Pneumatic tool having clockwise and counterclockwise rotation function

A pneumatic tool comprising:

• a housing having an intake passage adapted to be connected with a compressed air source;
• an air cylinder disposed in said housing and including a cylinder wall centered at an X-axis and defining an air chamber, a valve seat centered at a Z-axis perpendicular to said X-axis and connected to said cylinder wall, a first passage, and a second passage, said first and second passages being formed in said cylinder wall and being in fluid communication with said air chamber and said valve seat;
• a valve unit including a rotary valve that is disposed in said valve seat and that has an intermediate passage, said rotary valve being rotatable about said Z-axis between a first position whereat said intermediate passage is in fluid communication with said first passage in said air cylinder, and a second position whereat said intermediate passage is in fluid communication with said second passage in said air cylinder;
• and
• a controlling unit including a movable pin disposed movably on said housing and operable to move in said housing along a Y-axis perpendicular to said X-axis and said Z-axis to thereby drive rotation of said rotary valve.