Patents by Inventor Sidney Lieberman

Sidney Lieberman has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Door closer assist linkage
    Patent number: 4419787
    Abstract: A control linkage for use with a door closer, wherein the linkage is provided with a spring which resiliently biases against relative rotation of a pair of arms as the arms approach a door-open limit position, and which aids the door closer in moving the door from the door-open limit position.
    Type: Grant
    Filed: September 23, 1982
    Date of Patent: December 13, 1983
    Assignee: Dorma Door Controls Inc.
    Inventor: Sidney Lieberman
  • Hydraulic door closer construction
    Patent number: 4394787
    Abstract: A hydraulic door closer is provided with a fluid seal for its output shaft, the seal comprising multiple O-rings disposed side-by-side in an elongated annular chamber.
    Type: Grant
    Filed: July 27, 1978
    Date of Patent: July 26, 1983
    Assignee: Dorma Door Controls Inc.
    Inventor: Sidney Lieberman
  • Piston assembly for door closer
    Patent number: 4019220
    Abstract: Hydraulic door closer apparatus comprises a cylinder and an elongated piston disposed in the cylinder, the piston being made of relatively easily machined material, but having associated with it a rack of harder, wear and impact-resistant material for transmitting forces and motion to and from the piston.
    Type: Grant
    Filed: January 13, 1976
    Date of Patent: April 26, 1977
    Assignee: Reading Door Closer Corporation
    Inventor: Sidney Lieberman