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This compact, inexpensive plastic gearmotor (high-power
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 gearbox has a 9.7mm-long,
3 mm-diameter D-shaped output shaft that is perpendicular to the motor
shaft, and a built-in safety clutch helps protect the gears from
excessive loads. This version also has a 5x 1.5 mm extended motor shaft.
Key specs at 4.5 V: 150 RPM and 130 mA free-run, 25 oz-in (1.8 kg-cm) and 1.25 A stall.
These brushed DC gearmotors are compact and affordable — 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 0.5 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).
The mini plastic gearmotor family offers 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). The 120:1 versions are white and the 180:1 versions are yellow:
Some versions of these gearmotors are also available with an additional 1.5 mm-diameter output shaft that protrudes from the rear of the motor. This 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 mini plastic gearmotors, to provide motor speed or position feedback:
Please see the mini plastic gearmotor comparison table for detailed specifications of all our mini plastic 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.
This item has a high-power motor (1250 mA stall current), a 120:1
gearbox, and a 3 mm diameter “D”-shaped output shaft that is offset from
but parallel to the motor shaft. The 1.5 mm diameter motor shaft
extends approximately 5 mm past the base of the motor. See the dimension diagram (69k pdf) of this gearmotor for more information.
- Product Wiki
- dimension diagram: 90Â° 3mm D-shaft version: Dimension diagram of the mini plastic gearmotor with 90Â° 3mm D-shaft output.
- dimension diagram: 90Â° 3mm D-shaft and extended motor shaft version: Dimension diagram of the mini plastic gearmotor with 90Â° 3mm D-shaft output and extended motor shaft.
- dimension diagram: 90Â° 3mm D-shaft and extended motor shaft version HP: Dimension diagram of the mini plastic gearmotor HP with 90Â° 3mm D-shaft output and extended motor shaft.
- dimension diagram: offset 3mm D-shaft version: Dimension diagram of the mini plastic gearmotor with offset 3mm D-shaft output.
- dimension diagram: offset 3mm D-shaft and extended motor shaft version: Dimension diagram of the mini plastic gearmotor with offset 3mm D-shaft output and extended motor shaft.
- dimension diagram: offset 3mm D-shaft and extended motor shaft version HP: Dimension diagram of the mini plastic gearmotor HP with offset 3mm D-shaft output and extended motor shaft.
- 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.
- New product: Magnetic Encoder Pair Kit for Mini Plastic Gearmotors: We now have a magnetic encoder pair kit available for our mini plastic gearmotors with extended back shafts. Like our encoder kit for micro metal...
- New products: Six new Mini Plastic Gearmotors: Our family of Mini Plastic Gearmotors is growing! We have added HP versions with more powerful motors for increased torque and speed, and we are...
120:1 Mini Plastic Gearmotor HP, Offset 3mm D-Shaft Output, Extended Motor Shaft - High Power 
- Brand: Pololu
- Product Code: POL-1520
- Reward Points: 7
- Availability: 2
- Ex Tax: £7.95
- Price in reward points: 100