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Fluid pressure motor

  • US 4,425,836 A
  • Filed: 02/20/1981
  • Issued: 01/17/1984
  • Est. Priority Date: 02/20/1981
  • Status: Expired due to Term
First Claim
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1. In a fluid pressure motor includinga cylinder having a bore and an end wall,a piston reciprocally movable within said cylinder and having a face opposing said end wall and an outer surface,a variable volume chamber defined within said bore between the end wall of said cylinder and the face of said piston, anda port in said cylinder for the transfer of said fluid to and from said chamber,the outer surface of said piston effectively closing said port during the terminal portion of movement of said piston in a direction toward the end wall of said cylinder,improvements therein for regulating the transfer of said fluid between said chamber and said port and for decelerating and cushioning said piston during said terminal portion of movement, said improvements comprising:

  • a channel formed into the outer surface of said piston for the transfer of said fluid from said chamber to said port, said channel forming a helix about said piston having a pitch such that at least a portion of said channel is in constant communication with said port during the terminal portion of movement of said piston.

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