Duty cycle limits are normally designed to prevent a motor from overheating. Not sure why exceeding them would cause a breaker to trip. Unless, of course, the motor overheated to the point where the insulation burned off the coils and caused a short. But then it presumably wouldn't have worked on the ground.
A mechanical jam that stalled the motor might cause an overload and trip the breaker, but that wouldn't be directly related to duty cycle.