Pololu 998 - 50:1 Micro Metal Gearmotor HP

Overview

These tiny brushed DC gearmotors are intended for use at 6 V, though in general, these kinds of motors can run at voltages above and below this nominal voltage, so they should comfortably operate in the 3 – 9 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 micro metal gearmotors are available in a wide range of gear ratios—from 5:1 up to 1000:1—and offer a choice between two different motors: high-power (HP) and standard. With the exception of the 1000:1 gear ratio versions, all of the micro metal gearmotors have the same physical dimensions, so one version can be easily swapped for another if your design requirements change. Please see the micro metal gearmotor comparison table for detailed specifications of all our micro metal 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. A more basic comparison table is available below.

Some versions of the gearmotors are sold with an additional 1mm-diameter output shaft that protrudes from the rear of the motor. This 4.5mm-long rear shaft rotates at the same speed as the input to the gearbox and offers a way to add a custom-built encoder to provide motor speed or position feedback.

Gear Ratio	Speed @ 6V	Stall Torque @ 6V	Stall Current @ 6V	Gearbox Shaft Only	Gearbox & Motor Shaft
5:1	6000 RPM	2 oz-in	1600 mA	5:1 micro HP
	2500 RPM	1 oz-in	360 mA	5:1 micro
10:1	3000 RPM	4 oz-in	1600 mA	10:1 micro HP	10:1 micro HP
	1300 RPM	2 oz-in	360 mA	10:1 micro
30:1	1000 RPM	9 oz-in	1600 mA	30:1 micro HP	30:1 micro HP
	440 RPM	4 oz-in	360 mA	30:1 micro	30:1 micro
50:1	625 RPM	15 oz-in	1600 mA	50:1 micro HP	50:1 micro HP
	250 RPM	7 oz-in	360 mA	50:1 micro	50:1 micro
75:1	400 RPM	22 oz-in	1600 mA	75:1 micro HP
	170 RPM	9 oz-in	360 mA	75:1 micro
100:1	320 RPM	30 oz-in	1600 mA	100:1 micro HP	100:1 micro HP
	120 RPM	12 oz-in	360 mA	100:1 micro	100:1 micro
150:1	200 RPM	40 oz-in	1600 mA	150:1 micro HP
	85 RPM	17 oz-in	360 mA	150:1 micro
210:1	140 RPM	50 oz-in	1600 mA	210:1 micro HP
	60 RPM	27 oz-in	360 mA	210:1 micro
250:1	120 RPM	60 oz-in	1600 mA	250:1 micro HP
	50 RPM	32 oz-in	360 mA	250:1 micro
298:1	100 RPM	70 oz-in	1600 mA	298:1 micro HP	298:1 micro HP
	45 RPM	40 oz-in	360 mA	298:1 micro	298:1 micro
1000:1	32 RPM	125 oz-in	1600 mA	1000:1 micro HP
	14 RPM	70 oz-in	360 mA	1000:1 micro

Note: The 1000:1 gearmotors can generate enough torque to damage themselves. The stall torque values given for those two motors are theoretical, and we strongly recommend you avoid stalling them.

Gearmotor Dimensions

Micro metal gearmotor dimensions (units in mm).

The gearbox has a long (0.365" or 9.27 mm), 3 mm-diameter D-shaped metal output shaft, and the brass faceplate has two mounting holes threaded for M1.6 screws (1.6 mm diameter, 0.35 mm thread pitch). It weighs approximately 0.35 oz (10 g). Versions with the extended motor shaft have a 1mm diameter round shaft that protrudes 4.5 mm from the rear of the motor, between the two motor terminals; this is not pictured in the above dimension diagram.

Note: The gearbox on the 1000:1 and 1000:1 HP micro metal gearmotors is 12.5 mm long. All of the other micro metal gearmotors have 9mm-long gearboxes, as shown in the above dimension diagram.

Motor Accessories

• Wheels and Hubs: The micro metal gearmotor’s output shaft matches our assortment of Pololu wheels and the Solarbotics RW2 rubber wheel. You can also use the Pololu universal mounting hub to mount custom wheels and mechanism to the micro metal gearmotor’s output shaft.

Pololu wheel 32×7mm on a micro metal gearmotor.

Pololu wheel 42×19mm with micro metal gearmotor.

A pair of Pololu universal aluminum mounting hubs for 3 mm shaft.

Black Pololu 70×8mm wheel on a Pololu micro metal gearmotor.

Black Pololu 90×10mm wheel on a Pololu micro metal gearmotor.

Pololu 30T track set with drive sprocket mounted on a micro metal gearmotor to the left; idler sprocket is on the right.

• Mounting Brackets: Our mounting bracket (also available in white) and extended mounting bracket are specifically designed to securely mount the gearmotor while enclosing the exposed gears. We recommend the extended mounting bracket for wheels with recessed hubs, such as the Pololu wheel 42×19mm.

Black micro metal gearmotor mounting bracket pair with included screws and nuts.

White micro metal gearmotor mounting bracket pair with included screws and nuts.

Pololu micro metal gearmotor bracket extended with micro metal gearmotor.

• Quadrature Encoder: We offer a quadrature encoder for this motor that works with our extended bracket and 42×19mm wheel and provides feedback about wheel rotation (direction and speed). The encoder can be purchased as an individual unit or as part of an encoder set that includes two encoders, a pair of extended brackets, and a pair of 42×19mm wheels—just pick the particular micro metal gearmotor that best suits your application and you have a solution for closed-loop motor control.

Encoder for Pololu wheel 42×19mm with wheel, motor, and bracket.

Side view of the encoder for Pololu wheel 42×19mm, mounted to a bracket.

Oscilloscope capture of encoder outputs with the wheel spinning at 630 RPM.

• Motor Controllers: We have a number of motor controllers that make it easy to drive these micro metal gearmotors, including our qik 2s9v1 dual serial motor controller and our programmable Baby Orangutan and Orangutan SVP robot controllers. The inexpensive qik 2s9v1 allows variable speed and direction control of two small, brushed DC motors using a simple serial interface; the Orangutans combine a programmable Atmel AVR microcontroller and dual motor driver all in a single package and make interfacing with the motor drivers simple when you use our Pololu AVR library. All of the above controllers use the TB6612FNG dual motor driver, for which we also offer a simple carrier board.

Pololu qik 2s9v1 dual serial motor controller.

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

TB6612FNG dual motor driver carrier.

Selecting the Right Gearmotor

We offer a wide selection of metal gearmotors that offer different combinations of speed and torque. Our metal gearmotor comparison table can help you find the motor that best meets your project’s requirements.

Some of the Pololu metal gearmotors.

People often buy this product together with:

Pololu Micro Metal Gearmotor Bracket Extended Pair

Pololu Micro Metal Gearmotor Bracket Pair - Black

Pololu Wheel 42x19mm Pair