. The core differences lie in the trade-off between "power-torque-volume", and these three dimensions should be prioritized during selection.
III. Scenario-based Selection: Which Motor is Suitable for Your Equipment?
The core principle of selection is "on-demand matching"—there is no need to pursue the highest power, nor to choose a model with insufficient power to save costs. Only by combining specific application scenarios can we achieve both "cost-effectiveness and stability". The following are the typical adaptation scenarios of the three motors; you can quickly select by referring to them.
1. 60GA775: First Choice for Heavy Load and High Power Scenarios
As the most powerful model among the three in terms of power and torque, 60GA775, with its high load capacity, is suitable for heavy-load scenarios requiring "high torque and low speed", especially for equipment that operates continuously for a long time with large load fluctuations.
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Typical Applications: Small industrial conveyors, large robot chassis, heavy-duty automatic doors, small lifting platforms, medical equipment (such as small hospital bed lifting), high-power DIY robotic arms;
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Selection Tips: The equipment needs to reserve more than 60mm of installation space, and the power supply system needs to match 12V/24V. It is suitable for scenarios with high power requirements and no sensitivity to size and energy consumption. At the same time, note that its high power will generate a certain amount of heat during operation, so it is recommended to do a good job in heat dissipation design.
2. 37GB555: First Choice for Medium Load and General Scenarios
37GB555 is the "most cost-effective" model among the three. With a compact size (37mm outer diameter), moderate power and torque, it balances power and convenience, and is suitable for most medium-load scenarios. It is also one of the best-selling models on the market.
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Typical Applications: Smart door locks, express cabinet locks, automatic curtains, vending machines, medium-sized DIY robots, pan-tilt heads, cash counters, small robotic arms;
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Selection Tips: Suitable for equipment with size requirements and certain power support, such as smart home equipment (automatic curtains) and small automation equipment (vending machine valves). It can not only meet the power demand but also not take up too much space, making it the first choice for "general-purpose" use.
3. 37GB520: First Choice for Light Load and Miniaturization Scenarios
37GB520 has the same size as 37GB555, but with smaller power and torque. It focuses on "lightweight and low energy consumption", and is suitable for small equipment with small loads and low power requirements, especially for DIY and small electronic products.
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Typical Applications: Small DIY cars, toy models, micro pan-tilt heads, small fans, smart wearable devices (small drives), light-load valves, educational experimental equipment;
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Selection Tips: Suitable for lightweight and low-energy-consumption scenarios, such as small robots made by DIY enthusiasts and micro motors for educational experiments. It has low cost and easy installation, but is not suitable for driving heavy loads, otherwise, it will cause insufficient power, motor overheating, and shortened service life.
IV. Selection Pitfall Avoidance Skills: 4 Key Points to Avoid Mistakes
Many people easily fall into the misunderstanding of "the higher the power, the better" or "the smaller the size, the better" when selecting, leading to mismatch between the motor and the equipment. Here are 4 core skills to help you avoid selection pitfalls and improve equipment stability.
Skill 1: Calculate the Load First, Then Select the Torque (The Core of the Core)
The first step in selection is to calculate the actual load demand of the equipment. It is recommended to reserve a 20%-30% torque margin to cope with instantaneous load fluctuations and avoid motor damage due to overload—this is the core logic of motor selection and the most easily overlooked step. According to engineering practice experience, the output torque of the DC geared motor should meet: Output torque ≥ Maximum torque required by the load × 1.2 (safety factor). At the same time, it should be calculated in combination with the reduction ratio. The larger the reduction ratio, the higher the output torque and the lower the speed. The reduction ratio should be accurately matched according to the required speed of the equipment.
Example: If the equipment requires 5kgf·cm of torque, 37GB555 (rated torque 0.5-35kgf·cm) is preferred to reserve sufficient margin; if 40kgf·cm of torque is required, 60GA775 must be selected, and the 37GB series cannot meet the demand.
Skill 2: Match the Installation Space to Avoid "Inability to Install"
The 60mm outer diameter of 60GA775 is much larger than that of the 37GB series. If the internal space of the equipment is narrow (such as small smart door locks and micro toys), forcing the installation of 60GA775 will lead to inability to assemble; on the contrary, if the equipment space is sufficient but the 37GB series is selected, insufficient power may occur. It is recommended to measure the installation space of the equipment first, then select the model according to the load demand.
Skill 3: Voltage Matching to Avoid Motor Damage
The three motors have different applicable voltages: 37GB520 is mainly suitable for 6V/12V, and 60GA775 is mainly suitable for 12V/24V. Connecting a 12V motor to a 24V power supply will cause the motor to rotate too fast, overheat and burn out; connecting a 24V motor to a 12V power supply will cause insufficient power and failure to start. At the same time, it is necessary to select according to the equipment power supply system. For example, mobile equipment needs to pay attention to power consumption and select energy-efficient models to extend battery life.
Skill 4: Do Not Blindly Pursue High Power, Balance Energy Consumption and Service Life
The higher the power, the higher the energy consumption, and the more heat the motor generates during operation. During long-term continuous operation, excessive power will shorten the motor life. For example, a small DIY car can be satisfied with 37GB520. If 60GA775 is selected, it will not only waste cost but also increase energy consumption, leading to shortened car battery life. In addition, the service life of a brushed DC motor is closely related to load and speed. Reasonably matching power and load can effectively extend the motor service life (usually up to 1000-3000 hours).
V. Summary: Quick Selection Rhyme, Easy to Understand
Finally, we have sorted out a simple and easy-to-remember selection rhyme for you. Combined with the above content, you can easily select the three motors:
"For heavy load and high power, 60GA775 is the first choice; for medium load and general use, 37GB555 is the most cost-effective; for light load and miniaturization, 37GB520 is excellent; torque depends on load, space depends on outer diameter, voltage must match, and margin must be reserved"
In fact, there is no absolute "good or bad" among 60GA775, 37GB555, and 37GB520, only "whether it is suitable". As long as you clarify the three core needs of the equipment: load, installation space, and power supply voltage, and combine parameter comparison and scenario adaptation, you can easily avoid selection pitfalls and make the motor the "stable power core" of the equipment.
If your equipment scenario is relatively special, or you are not sure which model to choose, welcome to leave a comment below, tell us your equipment type, load demand and installation space, and we will help you accurately recommend the appropriate model and reduction ratio~