Automower Wheel Motor.
Signs of a failed wheel motor include the robot mower turning in circles. when you turn the wheel manually you can hear a crunching sound.
581 62 13-06
Replaces part numbers
581 62 13-05
581 62 13-04
581 62 13-03
581 62 13-02
to fit 420,430x,435,440,450x,520,535,550.