Speed reducer, detection system and detection method

The invention provides a speed reducer, a detection system and a detection method; the output end of the speed reducer is connected with a paddle shaft, the speed reducer comprises a machine body; an actuating part used for offering negative pull force to the paddle shaft, the actuating part is arranged in the machine body, and one end of the actuating part is connected with the paddle shaft in a drive mode. The speed reducer is offered and the actuating part is used for offering the action force to the paddle shaft while having test to the engine on the ground, and the negative pull force generated by the paddle shaft in the actual running operation is imitated, when the negative pull force reaches the preset value of the negative pull force automatic feathering system of the speed reducer, the negative pull force automatic feathering system is detected whether to work normally after mounted according to the concrete work state of the negative pull force automatic feathering system and the potential safety hazard caused by that the mounted feathering system cannot be detected of prior art is also avoided.