9.7:1 Metal Gearmotor 25Dx48L mm HP 6V with 48 CPR Encoder

9.7:1 Metal Gearmotor 25Dx48L mm HP 6V with 48 CPR Encoder
Pololu item #: 2271 10 in stock

Price break Unit price (US$)
1 36.95
10 33.26

backorders allowed

This gearmotor consists of a high-power, 6 V brushed DC motor combined with a 9.68:1 metal spur gearbox, and it has an integrated 48 CPR quadrature encoder on the motor shaft, which provides 464.64 counts per revolution of the gearbox’s output shaft. The gearmotor is cylindrical, with a diameter just under 25 mm, and the D-shaped output shaft is 4 mm in diameter and extends 12.5 mm from the face plate of the gearbox.

Key specs at 6 V: 1000 RPM and 450 mA free-run, 17 oz-in (1.2 kg-cm) and 6.5 A stall.

You can use the following selection boxes to see all of our 25D metal gearmotor versions with integrated encoders:

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We also have versions without encoders:

Select options:
 Description Specs (10) Pictures (7) Resources (1) FAQs (2) On the blog (0) 


These cylindrical brushed DC gearmotors are available in a wide range of gear ratios and with five different motors (two power levels of 6V motors and three power levels of 12V motors). The gearmotors all have the same 25 mm diameter case and 4 mm diameter gearbox output shaft, so it is generally easy to swap one version for another if your design requirements change (though the length of the gearbox tends to increase with the gear ratio). Some versions are also available with an integrated 48 CPR quadrature encoder on the motor shaft. Please see the 25D metal gearmotor comparison table for detailed specifications of all our 25D 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:

Motor Type Stall
@ Rated Voltage
@ Rated Voltage
Stall Torque
@ Rated Voltage

With Encoder

Without Encoder
6 V high-power
6.5 A 9800 RPM 2 oz-in 1:1 HP 6V w/encoder
2200 RPM 8 oz-in 4.4:1 HP 6V w/encoder 4.4:1 HP 6V
1000 RPM 17 oz-in 9.7:1 HP 6V w/encoder 9.7:1 HP 6V
480 RPM 36 oz-in 20.4:1 HP 6V
285 RPM 60 oz-in 34:1 HP 6V w/encoder 34:1 HP 6V
210 RPM 80 oz-in 47:1 HP 6V w/encoder 47:1 HP 6V
130 RPM 130 oz-in 75:1 HP 6V w/encoder 75:1 HP 6V
100 RPM 160 oz-in 99:1 HP 6V w/encoder 99:1 HP 6V
57 RPM 260 oz-in 172:1 HP 6V
6 V low-power
2.4 A 6100 RPM 1 oz-in 1:1 LP 6V w/encoder
1400 RPM 5 oz-in 4.4:1 LP 6V
630 RPM 11 oz-in 9.7:1 LP 6V w/encoder 9.7:1 LP 6V
300 RPM 24 oz-in 20.4:1 LP 6V
180 RPM 40 oz-in 34:1 LP 6V w/encoder 34:1 LP 6V
130 RPM 50 oz-in 47:1 LP 6V w/encoder 47:1 LP 6V
82 RPM 85 oz-in 75:1 LP 6V w/encoder 75:1 LP 6V
62 RPM 110 oz-in 99:1 LP 6V
36 RPM 170 oz-in 172:1 LP 6V w/encoder 172:1 LP 6V
27 RPM 220 oz-in 227:1 LP 6V
16 RPM 250 oz-in 378:1 LP 6V
12 RPM 300 oz-in 499:1 LP 6V
12 V high-power
5.5 A 2200 RPM 23 oz-in 4.4:1 HP 12V
1000 RPM 44 oz-in 9.7:1 HP 12V
480 RPM 85 oz-in 20.4:1 HP 12V
285 RPM 120 oz-in 34:1 HP 12V
210 RPM 165 oz-in 47:1 HP 12V
130 RPM 240 oz-in 75:1 HP 12V
100 RPM 300 oz-in 99:1 HP 12V
12 V medium-power
2.1 A 1750 RPM 11 oz-in 4.4:1 MP 12V
800 RPM 22 oz-in 9.7:1 MP 12V
375 RPM 42 oz-in 20.4:1 MP 12V
225 RPM 63 oz-in 34:1 MP 12V
165 RPM 85 oz-in 47:1 MP 12V
100 RPM 125 oz-in 75:1 MP 12V
77 RPM 165 oz-in 99:1 MP 12V
45 RPM 250 oz-in 172:1 MP 12V
34 RPM 320 oz-in 227:1 MP 12V
12 V low-power
1.1 A 1250 RPM 8 oz-in 4.4:1 LP 12V
570 RPM 15 oz-in 9.7:1 LP 12V
270 RPM 29 oz-in 20.4:1 LP 12V
160 RPM 43 oz-in 34:1 LP 12V
115 RPM 60 oz-in 47:1 LP 12V
75 RPM 85 oz-in 75:1 LP 12V
55 RPM 115 oz-in 99:1 LP 12V
32 RPM 180 oz-in 172:1 LP 12V
24 RPM 240 oz-in 227:1 LP 12V
15 RPM 320 oz-in 378:1 LP 12V

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 200 oz-in (15 kg-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, especially for the versions that use high-power (HP) motors; a general recommendation for brushed DC motor operation is 25% or less of the stall current.

In general, these kinds of motors can run at voltages above and below their nominal voltages; lower voltages might not be practical, and higher voltages could start negatively affecting the life of the motor.

Details for item #2271

Exact gear ratio: ``(22×22×24) / (12×10×10) =bb(9.68:1)``

Gearmotor accessories

The face plate has two mounting holes threaded for M3 screws. You can use our custom-designed 25D mm metal gearmotor bracket (shown in the picture below) to mount the gearmotor to your project via these mounting holes and the screws that come with the bracket.

Pololu 25D mm metal gearmotor bracket pair.
Pololu 25D mm gearmotor with bracket.

The 4 mm diameter gearbox output shaft works with Pololu universal aluminum mounting hub for 4mm shafts, which can be used to mount our larger Pololu wheels (60mm-, 70mm-, 80mm-, and 90mm-diameter) or custom wheels and mechanisms to the gearmotor’s output shaft as shown in the left picture below. Alternatively, you could use our 4mm scooter wheel adapter to mount many common scooter, skateboard, and inline skate wheels to the gearmotor’s output shaft as shown in the right picture below.

25D mm metal gear motor with 48 CPR encoder and Pololu 60×8mm wheel.
A 25D mm gearmotor connected to a scooter wheel by the 4 mm scooter wheel adapter.

These are the same type of motors used in the Wild Thumper all-terrain chassis, so the gearbox’s output shaft also works directly with the hex adapters included with the 120mm-diameter Wild Thumper wheels (the left picture below shows a 25D mm gearmotor while the right picture shows the smaller 20D mm gearmotor):

Dagu Wild Thumper wheel 120×60mm (chrome) with Pololu 25D mm metal gearmotor.
Dagu Wild Thumper wheel 120×60mm (metallic red) with Pololu 20D mm metal gearmotor.
For a general-purpose hex adapter, consider our 12mm hex wheel adapter, which lets you use this motor with many common hobby RC wheels.

12mm Hex Wheel Adapter for 4mm Shaft on a 20D mm Metal Gearmotor.


The diagram below shows the dimensions (in mm) of the 25D mm line of gearmotors. Note that the encoder PCB and magnetic disc are not shown in this dimension diagram; the encoder assembly extends an additional 12 mm beyond the rear of the motor. The value of L is shown in the table below.

Dimension diagram (in mm) for the 25D mm metal gearmotors.

Gear Ratio L (mm)
20.4:1 19

25D mm metal gearmotor with 48 CPR encoder: close-up view of encoder.

Using the Encoder

A two-channel Hall effect encoder is used to sense the rotation of a magnetic disk on a rear protrusion of the motor shaft. The quadrature encoder provides a resolution of 48 counts per revolution of the motor shaft when counting both edges of both channels. To compute the counts per revolution of the gearbox output, multiply the gear ratio by 48. The motor/encoder has six color-coded, 11" (28 cm) leads terminated by a 1×6 female header with a 0.1″ pitch, as shown in the main product picture. This header works with standard 0.1″ male headers and our male jumper and precrimped wires. If this header is not convenient for your application, you can pull the crimped wires out of the header or cut the header off. The following table describes the wire functions:

Color Function
Red motor power (connects to one motor terminal)
Black motor power (connects to the other motor terminal)
Green encoder GND
Blue encoder Vcc (3.5 – 20 V)
Yellow encoder A output
White encoder B output

The Hall sensor requires an input voltage, Vcc, between 3.5 and 20 V and draws a maximum of 10 mA. The A and B outputs are square waves from 0 V to Vcc approximately 90° out of phase. The frequency of the transitions tells you the speed of the motor, and the order of the transitions tells you the direction. The following oscilloscope capture shows the A and B (yellow and white) encoder outputs using a motor voltage of 6 V and a Hall sensor Vcc of 5 V:

Encoder A and B outputs for 25D mm HP metal gearmotor with 48 CPR encoder (motor running at 6 V).

By counting both the rising and falling edges of both the A and B outputs, it is possible to get 48 counts per revolution of the motor shaft. Using just a single edge of one channel results in 12 counts per revolution of the motor shaft, so the frequency of the A output in the above oscilloscope capture is 12 times the motor rotation frequency.

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 Universal Aluminum Mounting Hub for 4mm Shaft, #4-40 Holes (2-Pack) Pololu Universal Aluminum Mounting Hub for 4mm Shaft, #4-40 Holes (2-Pack)
VNH5019 Motor Driver Carrier VNH5019 Motor Driver Carrier
Machine Screw: #4-40, 1/2" Length, Phillips (25-pack) Machine Screw: #4-40, 1/2" Length, Phillips (25-pack)

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Related Categories

6V High-Power (HP) 25D mm Gearmotors
Pololu Wheels and Tracks
RoboClaw Motor Controllers
Brushed DC Motor Controllers
Brushed DC Motor Drivers
Robot Controllers
Current Sensors
37D mm Gearmotors
Micro Metal Gearmotors
Wild Thumper All-Terrain Chassis
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