This compact, inexpensive, low-current gearmotor (brushed DC motor with a 120:1 reduction gearbox) is well suited for use in small robots. At 4.5 V, it has a free-run speed of 120 RPM and a stall torque of approximately 20 oz-in (however, the built-in safety clutch might start slipping before the stall torque is reached). The D-shaped output shaft has a diameter of 3 mm and works with the Pololu wheels and 3mm universal aluminum mounting hub. This gearbox output shaft is offset from but parallel to the motor shaft.
Compare all products in Pololu Plastic Gearmotors or 3mm Shaft Gearmotors.