Torsion-detecting pneumatic impact tool

A torsion-detecting pneumatic impact tool, including:

• a main body, a rotating assembly and a hammering set disposed inside the main body, the hammering set having at least one hammering block and a rotating portion which is connected with each hammering block, each hammering block, the rotating portion and the rotating assembly rotating synchronously;
• a transmission shaft, penetrating through each hammering block, the transmission shaft actuated intermittently by the hammering block's swing strike;
• a torsion detecting unit, including a marking piece which has a plurality of blocks, at least two sensors which detect the marking piece and a processing unit which is electrically connected with each sensor, the marking piece and the rotating assembly rotating synchronously;
• wherein, when each hammering block swing strikes the transmission shaft in a direction, each hammering block, the rotating portion and the marking piece slightly rotate reversely because of a counterforce of swing strike, wherein when the marking piece rotates reversely, the processing unit receives a signal of a degree of rotation of the blocks detected by the at least two sensors and computes a torsion value.