Buffer system for fastener driving devices

Claim 1

A buffer system for fastener driving devices having a driving piston guided in a driving cylinder and operated by air under pressure, comprising a first buffer element (16) having a radially inner portion resting on a bottom surface (20) of said driving cylinder (2), a second buffer element (22) arranged for cooperation with said first buffer element for performing a damping function, said first and second buffer elements being made of materials having different hardnesses such that the first buffer element is made of a hard elastic material while the second buffer element is made of a relatively soft elastic material, said first buffer element (16) further having a radially intermediate portion including a surface area (18) normally spaced from said bottom surface of said driving cylinder for normally providing a spacing (19) between said surface area (18) of said first buffer element (16) and said bottom surface of the driving cylinder, at least a part of said intermediate portion of said surface area of said first buffer element being arranged to be movable relative to said bottom surface of said driving cylinder, said first buffer element further having a radially outer portion (21) resting with a radially outwardly directed bias force against an inner surface of said driving cylinder above said bottom surface to provide for said spacing, wherein said first buffer element (16) performs its damping function in two phases, so that, in response to an impact by said driving piston on said second buffer element (22), the first buffer element first causes energy dissipation by friction between said radially outer portion (21) and said inner surface of said driving cylinder until said spacing (19) disappears whereupon the first buffer element causes further energy dissipation as a result of its inner deformation.