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Portable percussive machine

  • US 5,097,913 A
  • Filed: 10/26/1990
  • Issued: 03/24/1992
  • Est. Priority Date: 10/28/1989
  • Status: Expired due to Term
First Claim
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1. A percussive machine comprising a housing having a cylinder including a bottom end housed therein, a drive piston reciprocally movable within said cylinder for repeatedly driving a hammer piston towards said bottom end via a gas cushion in a working chamber defined in said cylinder between said drive piston and said hammer piston, said hammer piston impacting against a neck of a tool carried by said housing at said bottom end, said hammer piston being displaced towards said bottom end of said cylinder past ports defined in a wall of said cylinder through which said gas cushion in said working chamber is relieved to inactivate said hammer piston when said tool is displaced away from said bottom end to a position out of the reach of said hammer piston, said machine further including a braking chamber defined in said cylinder between said ports and said bottom end of said cylinder for pneumatically braking said displacement of said hammer piston, and means in said housing for resiliently supporting said bottom end of said cylinder to allow displacement of said bottom end relative to said cylinder in response to pneumatic pressure generated by said hammer piston in said braking chamber during said displacement of said hammer piston into said braking chamber.

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