Abstract: A door closer power adjusting device for a door closer having a spindle driven by a compressed spring with a movable plate for adjusting spring compression, or with a screw for adjusting spring compression, between a high and low level of compression. A powered unit moves the plate in a first direction to achieve the low level of compression and in a second direction to achieve the high level of compression. A switch activates the powered unit in the first direction and a first switch is engaged when the spring is compressed to the low level of compression to deactivate the powered unit. A timing circuit activates the powered unit in a second direction after passage of a predetermined time. A second switch is engaged when the spring is compressed to the high level of compression to deactivate the powered unit.

Abstract: A latch mechanism is provided for a door which includes a rotatable latch which is rotated into and held in an open position to allow the door to open, and is released from the open position only when a sensing mechanism provided as a part of the latch mechanism, held in the door, senses the door frame upon a closing of the door. The latch is held in an over center engaged position which it is moved into due to a lost motion connection among some, but not all, elements of the latch mechanism.

Abstract: Clutch handle apparatus for opening doors and the like includes a torque limiting clutch subassembly which selectively disengages the handle from a spindle to prevent damage. The clutch subassembly includes a slip clutch removably coupled to a spindle pin allowing corotation of the handle and the spindle below the application of a predetermined torque, and free rotation of the handle with respect to the spindle by uncoupling the pin and the slip clutch at and above the application of a predetermined of torque to the handle.

Abstract: A hydraulic backcheck valve system for controlling an opening cycle of a door closer has a housing with an interior chamber, at least one cylinder, and a piston that can reciprocate between a door closing stroke and a door opening stroke within the cylinder. One side of the piston faces a variable volume chamber in the cylinder and an opposite side of the piston faces the interior chamber of the housing. The backcheck valve system has a fluid passage with a port in fluid communication with the cylinder and an opening in fluid communication with the interior chamber of the housing. The port is blocked by the piston during at least part of the door opening stroke. A one-way valve is disposed in fluid communication with the fluid passage and permits fluid to flow freely during a closing cycle of the door closer and prevents fluid flow from the second passage during the opening cycle. A backcheck valve is disposed in fluid communication with the passage and with the variable volume chamber.

Abstract: A blocking device for preventing a door closer from achieving a degree of rotation corresponding to a door hold-open position. A blocking device is provided which can be selectively protruded into a door closer housing to block the translation of a cam plate under influence of a rotating cam operatively connected to one of either the door or the door frame such that the 90.degree. or 105.degree. typical door hold open position cannot be achieved. The blocking device can be a rotatable limit bar which can be positioned to an interference or no-interference position, or it can be screw pins which can be threadingly inserted into the housing to block either the cam or other moving portions of the door closer such that the closer cannot achieve the door hold open position.

Abstract: A door closer having a spindle and cam arrangement for driving a cam plate longitudinally within a housing filled with oil, and dual rods connected to the cam plate at one end and to two pistons respectively at an opposite end. The pistons are reciprocal within cylinders having speed valves in flow communication to opposite sides of the pistons. Dual springs are arranged, one around each rod and compressed between the pistons and a fixed compression plate within the housing. A single adjusting screw extends from a front end of the housing to a threaded central aperture of the compression plate. Rotation of the adjusting screw sets the initial spring compression force of the return springs which influences the rate of closure of the door and the preload force of the door to the door frame.