This gearmotor consists of a high-power, 12 V brushed DC motor combined with a 74.83:1 metal spur gearbox, and it has an integrated 48 CPR quadrature encoder on the motor shaft, which provides 3591.84 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.
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). All 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:
@ Rated Voltage
@ Rated Voltage
@ Rated Voltage
|6.5 A||10,000 RPM||5 oz-in||1:1 HP 6V w/encoder|
|2150 RPM||20 oz-in||4.4:1 HP 6V w/encoder||4.4:1 HP 6V|
|990 RPM||39 oz-in||9.7:1 HP 6V w/encoder||9.7:1 HP 6V|
|460 RPM||75 oz-in||20.4:1 HP 6V w/encoder||20.4:1 HP 6V|
|280 RPM||90 oz-in||34:1 HP 6V w/encoder||34:1 HP 6V|
|200 RPM||115 oz-in||47:1 HP 6V w/encoder||47:1 HP 6V|
|130 RPM||150 oz-in||75:1 HP 6V w/encoder||75:1 HP 6V|
|97 RPM||210 oz-in||99:1 HP 6V w/encoder||99:1 HP 6V|
|56 RPM||350 oz-in||172:1 HP 6V w/encoder||172:1 HP 6V|
|2.4 A||6200 RPM||2 oz-in||1:1 LP 6V w/encoder|
|1300 RPM||8 oz-in||4.4:1 LP 6V w/encoder||4.4:1 LP 6V|
|590 RPM||17 oz-in||9.7:1 LP 6V w/encoder||9.7:1 LP 6V|
|290 RPM||33 oz-in||20.4:1 LP 6V w/encoder||20.4:1 LP 6V|
|170 RPM||50 oz-in||34:1 LP 6V w/encoder||34:1 LP 6V|
|120 RPM||65 oz-in||47:1 LP 6V w/encoder||47:1 LP 6V|
|78 RPM||95 oz-in||75:1 LP 6V w/encoder||75:1 LP 6V|
|58 RPM||130 oz-in||99:1 LP 6V w/encoder||99:1 LP 6V|
|34 RPM||200 oz-in||172:1 LP 6V w/encoder||172:1 LP 6V|
|25 RPM||220 oz-in||227:1 LP 6V w/encoder||227:1 LP 6V|
|15 RPM||300 oz-in||378:1 LP 6V w/encoder||378:1 LP 6V|
|11 RPM||400 oz-in||499:1 LP 6V w/encoder||499:1 LP 6V|
|5.6 A||10,200 RPM||5.5 oz-in||1:1 HP 12V w/encoder|
|2250 RPM||23 oz-in||4.4:1 HP 12V w/encoder||4.4:1 HP 12V|
|1030 RPM||44 oz-in||9.7:1 HP 12V w/encoder||9.7:1 HP 12V|
|500 RPM||85 oz-in||20.4:1 HP 12V w/encoder||20.4:1 HP 12V|
|290 RPM||120 oz-in||34:1 HP 12V w/encoder||34:1 HP 12V|
|210 RPM||165 oz-in||47:1 HP 12V w/encoder||47:1 HP 12V|
|130 RPM||240 oz-in||75:1 HP 12V w/encoder||75:1 HP 12V|
|100 RPM||300 oz-in||99:1 HP 12V w/encoder||99:1 HP 12V|
|2.1 A||7800 RPM||2.7 oz-in||1:1 MP 12V w/encoder|
|1700 RPM||11 oz-in||4.4:1 MP 12V w/encoder||4.4:1 MP 12V|
|770 RPM||22 oz-in||9.7:1 MP 12V w/encoder||9.7:1 MP 12V|
|370 RPM||42 oz-in||20.4:1 MP 12V w/encoder||20.4:1 MP 12V|
|220 RPM||63 oz-in||34:1 MP 12V w/encoder||34:1 MP 12V|
|160 RPM||85 oz-in||47:1 MP 12V w/encoder||47:1 MP 12V|
|100 RPM||125 oz-in||75:1 MP 12V w/encoder||75:1 MP 12V|
|76 RPM||165 oz-in||99:1 MP 12V w/encoder||99:1 MP 12V|
|43 RPM||250 oz-in||172:1 MP 12V w/encoder||172:1 MP 12V|
|33 RPM||320 oz-in||227:1 MP 12V w/encoder||227:1 MP 12V|
|1.1 A||5600 RPM||2 oz-in||1:1 LP 12V w/encoder|
|1200 RPM||8 oz-in||4.4:1 LP 12V w/encoder||4.4:1 LP 12V|
|560 RPM||15 oz-in||9.7:1 LP 12V w/encoder||9.7:1 LP 12V|
|260 RPM||29 oz-in||20.4:1 LP 12V w/encoder||20.4:1 LP 12V|
|150 RPM||43 oz-in||34:1 LP 12V w/encoder||34:1 LP 12V|
|110 RPM||60 oz-in||47:1 LP 12V w/encoder||47:1 LP 12V|
|71 RPM||85 oz-in||75:1 LP 12V w/encoder||75:1 LP 12V|
|55 RPM||115 oz-in||99:1 LP 12V w/encoder||99:1 LP 12V|
|31 RPM||180 oz-in||172:1 LP 12V w/encoder||172:1 LP 12V|
|23 RPM||240 oz-in||227:1 LP 12V w/encoder||227:1 LP 12V|
|14 RPM||320 oz-in||378:1 LP 12V w/encoder||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); . 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.
Exact gear ratio: 22×20×22×22×22×2312×12×10×10×10×10≈74.83:1
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.
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.
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):
For a general-purpose hex adapter, consider our 12mm hex wheel adapter, which lets you use this motor with many common hobby RC wheels.
The diagram below shows the dimensions of the 25D mm line of gearmotors (units are mm over [inches]). This diagram is also available as a downloadable PDF (223k pdf).
The versions of these gearmotors with encoders use a A two-channel Hall effect sensor to detect 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 standard0.1″ 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:
|Red||motor power (connects to one motor terminal)|
|Black||motor power (connects to the other motor terminal)|
|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 6V 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.
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.