120:1 Mini Plastic Gearmotor, Offset 2mm Spline Output

Pololu item #: 1122
Brand: PCX
Status: Special Order Only 
RoHS 3 compliant

This product has been discontinued.

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.

Key specifications:

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? Select variant…

 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.

Gearmotor Versions

We carry two versions of mini plastic gearmotors with 2 mm diameter spline output shafts, one with an offset shaft and one with a 90° 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:

Motor Type Stall
@ 4.5 V
@ 4.5 V
Stall Torque
@ 4.5 V

90° output

90° output + motor shaft

offset output

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.

Motor Accessories

  • 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.

Mini Plastic Gearmotor Bracket Pair – Wide.

Mini Plastic Gearmotor Bracket Pair – Tall.

  • 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.

Pololu qik 2s9v1 dual serial motor controller (older version with large silver electrolytic capacitor).

Baby Orangutan B-48/B-168/B-328.

DRV8835 dual motor driver carrier.

DRV8838 Single Brushed DC Motor Driver Carrier.

MAX14870 Single Brushed DC Motor Driver Carrier.

Related Products

DRV8835 Dual Motor Driver Carrier
DRV8838 Single Brushed DC Motor Driver Carrier
DRV8833 Dual Motor Driver Carrier
MAX14870 Single Brushed DC Motor Driver Carrier
TB6612FNG Dual Motor Driver Carrier
Baby Orangutan B-328 Robot Controller

Related Categories

Mini Plastic Gearmotors
Motors and Gearboxes
Solarbotics Wheels
Brushed DC Motor Controllers
Brushed DC Motor Drivers
Robot Controllers
Pololu Metal Gearmotors
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