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Pololu 2823 - 30:1 Metal Gearmotor 37Dx68L mm with 64 CPR Encoder

This gearmotor is a powerful 12V brushed DC motor with a 30:1 metal gearbox and an integrated quadrature encoder that provides a resolution of 64 counts per revolution of the motor shaft, which corresponds to 1920 counts per revolution of the gearbox’s output shaft. These units have a 0.61"-long, 6 mm-diameter D-shaped output shaft. This gearmotor is also available without an encoder.

More details

ID: 561013

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Data sheet

DC motor powerOther
Gear materialMetal
Gear ratio30:1
Rotation speed350RPM
Shaft shapeD
Power supply voltage12V

More info


This powerful brushed DC gearmotor is available in six different gear ratios and features an integrated quadrature encoder with 64 counts per revolution (CPR) of the motor shaft. The motor and encoder portion is available by itself (no gearbox), and versions without the encoder are also available.

Gear RatioNo-Load
@ 12 V
Stall Torque
@ 12 V
Stall Current
@ 12 V

With Encoder

Without Encoder
1:111,000 RPM5 oz-in5 Amotor without gearbox
19:1500 RPM84 oz-in5 A37Dx68L mm37Dx52L mm
30:1350 RPM110 oz-in5 A37Dx68L mm37Dx52L mm
50:1200 RPM170 oz-in5 A37Dx70L mm37Dx54L mm
70:1150 RPM200 oz-in5 A37Dx70L mm37Dx54L mm
100:1100 RPM220 oz-in5 A37Dx73L mm37Dx57L mm
131:180 RPM250 oz-in5 A37Dx73L mm37Dx57L mm

Note: Stalling or overloading gearmotors can greatly decrease their lifetimes and even result in immediate damage. Stalls can also result in rapid (potentially on the order of seconds) thermal damage to the motor windings and brushes; a general recommendation for brushed DC motor operation is 25% or less of the stall current.

These motors are intended for use at 12 V, though in general, these kinds of motors can run at voltages above and below the nominal voltage (they can begin rotating at voltages as low as 1 V). Lower voltages might not be practical, and higher voltages could start negatively affecting the life of the motor.

These gearmotors are functionally identical to the previous versions we carried without end caps (they use the same motor, encoder, and gearboxes). The black plastic end cap is easily removable if you need to access the encoder or want to slightly reduce the overall gearmotor size, but there is a little bit of base plastic that will remain, as shown in the pictures below:


Warning: Do not screw too far into the mounting holes as the screws can hit the gears. We recommend screwing no further than 3mm (1/8") into the screw hole.

Using the Encoder:

A two-channel Hall effect encoder is used to sense the rotation of a magnetic disk on a rear protrusion of the motor shaft. The quadrature encoder provides a resolution of 64 counts per revolution of the motor shaft when counting both edges of both channels. To compute the counts per revolution of the gearbox output, multiply the gear ratio by 64. The motor/encoder has six color-coded, 11″ (28 cm) leads terminated by a 1×6 female header with a 0.1″ pitch, as shown in the main product picture. This header works with standard 0.1″ male headers and our male jumper and precrimped wires. If this header is not convenient for your application, you can pull the crimped wires out of the header or cut the header off. The following table describes the wire functions:

Redmotor power (connects to one motor terminal)
Blackmotor power (connects to the other motor terminal)
Greenencoder GND
Blueencoder Vcc (3.5 – 20 V)
Yellowencoder A output
Whiteencoder B output

The Hall sensor requires an input voltage, Vcc, between 3.5 and 20 V and draws a maximum of 10 mA. The A and B outputs are square waves from 0 V to Vcc approximately 90° out of phase. The frequency of the transitions tells you the speed of the motor, and the order of the transitions tells you the direction. The following oscilloscope capture shows the A and B (yellow and white) encoder outputs using a motor voltage of 12 V and a Hall sensor Vcc of 5 V:

By counting both the rising and falling edges of both the A and B outputs, it is possible to get 64 counts per revolution of the motor shaft. Using just a single edge of one channel results in 16 counts per revolution of the motor shaft, so the frequency of the A output in the above oscilloscope capture is 16 times the motor rotation frequency.


Size:37D x 68L mm1
Weight:215 g
Shaft diameter:6 mm

General specifications:

Gear ratio:30:1
Free-run speed @ 12V:350 rpm
Free-run current @ 12V:300 mA
Stall current @ 12V:5000 mA
Stall torque @ 12V:110 oz·in
Free-run speed @ 6V:175 rpm2
Free-run current @ 6V:250 mA2
Stall current @ 6V:2500 mA2
Stall torque @ 6V:55 oz·in2
Lead length:11 in


1 Length measurement does not include gearbox shaft or the raised area immediately around it.
2 This motor will run at 6 V but is intended for operation at 12 V.