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Pololu item #:
3257
Brand:
Pololu
Status:
Active and Preferred
This gearmotor consists of a low-power, 12 V brushed DC motor combined with a 226.76:1 metal spur gearbox. The gearmotor is cylindrical, with a diameter just under 25 mm, and the D-shaped output shaft is 4 mm in diameter and extends 12.5 mm from the face plate of the gearbox. This gearmotor is also available with an integrated encoder.
Key specifications:
| voltage | no-load performance | stall extrapolation |
|---|---|---|
| 12 V | 25 RPM, 50 mA | 16 kg⋅cm (220 oz⋅in), 0.9 A |
Alternatives available with variations in these parameter(s): gear ratio motor type encoders? Select variant…
Compare all products in 12V Low-Power (LP) 25D mm Gearmotors.
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25D mm metal gearmotor. |
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Pololu 25D mm gearmotor with bracket. |
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Pololu 60×8mm wheel on a Pololu 25D mm metal gearmotor. |
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12mm Hex Wheel Adapter for 4mm Shaft on a 20D mm Metal Gearmotor. |
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Dagu Wild Thumper wheel 120×60mm (chrome) with Pololu 25D mm metal gearmotor. |
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Partially disassembled Dagu Wild Thumper 6WD chassis with one of the gearmotors visible. |
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Encoder A and B outputs for 25D mm HP 6V metal gearmotor with 48 CPR encoder (motor running at 6 V). |
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Encoder A and B outputs for 25D mm LP 6V metal gearmotor with 48 CPR encoder (motor running at 6 V). |
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Dimensions of the Pololu 25D mm metal gearmotors without encoders. Units are mm over [inches]. |
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An assortment of Pololu metal gearmotors. |
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These cylindrical brushed DC gearmotors are available in a wide range of gear ratios and with five different motors (two power levels of 6 V motors and three power levels of 12 V motors). The gearmotors all have the same 25 mm diameter case and 4 mm diameter gearbox output shaft, so it is generally easy to swap one version for another if your design requirements change (though the length of the gearbox tends to increase with the gear ratio). Each version is also optionally available with an integrated 48 CPR quadrature encoder. See the 25D metal gearmotor datasheet (2MB pdf) for more information, including detailed performance graphs for each gearmotor version. You can also use our dynamically sortable 25D gearmotor comparison table to search for the version that offers the best combination of speed, torque, and current draw for your particular application. A more basic comparison table is available below.
| Rated Voltage |
Motor Type |
Stall Current |
No-Load Current |
Gear Ratio | No-Load Speed (RPM) |
Extrapolated Stall Torque |
Max Power (W) |
 Without Encoder |
 With Encoder |
|
|---|---|---|---|---|---|---|---|---|---|---|
| (kg ⋅ cm) | (oz ⋅ in) | |||||||||
| 12 V | High-Power (HP) |
5.0 A | 250 mA w/o encoder 300 mA with encoder |
1:1 (no gearbox) | 10,000 | 0.4 | 5.5 | 10 | – | item #4840 |
| 4.4:1 | 2200 | 1.7 | 24 | 9.4 | item #3201 | item #4841 | ||||
| 9.7:1 | 1000 | 3.9 | 54 | 10 | item #3202 | item #4842 | ||||
| 20.4:1 | 500 | 7.4 | 100 | 9.4 | item #3203 | item #4843 | ||||
| 34:1 | 300 | 11 | 150 | 8.9 | item #3204 | item #4844 | ||||
| 47:1 | 220 | 15 | 210 | 8.4 | item #3205 | item #4845 | ||||
| 75:1 | 130 | 22 | 310 | – | item #3206 | item #4846 | ||||
| 99:1 | 100 | 29 | 400 | – | item #3207 | item #4847 | ||||
| 12 V | Medium-Power (MP) |
1.8 A | 80 mA w/o encoder 100 mA with encoder |
1:1 (no gearbox) | 8200 | 0.17 | 2.4 | 3.5 | – | item #4860 |
| 4.4:1 | 1800 | 0.71 | 10 | 3.2 | item #3225 | item #4861 | ||||
| 9.7:1 | 800 | 1.7 | 24 | 3.4 | item #3226 | item #4862 | ||||
| 20.4:1 | 380 | 3.2 | 44 | 3.1 | item #3227 | item #4863 | ||||
| 34:1 | 230 | 4.7 | 65 | 2.8 | item #3228 | item #4864 | ||||
| 47:1 | 170 | 6.4 | 89 | 2.8 | item #3229 | item #4865 | ||||
| 75:1 | 100 | 8.5 | 120 | 2.3 | item #3230 | item #4866 | ||||
| 99:1 | 79 | 11 | 150 | 2.3 | item #3231 | item #4867 | ||||
| 172:1 | 46 | 18 | 250 | 2.1 | item #3232 | item #4868 | ||||
| 227:1 | 35 | 24 | 330 | – | item #3233 | item #4869 | ||||
| 12 V | Low-Power (LP) |
0.9 A | 50 mA w/o encoder 60 mA with encoder |
1:1 (no gearbox) | 5600 | 0.14 | 1.9 | 1.8 | – | item #4880 |
| 4.4:1 | 1200 | 0.53 | 7.4 | 1.7 | item #3249 | item #4881 | ||||
| 9.7:1 | 580 | 1.3 | 18 | 1.8 | item #3250 | item #4882 | ||||
| 20.4:1 | 280 | 2.4 | 33 | 1.7 | item #3251 | item #4883 | ||||
| 34:1 | 170 | 3.7 | 51 | 1.6 | item #3252 | item #4884 | ||||
| 47:1 | 120 | 4.8 | 67 | 1.4 | item #3253 | item #4885 | ||||
| 75:1 | 75 | 7.1 | 99 | 1.4 | item #3254 | item #4886 | ||||
| 99:1 | 57 | 8.7 | 120 | 1.2 | item #3255 | item #4887 | ||||
| 172:1 | 33 | 13 | 180 | 1.1 | item #3256 | item #4888 | ||||
| 227:1 | 25 | 16 | 220 | 1.0 | item #3257 | item #4889 | ||||
| 378:1 | 15 | 23 | 320 | – | item #3258 | item #4890 | ||||
| 6 V | High-Power (HP) |
6.0 A | 420 mA w/o encoder 500 mA with encoder |
1:1 (no gearbox) | 10,000 | 0.3 | 4 | 7 | – | item #4800 |
| 4.4:1 | 2200 | 1.2 | 17 | 6.7 | item #1570 | item #4801 | ||||
| 9.7:1 | 1000 | 2.3 | 32 | 5.9 | item #1571 | item #4802 | ||||
| 20.4:1 | 480 | 4.8 | 67 | 5.9 | item #1572 | item #4803 | ||||
| 34:1 | 290 | 6.8 | 94 | 5.1 | item #1573 | item #4804 | ||||
| 47:1 | 210 | 9.1 | 130 | 4.9 | item #1574 | item #4805 | ||||
| 75:1 | 130 | 14 | 190 | 4.5 | item #1575 | item #4806 | ||||
| 99:1 | 99 | 15 | 210 | 3.9 | item #1576 | item #4807 | ||||
| 172:1 | 57 | 27 | 380 | – | item #1577 | item #4808 | ||||
| 6 V | Low-Power (LP) |
2.0 A | 100 mA w/o encoder 120 mA with encoder |
1:1 (no gearbox) | 6200 | 0.15 | 2.1 | 2.1 | – | item #4820 |
| 4.4:1 | 1300 | 0.63 | 8.7 | 2.1 | item #1581 | item #4821 | ||||
| 9.7:1 | 630 | 1.3 | 18 | 1.9 | item #1582 | item #4822 | ||||
| 20.4:1 | 290 | 2.5 | 35 | 1.9 | item #1583 | item #4823 | ||||
| 34:1 | 180 | 3.9 | 54 | 1.7 | item #1584 | item #4824 | ||||
| 47:1 | 130 | 4.8 | 67 | 1.5 | item #1585 | item #4825 | ||||
| 75:1 | 80 | 7.5 | 100 | 1.5 | item #1586 | item #4826 | ||||
| 99:1 | 61 | 9.1 | 130 | 1.4 | item #1587 | item #4827 | ||||
| 172:1 | 35 | 14 | 190 | 1.2 | item #1588 | item #4828 | ||||
| 227:1 | 27 | 17 | 240 | 1.1 | item #1589 | item #4829 | ||||
| 378:1 | 16 | 25 | 350 | – | item #1590 | item #4830 | ||||
| 499:1 | 12 | 31 | 430 | – | item #1591 | item #4831 | ||||
Note: The listed stall torques and currents are theoretical extrapolations; units will typically stall well before these points as the motors heat up. Stalling or overloading gearmotors can greatly decrease their lifetimes and even result in immediate damage. The recommended upper limit for continuously applied loads is 4 kg⋅cm (55 oz⋅in), and the recommended upper limit for intermittently permissible torque is 8 kg⋅cm (110 oz⋅in). 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.
In general, these kinds of motors can run at voltages above and below their nominal voltages (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.
Exact gear ratio: ``(22×22×22×22×22×22×24) / (12×10×10×10×10×10×10) ~~ bb(226.76:1)``
The diagram below shows the dimensions of the 25D mm line of gearmotors (units are mm over [inches]). This diagram is also available as a downloadable PDF (171k pdf).
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Dimensions of the Pololu 25D mm metal gearmotors without encoders. Units are mm over [inches]. |
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Warning: Do not screw too far into the mounting holes as the screws can hit the gears. We recommend screwing no further than 6 mm (0.24″) into the screw hole.
The face plate has two mounting holes threaded for M3 screws. You can use our custom-designed 25D mm metal gearmotor bracket (shown in the picture below) to mount the gearmotor to your project via these mounting holes and the screws that come with the bracket.
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The 4 mm diameter gearbox output shaft works with Pololu multi-hub wheels as shown in the left picture below. That shaft also works with the Pololu universal aluminum mounting hub for 4mm shafts, which can be used to mount our larger Pololu wheels (60mm-, 70mm-, 80mm-, and 90mm-diameter) or custom wheels and mechanisms to the gearmotor’s output shaft as shown in the right picture below.
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Alternatively, you could use our 4mm scooter wheel adapter to mount many common scooter, skateboard, and inline skate wheels to the gearmotor’s output shaft as shown in the left picture below. For a general-purpose hex adapter, consider our 12mm hex wheel adapter, which lets you use this motor with many common hobby RC wheels as shown in the right picture below.
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These are the same type of motors used in the Wild Thumper all-terrain chassis, so the gearbox’s output shaft also works directly with the hex adapters included with the 120mm-diameter Wild Thumper wheels as shown in the image below:
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Dagu Wild Thumper wheel 120×60mm (metallic red) and Pololu 25D mm metal gearmotor with encoder. |
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We have a number of motor drivers and motor controllers that work with these 25D mm metal gearmotors. For the LP and MP versions, we recommend our TB9051FTG-based drivers, for which we have a basic single carrier, a dual-channel shield for Arduino, and a dual-channel expansion board for Raspberry Pi. For the HP versions, we recommend our VNH5019-based motor drivers (available as single and dual carriers), though these can also be a good choice for the lower-power motors.
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If you are looking for higher-level control interfaces, such as USB, RC, analog voltages, I²C, or TTL serial, consider our Simple Motor Controllers, Jrk motor controllers, or RoboClaw motor controllers; these controllers are available in various power levels, and the appropriate one depends on the particular version of 25D mm motor you have (we generally recommend a motor controller that can handle continuous currents above the stall current of your motor).
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We have an assortment of Hall effect-based current sensors to choose from for those who need to monitor motor current:
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We offer a wide selection of metal gearmotors that offer different combinations of speed and torque. Our metal gearmotor comparison table can help you find the motor that best meets your project’s requirements.
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| Size: | 25D x 56L mm1 |
|---|---|
| Weight: | 94 g |
| Shaft diameter: | 4 mm2 |
| Gear ratio: | 226.76:1 |
|---|---|
| No-load speed @ 12V: | 25 rpm3 |
| No-load current @ 12V: | 0.050 A4 |
| Stall current @ 12V: | 0.90 A5 |
| Stall torque @ 12V: | 16 kg·cm5 |
| Max output power @ 12V: | 1.0 W |
| No-load speed @ 6V: | 13 rpm6 |
| Stall current @ 6V: | 0.45 A6 |
| Stall torque @ 6V: | 8.0 kg·cm6 |
| Motor type: | 12V, 0.9A stall (LP 12V) |
| Max efficiency @ 12V: | 30 % |
|---|---|
| Speed at max efficiency: | 21 rpm |
| Torque at max efficiency: | 2.4 kg·cm |
| Current at max efficiency: | 0.14 A |
| Output power at max efficiency: | 0.53 W |
| Encoders?: | N |
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This file contains 3D models (in the step file format) of the 25D mm gearmotors with and without encoders.
No! Stalls can 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, which means keeping continuously applied loads around 25% or less of the stall torque.
Additionally, for many of our gearmotors with high gear ratios, the extrapolated stall torque is beyond what the gearboxes are designed to handle, and a stall could instantly damage the gears. Make sure to keep applied loads within the published limits for your gearmotor.
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