120:1 Mini Plastic Gearmotor, Offset 2mm Spline Output
This compact, inexpensive, low-current gearmotor (brushed DC motor with a 120:1 reduction gearbox) is well suited for use in small robots. While intended for operation at 4.5 V, it should run comfortably in the 3 V to 6 V range. The splined output shaft has a crest diameter of 2 mm and is offset from but parallel to the motor shaft. The gearbox is protected by a built-in safety clutch that helps protect the gears from excessive loads.
|voltage||no-load performance||stall extrapolation|
|4.5 V||120 RPM, 80 mA||1.4 kg⋅cm (20 oz⋅in), 800 mA|
Alternatives available with variations in these parameter(s): shaft type no-load speed @ 4.5V extended motor shaft?
|Description||Specs (11)||Pictures (6)||Resources (2)||FAQs (1)||On the blog (0)|
Gears inside the mini plastic gearmotor with offset output shaft (2mm spline version).
This brushed DC gearmotor is very compact and weighs only 0.7 ounces (19.5 grams) — perfect for building a quick, miniature robot. They are intended for use at 4.5 V, though in general, these kinds of motors can run at voltages above and below this nominal voltage, so they should operate comfortably in the 3 V to 6 V range (rotation can start at voltages as low as 0.6 V). Lower voltages might not be practical, and higher voltages could start negatively affecting the life of the motor. The plastic gearbox is protected by a built-in safety clutch that will typically slip before the gear teeth can shear (typically when the load exceeds around 25 oz-in, or 2 kg-cm).
Details for item #1122
Exact gear ratio: ``(22×38×44×26×30) / (10×11×11×22×9) ~~ bb(119.76)``
Dimension diagram of the mini plastic gearmotor with offset 2mm spline output (units are mm over [in]).
This dimension diagram is also available as a downloadable pdf (76k pdf).
This gearmotor features a splined, chrome-finish output shaft with a 2mm-crest diameter. This shaft can be used with custom wheels or with our adapter for LEGO wheels. The gearbox output shaft is offset from but parallel to the motor shaft.
We have many more versions of these mini plastic gearmotors available with 3 mm diameter “D”-shaped output shafts (just like the ones on our micro metal gearmotors) that are compatible with many Pololu wheels and our 3 mm universal mounting hubs. These versions offer two output shaft orientations relative to the motor shaft (offset and 90°), two motor options (normal and high-power, or HP for short), and two gearbox options (120:1 and 180:1). Additionally, some of these versions are available with an extended motor shaft that protrudes from the rear of the motor by approximately 4.5 mm. This second shaft has a diameter of 1.5 mm and rotates at the same speed as the input to the gearbox, offering a way to add a custom-built encoder to provide motor speed or position feedback. The following table shows all of the mini plastic gearmotors that have 3 mm D-shafts:
@ 4.5 V
@ 4.5 V
@ 4.5 V
90° output + motor shaft
offset output + motor shaft
|1250 mA||150 RPM||25 oz-in||120:1 mini HP||120:1 mini HP||120:1 mini HP||120:1 mini HP|
|low-power||800 mA||120 RPM||20 oz-in||120:1 mini||120:1 mini||120:1 mini||120:1 mini|
|80 RPM||30 oz-in||180:1 mini||180:1 mini|
Note: The stall torque values listed are approximate, and the built-in safety clutch might start slipping at lower torques.
- Mounting brackets: Our wide and tall mounting brackets are specifically designed to securely mount these mini plastic gearmotors. Both brackets work with both offset and 90° gearmotor versions, and the two brackets each allow for different mounting options.
- Motor controllers: We offer a number of motor controllers that make it easy to drive these mini plastic gearmotors.
- The Qik 2s9v1 Dual Serial Motor Controller allows variable speed and direction control of two small, brushed DC motors using a simple serial interface. An Arduino library is available to make communication easier and multiple units can be daisy-chained together if you need to independently control many motors from a single serial bus.
- The programmable Baby Orangutan B-328 Robot Controller combines a programmable ATmega328P AVR microcontroller and dual motor driver all in a single, very compact, package and makes interfacing with the motor drivers simple when you use our Pololu AVR library.
- Motor drivers: We also carry a number of basic motor drivers suitable for use with these motors.
- The DRV8835 Dual Motor Driver Carrier is a great option for driving 2 of these mini plastic gearmotors, especially if space is limited. Aside from its tiny size, it has the benefit of supporting two control interfaces: IN/IN and PHASE/ENABLE. We also carry a DRV8835 dual motor driver shield that makes it easy to incorporate this driver into an Arduino project, as well a DRV8835 motor driver kit for the Raspberry Pi.
- The DRV8838 Single Brushed DC Motor Driver Carrier is essentially a smaller, lower-cost, single-channel alternative to our DRV8835 carrier.
- The MAX14870 Single Brushed DC Motor Driver Carrier is another great single-channel alternative that also offers optional current limiting. This driver is also available as Dual MAX14870 motor driver shield for Arduino and a Dual MAX14870 motor driver kit for the Raspberry Pi to make it easy to incorporate into a two-motor application.
People often buy this product together with:
|2mm Shaft Adapter for LEGO Wheels (Pair)|
|228:1 Plastic Gearmotor, Offset Output|
|120:1 Plastic Gearmotor, Offset Output|