25D metal gearmotor pololu

25D metal gearmotor pololu

25D metal gearmotor pololu
Pololu Robotics & Electronics | A-000000-03582
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Range of 25 mm diameter cylindrical DC motors with a 4 mm diameter D-axis. You can choose your model according to criteria suchas power, reduction ratio and the presence or not of an encoder.

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25D mm gearmotor are available according to these criteria :

  • 5 motor types : 6V HP (high power) or LP (low power) ; and 12V HP (high power), MP (medium power) or LP (low power)
  • reduction ratio (note that not all ratios ara available for all engines types)
  • the presence or not of an encoder

The dimensions, except the total length, are identical, which allows you to easily exchange one reference with another in your assembly. If you have not yet determined the shape of your future robot, do not hesitate to consult our selection of robotic chassis.

You will find below a table allowing you to identify more easily the motor most adapted to your project, according to your constraints.

Comparative table between motor with and without encoder

Encoder operation (optional) :

The Pololu DC motor encoder measures the rotation of a magnetic disc located behind the motor axis. This Hall effect encoder offers a resolution of 48 steps per revolution of the motor axis. To know the resolution per revolution of the output axis, simply multiply the reduction ratio by 48. For example, for a 34:1 ratio, the resolution is 48 x 34 = 1632 steps per revolution of the output axis.

The encoder requires an input voltage between 3,5V and 20V and consumes a maximum of 10 mA. Both outputs A and B return a square signal between 0 and the input voltage with a phase shift of approximately 90° (see oscilloscope image below). Each rising and falling edge of the two encoders indicates a step of revolution. The frequency of the edges indicates the rotation speed (1633 steps per turn of the output axis, with a 34:1 ratio) and the order of the transition indicates the direction.


The table below describes the role of the different wires to control the motor and to recover the encoder outputs.

Table describing the different wires                  Picture of the different wires

Dimensions :

  • motor diameter: 25 mm
  • motor length: from 60 to 70 mm depending on the ratio (see diagram below) - 43 mm for the 1:1 ratio
  • axis diameter : 4 mm (D-shape)
  • shaft length: 12.5 mm (including a 2.5 mm metal ring)
  • weight: 95 g (60 g for 1:1 ratio)

The motor comes with a black plastic end cap (which can be removed).

Diagram that shows the dimensions of the 25D mm line of gearmotors

Specificity of the 1:1 version:

The 1:1 ratio motor still has an encoder, but is supplied without a reduction box. It does not have an output shaft, but a 12-tooth gear, compatible with the reduction blocks of all other versions. As such, this engine is designed more to serve as a replacement than to be used directly.

Note: In order to preserve the motor and ensure optimum longevity, it is recommended not to subject it to a voltage or load exceeding its rated characteristics.

We also invite you to browse the other Pololu motor gearbox ranges:

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