47:1 Metal Gearmotor 25Dx52L mm MP 12V with 48 CPR Encoder



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SKU: 1165 Category:


This gearmotor consists of a medium-power, 12 V brushed DC motor combined with a 46.85:1 metal spur gearbox, and it has an integrated 48 CPR quadrature encoder on the motor shaft, which provides 2248.86 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 12 V: 160 RPM and 200 mA free-run, 85 oz-in (6 kg-cm) and 2.1 A stall.

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); It is strongly advised to keep 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.

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.

Technical Specifications


Size: 25D x 64L mm
Weight: 101 g
Shaft diameter: 4 mm


Gear ratio: 46.85:1
No-load speed @ 12V: 160 rpm
No-load current @ 12V: 200 mA
Stall current @ 12V: 2100 mA
Stall torque @ 12V: 85 oz·in
No-load speed @ 6V: 80 rpm1
Stall current @ 6V: 1050 mA1
Stall torque @ 6V: 42 oz·in1
Lead length: 8 in2
Motor type: 2.1A stall @ 12V (MP 12V)
Encoders?: Y


1This motor will run at 6 V but is intended for operation at 12 V.
2May vary by a few inches.


Dimension diagram of Pololu 25D mm Metal Gearmotors (223k pdf)

Modifying the Wild Thumper to use motors with encoders (3MB pdf)

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.