Pneumatic ratchet wrench

A pneumatic ratchet wrench being connected with an air supply device and comprising:

• a housing extending along a first axis line and including an opening defined on one side of a front end thereof and an intake formed on a distal end thereof so as to couple with the air supply device;
• a ratchet head unit received in a front end of the housing and including a drive square extending along a second axis line perpendicular to the first axis line and extending out of the opening;
• an impact clutch unit received in the housing and coupled with the ratchet head unit;
• a driving unit disposed in a rear end of the housing and including a multi-chamber cylinder, a rotor member inserted into the multi-chamber cylinder and connecting with the impact clutch unit so as to drive the drive square to rotate, the multi-chamber cylinder having a body, a first chamber defined in the body, a second chamber formed in the body and communicating with the first chamber.