This tiny, cylindrical gearmotor consists of a coreless brushed DC motor and a 136:1 plastic planetary gearbox. The entire assembly has a diameter of just 6 mm (0.24″) and an extremely light weight of 1.25 g (0.044 oz), making it a great actuator for miniature robots and very small mechanisms.Key specs at 6 V: 500 RPM and 45 mA free-run, 8 oz-in (0.6 kg-cm) and 400 mA stall.

26:1 sub-micro plastic planetary gearmotor next to a micro metal gearmotor and a LEGO Minifigure for size reference.

Sub-micro plastic planetary gearmotors. Gear ratios from top to bottom: 700:1, 136:1, 26:1.

These tiny brushed DC gearmotors have a diameter of just 6 mm and weigh just over a gram, which makes them great actuators for miniature robots and very small mechanisms. They consist of a coreless motor fastened to a planetary gearbox by a small clip. The gears are made from liquid crystal polymers (LCPs), and gearbox’s nylon output shaft is compatible with our 14 mm wheels. Three gear ratios are available:

26:1, which has a free run speed of 2500 RPM and stall torque of 1.5 oz-in (110 g-cm) at 6 V

136:1, which has a free run speed of 500 RPM and stall torque of 8 oz-in (550 g-cm) at 6 V

700:1, which has a free run speed of 90 RPM and stall torque of 12 oz-in (900 g-cm) at 6 V

Note: Stalling or overloading gearmotors can greatly decrease their lifetimes and even result in immediate damage. For these gearboxes, the recommended upper limit for instantaneous torque is 3.5 oz-in (250 g-cm); we strongly advise keeping applied loads well under this limit. Stalls can also result in rapid (potentially on the order of seconds) thermal damage to the motor windings and brushes; a general recommendation for brushed DC motor operation is 25% or less of the stall current.

The intended nominal operating voltage for these motors is 3 V to 6 V, though in general, these kinds of motors can be used at voltages outside this range (rotation typically starts between 0.2 V and 0.3 V). Lower voltages might not be practical, and higher voltages could start negatively affecting the life of the motor. When operating at 3 V, the free-run speed, stall torque, and stall current will all be approximately half of what they are at 6 V as these specifications scale roughly linearly with voltage.

Since the gearmotor’s output shaft is nylon, there can be small variances in the diameter from unit to unit. These variations might cause press-fit attachments like our 14 mm wheel to fit loosely in some instances. If you experience a loose fit, you could try swapping wheels or using a small dab of glue to help hold the wheel on.

The following diagram shows the micro plastic gearmotor dimensions in mm. The planetary gearbox has a D-shaped plastic output shaft, which is 2 mm in diameter with a section that is flattened by 0.5 mm. The “D” portion of the shaft is 2.5 mm long. The motor measures 6 mm in diameter and 9.3 mm in length, and the gearbox length, labeled “L” in the diagram below, depends on the gear ratio.

Dimensions of the Sub-Micro Plastic Planetary Gearmotors. Units are mm over [inches].

This dimension diagram is also available as a downloadable PDF (92k pdf).

These motors originally shipped with leads that extended approximately 2 cm (0.8″) from the back of the motor, but we began transitioning to shipping units with much longer leads (approximately 12.5 cm, or 5″) in January, 2017. These leads are pre-stripped and unterminated (i.e. they do not end in a connector).

The micro plastic gearmotor’s output shaft is compatible with our 14 mm wheels. We do not have any brackets for this gearmotor, and it does not have any mounting holes, but its compact size makes it easy to fasten with tape or glue. Alternatively, since this gearmotor is nearly the same size as a 1/4″ fuse, it can be mounted using standard 1/4″ (6 mm) fuse clips, which can be found at places like Radio Shack and Digi-Key.

Sub-micro plastic planetary gearmotor with a 14×4.5mm wheel.

26:1 sub-micro plastic planetary gearmotor being held by a 1/4″ (6 mm) fuse clip.

People often buy this product together with:

This 200:1 gearbox with brushed DC motor has a low-current motor and provides power and speed that is comparable to an RC servo at a fraction of the cost. At 6 V, it has a free-run speed of 51 RPM and a stall torque of approximately 100 oz-in. Though the product picture shows two gearmotors, this product is for a single motor.

Pololu plastic gearmotor 90 deg. output with opened gearbox.

This 200:1 plastic gearmotor (gearbox with brushed DC motor) is a great low-cost alternative to modified hobby servos or Tamiya gearboxes. The low-current motor is a perfect match for our qik 2s9v1 dual serial motor controller, Baby Orangutan robot controller, or DRV8833 dual motor driver carrier, and the compact size makes this unit an attractive choice for small robot designs. The recommended operating voltage range for this motor is 3 – 12 V.

This is a higher-torque, lower-speed version of the 120:1 plastic gearmotor 90-degree output. At 6 V, the gearbox and motor provide approximately 100 oz-in of torque and 51 RPM. The free-running current is 70 mA, and the stall current is 800 mA. The gearbox is protected by a built-in safety clutch that will typically slip before gear teeth can shear.

This gearmotor comes pre-assembled, with the gears fully enclosed, and the output shaft is 6 mm long and 7 mm in diameter with two sides flattened. The output shaft is at a 90° angle from the axis of the motor shaft; we also sell a similar gearmotor with an offset output shaft.

There are two built-in mounting holes that work with our stamped aluminum L-bracket and extended stamped aluminum L-bracket, as shown in the pictures below:

Plastic gearmotor with 90-degree output (item #1120 or #1121) mounted with Pololu stamped aluminum L-bracket.

Plastic gearmotor with 90-degree output (item #1120 or #1121) mounted with Pololu extended stamped aluminum L-bracket.

A custom-molded GMPW plastic wheel for this gearmotor is available in a variety of colors.

Dimensions (in mm) of the 120:1 and 200:1 plastic gearmotors with 90-degree outputs.

You can download a pdf version of this drawing here (104k pdf).

People often buy this product together with: