These tiny brushed DC gearmotors are available in a wide range of gear ratios—from 5:1 up to 1000:1—and with five different motors: high-power 6 V and 12 V motors with long-life carbon brushes (HPCB), and high-power (HP), medium power (MP), and low power (LP) 6 V motors with shorter-life precious metal brushes. The 6 V and 12 V HPCB motors offer the same performance at their respective nominal voltages, just with the 12 V motor drawing half the current of the 6 V motor. The 6 V HPCB and 6 V HP motors are identical except for their brushes, which only affect the lifetime of the motor.
The HPCB versions (shown on the left in the picture below) can be differentiated from versions with precious metal brushes (shown on the right) by their copper-colored terminals. Note that the HPCB terminals are 0.5 mm wider than those on the other micro metal gearmotor versions (2 mm vs. 1.5 mm), and they are about 1 mm closer together (6 mm vs. 7 mm).
Versions of these gearmotors are also available with an additional 1 mm-diameter output shaft that protrudes from the rear of the motor. This 4.5 mm-long rear shaft rotates at the same speed as the input to the gearbox and offers a way to add an encoder, such as our magnetic encoder for micro metal gearmotors (see the picture on the right), to provide motor speed or position feedback.
With the exception of the 1000:1 gear ratio versions, all of the micro metal gearmotors have the same physical dimensions, so one version can be easily swapped for another if your design requirements change.
Please see the micro metal gearmotor datasheet (2MB pdf) for more information, including detailed performance graphs for each micro metal gearmotor version. You can also use our dynamically sortable micro metal gearmotor comparison table for search for the gearmotor that offers the best blend of speed, torque, and current-draw for your particular application. A more basic comparison table is available below.
Note: Stalling or overloading gearmotors can greatly decrease their lifetimes and even result in immediate damage. The recommended upper limit for instantaneous torque is 35 oz-in (2.5 kg-cm) for the 1000:1 gearboxes and 25 oz-in (2 kg*cm) for all the other gear ratios; . Stalls can also result in rapid (potentially on the order of seconds) thermal damage to the motor windings and brushes, especially for the versions that use high-power (HP and HPCB) motors; 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; lower voltages might not be practical, and higher voltages could start negatively affecting the life of the motor.
Details for item #998
Exact gear ratio: ``(32×33×35×38) / (15×14×13×10) ~~ bb(51.45:1)``
In terms of size, these gearmotors are very similar to Sanyo’s popular 12 mm NA4S DC gearmotors, and gearmotors with this form factor are occasionally referred to as N20 motors. The versions with carbon brushes (HPCB) have slightly different terminal and end-cap dimensions than the versions with precious metal brushes, but all of the other dimensions are identical.
Dimensions of versions with carbon brushes (HPCB)
Dimensions of the Pololu micro metal gearmotors with carbon brushes (HPCB). Units are mm over [inches].
Dimensions of versions with precious metal brushes (LP, MP, and HP)
Dimensions of the Pololu micro metal gearmotors with precious metal brushes: low-power (LP), medium-power (MP), and high-power (HP). Units are mm over [inches].
These diagrams are also available as a downloadable PDF (262k pdf).
Pololu wheel 32×7mm on a micro metal gearmotor.
Black Pololu 70×8mm wheel on a Pololu micro metal gearmotor.
A pair of Pololu universal aluminum mounting hubs for 3 mm diameter shafts.
12mm Hex Wheel Adapter for 3mm Shaft on a Micro Metal Gearmotor.
Black micro metal gearmotor mounting bracket pair with included screws and nuts.
White micro metal gearmotor mounting bracket pair with included screws and nuts.
Pololu micro metal gearmotor bracket extended with micro metal gearmotor.
- Quadrature encoders: We offer several quadrature encoders that work with our micro metal gearmotors.
Magnetic Encoder Kit for Micro Metal Gearmotors assembled with ribbon cable wires.
Example of an installed micro metal gearmotor reflective optical encoder.
Note: The HPCB versions of our micro metal gearmotors are not compatible with our #2590 and #2591 optical encoders or our older #2598 magnetic encoders (the terminals are too wide to fit through the corresponding holes in the encoder boards). However, they are compatible with our newer #3081 magnetic encoders.
DRV8838 Single Brushed DC Motor Driver Carrier.
Pololu A4990 Dual Motor Driver Shield for Arduino, bottom view.
DRV8835 dual motor driver carrier.
- Current sensors: We have an assortment of Hall effect-based current sensors to choose from for those who need to monitor motor current:
ACS711EX current sensor carrier -15.5A to +15.5A.
ACS714 current sensor carrier -5A to +5A.
We also incorporate these motors into some of our products, including our Zumo robot and 3pi robot :
Assembled Zumo 32U4 robot.
Pololu 3pi robot.
Selecting the Right Gearmotor
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.
Some of the Pololu metal gearmotors.
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