1.  Field of the Invention
The present invention relates generally to a pneumatic tool, and more particularly to an innovative one which is designed with a cylinder dividing mechanism. 
2.  Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
The drive system of a pneumatic tool is structurally designed in a way that air pressure is guided into a cylinder to drive the rotation of a vane rotor synchronously with a shaft lever for generating preset actions (e.g.: loosening or locking the bolts). 
Generally, a common bias vane is assembled into the cylinder, then a lateral space with larger spacing between the vane and cylinder is taken as a driving space for guiding, compression, expansion and relief of air pressure.  Yet, after air pressure is guided into the driving space, a relief port must be set at almost half of the stroke for smooth, continuous rotation of the vane, but the compression stroke of air pressure will be limited, making it difficult to further increase the torsion.  Given the fact that the driving torsion of the pneumatic tool depends on the driving force for the vane, it is understood that, if the volume of the cylinder is not increased, the efficient stroke of the vane under air pressure is restricted by the position of the relief port, making it impossible to further increase the stroke and driving torsion (incl.:  clockwise and counterclockwise rotation) of the pneumatic tool as a bottleneck in this industry. 
Thus, to overcome the aforementioned problems of the prior art, it would be an advancement if the art to provide an improved structure that can significantly improve the efficacy. 
Therefore, the inventor has provided the present invention of practicability after deliberate design and evaluation based on years of experience in the production, development and design of related products.