Abstract: A hydraulic hinge, which can close automatically a door and firmly hold the door at a certain open position without any conventional door closer or door checking device, comprises a casing, a seat having a hexagonal opening therein, a buffer hydraulic mechanism and a spiral reversing spring installed in the casing, and a piston mounted on the buffer hydraulic mechanism and having a hexagonal piston stem extending through the spiral reversing spring to move reciprocatively within the hexagonal opening of the seat.

Abstract: An automatic door closer in which a piston operatively connected to the door to be moved in axial direction during turning of the door in either direction from a closed to an open position divides the fluid filled housing of the door closer into two pressure compartments which are connected by two channels in which adjustable throttles are arranged to dampen the movement of the door or to be completely closed to prevent passage of fluid through the channels to hold the door in any open position.

Abstract: Disclosed herein is a device for closing swinging doors which is mounted in a door frame and has an elongated housing with a spindle rotatably mounted in one end thereof by which the door closer is secured to a door. A cylinder is interiorly formed in the other end of the housing and has a piston disposed therein. The piston rod extends from the cylinder and is secured at its extended end to a pair of flat carrier plates which are slidably mounted within the housing about the spindle and biased to maintain the door in a closed position. Camming surfaces are carried by the spindle which cooperate with a pair of cam followers carried by the carrier plates to hold the door in an open position. Valve means communicating with the cylinder are provided to permit fluid flow from one end of the cylinder to the other about the piston for controlling the rate of travel of the piston within the cylinder and thereby regulate the rate of movement of the door as it is being opened, closed and latched.