Patent ID: 7032685

Claim:
A fastening tool having a rotatively hitting mechanism, comprising: a generally cylindrically shaped liner filled with oil and connecting rotatively to a drive mechanism; a projection portion disposed on an inner wall surface of said liner; an anvil shaft disposed rotatively and coaxially within said liner; a cylindrical bore disposed within said anvil shaft and crossing a rotary axis of said anvil shaft; a piston slidably engaged within said cylinder; an oil passage connecting said inside of said cylinder with an outside of said anvil shaft; and a rolling member disposed at a top end of said piston so as to roll along an inner wall surface of said liner; elastic means for pressing said rolling member against said inner wall surface of said liner; and said rolling member pressing against both of said projection portion and said piston thereby raising pressure in said anvil cylindrical bore and defining a high pressure chamber disposed entirely in said anvil.