DSServo AS3103PG 360-Degree Continuous Rotation Servo

A standard servo is mechanically limited to roughly 180 degrees of rotation with position feedback, but this one is built specifically to spin continuously in either direction like a small geared DC motor - while still accepting the same familiar PWM control signal a standard servo uses. That combination (continuous rotation, servo-style control) is exactly what a wheeled robot's drive motor needs: simple PWM speed and direction control without a separate motor driver circuit.

Dual ball bearing construction (rather than plain bushings) reduces friction and extends service life under continuous spinning duty, a genuinely different wear profile than a positional servo sees since this one is expected to run continuously rather than holding a fixed angle. Torque of 5kg-cm at 4.8V (rising to 5.5kg-cm at 6V) gives real drive power for a small-to-medium robot chassis, and plastic gearing keeps cost down for a component that's often used in pairs or more per robot.

Common uses are wheeled robot drive motors controlled directly from a standard servo-output pin without a separate motor driver, smart car and educational robotics kits, and any mechanism needing continuous rotation with simple PWM speed/direction control rather than positional servo behavior.