US Patent 7165631 Pneumatic wrench having enhanced strength

A pneumatic wrench includes a pneumatic motor, a striking portion, and a drive shaft. The striking portion includes a support seat, a first hammer, and a second hammer. Thus, the first hammer and the second hammer are driven by the fixed pins and the movable pins of the support seat respectively, thereby preventing the fixed pins and the movable pins from being worn out or broken due to a stress concentration so as to increase the lifetime of the pneumatic wrench. In addition, the connecting rib is located between and connected to the first driven block and the second driven block of the drive shaft so as to enhance the structural strength of the drive shaft.