| 摘要 |
A door closer includes a tension member comprising spaced shafts acted by springs and connected to articulated chains which are coupled to an anchor plate secured to the door frame. Movement of the shafts is under the control of a uni-directionally operative fluid-filled damper having a piston carried by a piston rod which is connected to a cross head slidably mounted on the shafts and held against abutment washers by the springs. The damper serves to regulate the rate of movement of a door in the direction of closure without restricting significantly the rate of movement in the direction of opening. A fluid by-pass is provided in the damper by a rebate formed in the cylinder so that as the piston approaches the end of the cylinder over the final part of the closure movement the restraint imposed by the damper is relieved. The point in the closure movement at which the fluid by-pass becomes operative can be varied while the closer is installed so as to provide compensation for variations in the installation of the closer and variations of the gap between the door and its frame. In one embodiment this is achieved by securing the chains to an adjustment plate which is movable towards and away from the anchor plate. In another embodiment the piston rod is adjustable secured to the cross head, which in this case is in the form of a stirrup with a cross member on which the piston rod is carried presented towards and accessible from the outer end of the housing so as to enable the piston rod to be adjusted. |
