75:1 Metal Gearmotor 25Dx69L mm HP 12V with 48 CPR Encoder
This gearmotor consists of a high-power, 12V brushed DC motor combined with a 74.83:1 metal spur gearbox, and it has an integrated 48CPR 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 25mm, and the D-shaped output shaft is 4mm in diameter and extends 12.5mm from the face plate of the gearbox. This gearmotor is also available without an encoder.
Key specifications:
| voltage | no-load performance | stall extrapolation |
|---|---|---|
| 12 V | 130 RPM, 300 mA | 17 kg⋅cm (240 oz⋅in), 5.6 A |
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 25mm diameter case and 4mm 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 48CPR 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.
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 200oz-in (15kg-cm); we strongly advise keeping applied loads well under this limit. Stalls can also result in rapid (potentially on the order of a second) 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.
Details for item #4846
Exact gear ratio:
Warning: Do not screw too far into the mounting holes as the screws can hit the gears. We recommend screwing no further than 2mm (0.08″) into the screw hole.
Using the encoder (if applicable)
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, 8″ (20cm) 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 (3.5V to 20V) |
| Yellow | encoder A output |
| White | encoder B output |
The Hall sensor requires an input voltage, Vcc, between 3.5 and 20V and draws a maximum of 10mA. The A and B outputs are square waves from 0V 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.
Dimensions
| Size: | 25D x 69L mm1 |
|---|---|
| Weight: | 104 g |
| Shaft diameter: | 4 mm |
General specifications
| Gear ratio: | 74.83:1 |
|---|---|
| No-load speed @ 12V: | 130 rpm |
| No-load current @ 12V: | 300 mA |
| Stall current @ 12V: | 5600 mA |
| Stall torque @ 12V: | 240 oz·in2 |
| No-load speed @ 6V: | 65 rpm3 |
| Stall current @ 6V: | 2800 mA3 |
| Stall torque @ 6V: | 120 oz·in3 |
| Lead length: | 8 in4 |
| Motor type: | 5.6A stall @ 12V (HP 12V) |
| Encoders?: | Y |
Notes:
- 1
- Length measurement is from gearbox face plate to back of encoder cap (it does not include the output shaft). See dimension diagram for details.
- 2
- This is a theoretical value; stalling the gearbox output shaft is likely to damage the gearbox.
- 3
- This motor will run at 6V but is intended for operation at 12V.
- 4
- May vary by a few inches.
File downloads
- Dimension diagram of Pololu 25D mm Metal Gearmotors (223k pdf)
- 3D models of 25D mm gearmotors (9MB zip)
- This file contains 3D models (in the step file format) of the 25Dmm gearmotors with and without encoders.
- Modifying the Wild Thumper to use motors with encoders (3MB pdf)
- Customer Richard Nguyen has documented his work modifying the Wild Thumper chassis to use 25D motors with encoders in place of the chassis’s included motors.
Recommended links
-
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.