120:1 Mini Plastic Gearmotor, 90° 2mm Spline Output

Gears inside the mini plastic gearmotor with 90 degree output (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 Pololu 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 #1123

Exact gear ratio: 22×38×44×26×3010×11×11×22×9≈119.76" role="presentation" style="position: relative;">22×38×44×26×3010×11×11×22×9˜119.76$\frac{22\times 38\times 44\times 26\times 30}{10\times 11\times 11\times 22\times 9}˜119.76$

Dimensions

Dimension diagram of the mini plastic gearmotor with 90° 2mm spline output (units are mm over [in]).

This dimension diagram is also available as a downloadable pdf (75k 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 Pololu's adapter for LEGO wheels. The gearbox output shaft is perpendicular to the motor shaft.

Gearmotor Versions

Pololu 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.

Pololu have many more versions of these mini plastic gearmotors available with 3 mm diameter “D”-shaped output shafts (just like the ones on Pololu's micro metal gearmotors) that are compatible with many Pololu wheels and Pololu's 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	StallCurrent@ 4.5 V	No-LoadSpeed@ 4.5 V	Stall Torque@ 4.5 V	90° output	90° output + motor shaft	offset output	offset output + motor shaft
high-power(HP)	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: Pololu's 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: Pololu 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 Pololu's 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.

• Motor drivers: Pololu 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. Pololu 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 Pololu's 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.

DRV8835 dual motor driver carrier.

DRV8838 Single Brushed DC Motor Driver Carrier.

MAX14870 Single Brushed DC Motor Driver Carrier.

People often buy this product together with:

2mm Shaft Adapter for LEGO Wheels (Pair)

200:1 Plastic Gearmotor, 90° Output

120:1 Plastic Gearmotor, 90° Output

Dimensions

General specifications

Notes:

1

See drawing for detailed dimensions.

2

Measurement is diameter of spline crest.

3

Note: the gearbox's built-in clutch might start slipping at a lower torque.

File downloads

• dimension diagram: 90° 2mm spline version (75k pdf)

  Dimension diagram of the mini plastic gearmotor with 90° 2mm spline output.

Recommended links

• MATLAB script to plot motor performance curves for Pololu brushed DC gearmotors

  This MATLAB script, written by Ali Asgher Mansoor Habiby, plots speed, power, current draw, and efficiency as they vary with torque when you input the gearmotor specifications. It also prints the resistance of the motor, and the current draw and torque at which maximum efficiency and maximum power occur.