US Patent 7921933 Impact driving tool

In a driving tool, a diameter of an intermediate member is enlarged to increase a mass of the intermediate member and an outside diameter of a cylinder at a position where the intermediate member is internally provided is enlarged in accordance with the enlarged diameter of the intermediate member. Further, in the driving tool, a bearing thickness of a ball bearing is reduced correspondingly to a dimension of the enlarged outside diameter of the cylinder and a washer is provided at a part where the ball bearing abuts on the cylinder in the forward and backward moving direction thereof.