These small brushed DC gearmotors can deliver a lot of power for their size. This version has a 154:1 metal gearbox with a 0.276"-long, 4 mm-diameter D-shaped output shaft.
Key specs at 6 V: 90 RPM and 250 mA free-run, 120 oz-in (8.6 kg-cm) and 3.3 A stall.
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The 20D mm line of brushed DC gearmotors all have the same dimensions except for the length of the gearbox, and they are intended for use at 6 V. 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. Higher voltages could start negatively affecting the life of the motor, and lower voltages might not be practical. Four different gear ratios are available:
|Gear Ratio||No-Load Speed
@ 6 V
@ 6 V
@ 6 V
@ 6 V
|29:1||450 RPM||250 mA||25 oz-in||3.3 A|
|56:1||250 RPM||250 mA||45 oz-in||3.3 A|
|73:1||180 RPM||250 mA||60 oz-in||3.3 A|
|154:1||90 RPM||250 mA||120 oz-in||3.3 A|
Note: Stalling gearmotors can greatly decrease their lifetimes, occasionally resulting in immediate damage to the gearbox. This is especially true for the higher gear ratios, which can generate enough torque to damage themselves. Prolonged stalls (on the order of seconds) can result in thermal damage to the motor windings and brushes.
The gearmotor face plate has two mounting holes threaded for M2.5 screws, and you can use our custom-designed 20D mm metal gearmotor bracket (shown in the left picture below) to mount the gearmotor to your project via these mounting holes and the screws that come with the bracket.
This gearmotor has an output shaft with a diameter of 4 mm; the Pololu universal aluminum mounting hubs for 4mm shafts 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 (see the right picture above). 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. The gearbox’s output shaft also works directly with the 120mm-diameter Wild Thumper wheels, as shown below.
|Dagu Wild Thumper wheel 120×60mm (metallic red) with Pololu 20D mm metal gearmotor.|
The picture below shows the dimensions (in mm) of the 20D mm line of gearmotors. The value of L depends on the gear ratio of the gearbox: 29:1 is 15.7 mm, 56:1 and 73:1 is 17.2 mm, and 154:1 is 18.6 mm.
|20D mm metal gearmotor dimensions (units in mm; L depends on gear ratio).|
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.|
People often buy this product together with:
|Pololu Universal Aluminum Mounting Hub for 4mm Shaft, #4-40 Holes (2-Pack)|
|Pololu 20D mm Metal Gearmotor Bracket Pair|
|73:1 Metal Gearmotor 20Dx42L mm|