These tiny brushed DC gearmotors are intended for use at 6 V, though in general, these kinds of motors can run at voltages above and below this nominal voltage, so they should comfortably operate in the 3 – 9 V range (rotation can start at voltages as low as 0.5 V). Lower voltages might not be practical, and higher voltages could start negatively affecting the life of the motor. The micro metal gearmotors are available in a wide range of gear ratios—from 5:1 up to 1000:1—and with four different motors: high-power with long-life carbon brushes (HPCB), high-power with shorter-life precious metal brushes (HP), medium-power (MP), and low-power. The HPCB version (shown on the left in the picture below) can be differentiated from versions with precious metal brushes (shown on the right) by its 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).
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 comparison table for detailed specifications of all our micro metal gearmotors. This dynamically-sortable table can help you find 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.
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.
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.
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 (low-power, MP, and HP)
|Dimensions of the Pololu micro metal gearmotors with precious metal brushes: low-power, 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.|
- Quadrature encoders: We offer several quadrature encoders that work with our micro metal gearmotors.
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.
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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