Abstract: A one way braking device has a first sealed chamber filled with a viscous fluid, a braking rotor being rotably supported within the chamber, a housing or the braking rotor, respectively, coacting with a pinion which in turn cooperates with a tooth rod or a gear or the like. The first housing is floatingly supported in a second chamber of a second housing. The circumference of the first housing and a locking portion of the wall of the second chamber are formed such that a positive interengagement between the first and second housings takes place if by a linear first force component the first housing and the locking portion are moved against each other. A free running between the first and second housings is effected when a second force component opposite to the first component effects between the first and second housings.

Abstract: A heart cam and damper unit includes a base member having fixed cylindrical portions and a stopper portion, a rotating member having a movable cylindrical portion which is rotatably assembled to the fixed cylindrical portion with a viscous fluid interposed between the movable cylindrical portion and the fixed cylindrical portions, and a pinion gear rotating integrally with the movable cylindrical portion, a heart cam member rotatable fitted around an outer periphery of an outwardly located one of the fixed cylindrical portion and the movable cylindrical portion, and a device interposed between the base member and the heart cam member and adapted to rotatably urge the heart cam member toward the stopper portion. The heart cam and damper unit is interposed between a main body portion and a movable portion which undergoes opening and closing action with respect to the main body portion and is constantly urged in an opening direction.

Abstract: A damper includes a housing having a cylindrical shape and filled with a viscous fluid, a first rotor rotatably received in the housing and having a first connecting portion formed at an end portion thereof, and a second rotor rotatably housed in the housing coaxially with the first rotor and having a second connecting portion formed at an end portion thereof. The first and second connecting portions engage to allow the first and second rotors together, and forms a space therebetween to allow the viscous fluid to pass therethrough. An elastic member urges the first connecting portion and the second connecting portion to connect together, and accumulates an elastic force in a state that the connection between the first and second connecting portions is released.

Abstract: A rotary damper includes a cylindrical member having walls on an inner peripheral surface of a cylindrical chamber along a radial line, and a rotor member having vanes moving along the inner peripheral surface of the cylindrical chamber. A resistance force of a viscous fluid filled in the cylindrical chamber is applied to the vanes when the cylindrical member rotates relative to the rotor member. The rotor member is formed of a thermoplastic resin containing inorganic filler or fiber. Thus, the rotor member having high strength can be obtained.

Abstract: A sliding resistance member (3) is interposed between a glove box (B) and a rod type air damper (21). It is assumed that when a glove box lid (L) corresponding to a open-close member starts opening, the rod type air damper (21) rotates while running idle in conjunction therewith, in a relation in which the rotary type oil damper (3) is positively interposed between the glove box (B) corresponding to the mounting shaft and the rod type air damper (21). However, since a braking force of the sliding resistance member (3) is applied to the side of the open-close member in a rotating section of the rod type air damper (21), an sufficient damper effect can be obtained even when the open-close member starts opening.

Abstract: A door closer comprises an actuator assembly (20) adapted for fitting within the thickness of a door and an anchor member (10) adapted for fitting in a door frame in opposed relation to said edge face of the door. An operating member (30) is driven by spring means (45) and coupled to said anchor member (10) to draw the door towards the door frame. An adjustable fluid-filled damper (50) is coupled to said operating member (30) and arranged to provide variable regulation the rate of movement of the operating member under the force of said spring means (45). Resilient thrust means (85) are arranged to exert an increased driving force of said operating member (30) and adjustable control means (100) are provided whereby said thrust means (85) is operative to augment the driving force to said operating member (30) over a defined but variable part of said range of movement corresponding to movement of the door over the final part of its movement into its closed position.

Abstract: A door closer assembly and method of making the assembly, in which the closing force is exerted by at least one closing spring. The door closer assembly comprises a housing, a rotor journalled in said housing to deliver torque, and at least one piston apparatus, wherein said housing, said rotor, and said at least one piston apparatus are comprised of the same material of construction and exhibit at least substantially the same thermal expansion coefficient.

Abstract: A door hold-open device including a track, a first catch slidably mounted for longitudinal movement in the track, a stop assembly including a second catch coupled to the track and adapted to engage the first catch wherein the second catch is moveable in a direction different than the longitudinal direction, a resilient member that applies a force to the second catch to urge the second catch into a position where the second catch engages the first catch when the first catch is adjacent to the second catch, and a linear actuator having a first position and a second position, wherein the linear actuator applies a first force to the resilient member in the first position and a second different force to the resilient member in the second position.

Abstract: The invention describes a door closer with an energy storage that includes a resisting spring (3), with a closer shaft (1) driven by the resisting spring (3) and with an hydraulic fluid damped damping device (12, 13), whereby the energy storage and the damping device (12, 13) act upon a common closer shaft (1), whereby the resisting spring (3) and the closer shaft (1) are not in contact with the fluid of the damping device (12, 13). In this way a particularly slim housing is possible.

Abstract: A damper for a pivot door has a piston movably received inside the damper and having a first channel and a second channel respectively and selectively communicating with a space full of hydraulic oil, such that the movement of the piston is able to be slowed by the interchange of the communication of the first channel and the space and the second channel and the space. Thus, the movement of the pivot door is slowed.

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: Door hinge with a locking device based on a field force, including a cylinder divided by a piston into working spaces that are filled with an operating medium whose viscosity can be changed by means of a field force. The working spaces are connected to one another by at least one flow connection that is subject to the influence of a field force generating element. The door hinge is designed as a pivot bearing, wherein the cylinder takes the form of a bearing eye and the piston takes the form of a rotary piston with at least one blade.

Abstract: A door closer and mounting bracket for attaching the door closer to either the door or the door frame. The door closer includes two pins at one end for engaging corresponding holes on the mounting bracket and the mounting bracket includes a resilient clip for engaging the body of the door closer.

Abstract: A control mechanism for use with a door closer, comprises a shaft (10), angularly movable between a normal position and a second position, the shaft (10) having a first portion (21a) and a second portion (21b), a brush spring (35) attached to the shaft first portion (21a) to return the shaft to its normal position, and a damping mechanism (36, 38) attached to the shaft second portion (21b) to resist shaft movement to its normal position. The damping mechanism includes a coiled strap-like member (36) keyed to the shaft and contained in a damping medium.

Abstract: A door closer and mounting bracket for attaching the door closer to either the door or the door frame. The door closer includes a lip at one end for engaging a corresponding hook on the mounting bracket and a screw passageway at the other end for engaging a screw on the mounting bracket. A unique mounting hole pattern is used to prevent installing the mounting bracket in the wrong orientation.

Abstract: A cylinder lock door closure device. In an exemplary application, the cylinder lock door closure device includes a cylindrical housing, a piston assembly, an arm assembly, a cylindrical catch piece and a hard stop whereby when a door is opened past 90° open, it will automatically lock in an open position. When the door is tapped toward the open position, the automatic lock will be released and the door returned to a closed position.

Abstract: A door closer unit (100) including a cylindrical housing (10) with a partition (14) axially extending inside and having a first liquid path; a moving body (20) with a movable barrier (24) dividing the interior of the housing into first and second chambers, and a rotational shaft (21) having an upper end extending upward; a door return spring (30) applying a recovering force to the door in a direction opposite to the direction when the moving body's rotational shaft (21) or housing (10) rotates in one direction; a high-viscosity liquid filling in the housing; a control check valve for opening a second liquid path when the door is opened, and closing the second liquid path when the door is closed; a cover (40) rotatably supporting the rotational shaft (21) of the moving body (20) and sealing the upper portion of the housing (10); a speed controller (19) regulating the amount of the liquid when the door is opened or closed, thus controlling the speed of the door; and a door stopper (29) for stopping the door whe

Abstract: A door closer and mounting bracket for attaching the door closer to either the door or the door frame. The door closer includes a lip at one end for engaging a corresponding hook on the mounting bracket and a screw passageway at the other end for engaging a screw on the mounting bracket. A unique mounting hole pattern is used to prevent installing the mounting bracket in the wrong orientation.

Abstract: A locating structure of an oil pressure door closer is composed of a locating plate, a main body of the door closer, and a plurality of fastening pins. The locating plate is fastened with a door and provided with a plurality of fastening holes. The main body is provided in one longitudinal side thereof with two longitudinal edges parallel to each other and forming therebetween a longitudinal space for accommodating the locating plate. The two longitudinal edges are provided with a plurality of through holes corresponding in location to the fastening holes of the locating plate. The fastening pins are received in the through holes and the fastening holes for fastening the main body with the locating plate.

Abstract: A control device for a door closer is arranged to control flow of pressure medium within a body part of the door closer and comprises an adjustment member supported by threads on the body part of the door closer, and in cooperation therewith, a separate substantially hollow control member, which is arranged to restrict the flow of the pressure medium when necessary. Turning of the adjustment member with respect to the body part of the door closer brings about movement of the control member in the axial direction of the control device for providing the desired control. The control member is arranged to be attached to the adjustment member in the radial direction so that movement of the control member with respect to the adjustment member in the axial direction is prevented.

Abstract: A door control device for use on a non-fire side of a fire-door mounted in a door frame in a fire-door safety installation has a door closer assembly filled with a hydraulic damping fluid and attached to a non-fire side of the fire-door by at least one fastener; a door control arm pivotally connected to the door frame at a first end and to the door closer assembly at a second end; and the hydraulic damping fluid is one of a group of fire resistant hydraulic fluids.

Abstract: A device for dampening the movement of a pivotally supported structural part, for example, a flap or closure within an automobile, comprises a pivot arm attached to the structural part, and a rack operatively connected to the pivot arm. A housing is rotatably supported upon a support surface or member, and a rotor is rotatably disposed within the housing along with a viscous fluid which tends to dampen rotary motion of the rotor. The rotor also comprises a pinion which is enmeshed with the rack, and the housing comprises a pair of guides for confining movement of the rack in a translational or rectilinear mode while maintaining the rack enmeshed with the rotor pinion. Consequently, when the flap or closure is either opened or closed, the flap or closure is moved in a dampened mode due to the movement of the pivot arm and the rack relative to the dampened rotor pinion.

Abstract: The present invention discloses door closers provided with automatic latching in any position along the stroke, and delayed action mechanism together with a mechanism to switch on and off the automatic latching and the delayed action operation modes. The function, on which the automatic latching and the delayed action functions are based, are described in detail and examples of embodiments in door closers provided with either automatic latching or delayed action or both are also described.

Abstract: A safety, fluid-actuated cylinder-and-piston mechanism for use with an article which is movable between first and second positions. The mechanism comprises a conventional, fluid-actuated cylinder-and-piston mechanism and an automatic locking bar. The piston rod of the cylinder-and-piston mechanism has one end attached to the movable article, and is movable between a fully retracted position in which the article is in its first position and a fully extended position in which the article is in its second position. The locking bar has a pivot end proximate the attachment between the piston rod and the movable article, and an opposite, nonpivot end. The locking bar is pivotable between a lowered and fully raised position and has a plurality of partially raised positions between its lowered and fully raised positions.

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.

Abstract: An improved multi-stage door closer for automatically closing a door after the door is opened, is disclosed. It contains a cylinder having three sections each with a different diameter, with the middle section having the largest diameter. A pair of speed adjusting mechanisms are provided which are sleeved about a piston rod placed inside the cylinder. Each of the speed adjusting mechanism contains a rotatable piston head, which will rotate with the cylinder, and a fixed piston head, which will not rotate with the cylinder. In a preferred embodiment, the rotatable piston head contains a radially extending groove in communication with an axially extending graded groove, and the fixed piston head contains a spiraled or serpentined O-ring that cuts across the axially extending graded groove.

Abstract: A hydraulic control system for automatically closing and opening a door is disclosed and has means for providing such opening and closing even if power is lost to the hydraulic control system. Further disclosed is a fluid control device of the hydraulic system which prevents the door from being opened or closed too quickly that might otherwise harm an individual that comes into the path of the moving door.

Abstract: A door stop including an hydraulic cylinder connectable to one of a door assembly part, a stop piston longitudinally displaceable in the hydraulic cylinder and connected with another part of the door assembly by a piston rod, and two spring-biased closing pistons located in two separate conduits formed in the stop piston for communicating two, spaced by the stop piston, pressure chambers formed in the cylinder, with a limited length conduit being formed in the hydraulic cylinder and by-passing the stop piston for directly communicating the pressure chambers.

Abstract: A mechanism for controlling the opening and closing of a closure object, comprising an outer cylinder whose inner chamber, contains hydraulic fluid, a distal end of the outer cylinder being attachable to either a closure object or an object to be closed. A circumferential single groove is located in an inner wall of the outer cylinder and a piston shaft telescopically received within the outer cylinder extends proximally therefrom, being attachable to either a closure object or an object to be closed, and distally into the inner chamber. A piston head is mounted distally on the piston shaft. The piston head contains a bore therethrough, a peripherally located circumferential retaining groove, and an inclined outer surface which increases in cross section in the distal direction. A seal prevents hydraulic fluid from passing around the piston head between the distal chamber and the proximal chamber. A snap ring, partially housed within the single groove, engages the inclined outer surface of the piston head.

Abstract: A multi-stage door closer for automatically closing a door after the door is opened; it contains a cylinder having three sections each with a different diameter. The middle section has the largest diameter. A pair of speed adjusting mechanisms are provided which are sleeved about a piston rod placed inside the cylinder. Each of the speed adjusting mechanism contains a rotatable piston head, which will rotate with the cylinder, and a fixed piston head, which will not rotate with the cylinder. By cooperated actions among the variously-sized sections of the cylinder and the pair of speed adjusting mechanisms, each speed adjusting mechanism can be separately adjusted to control the door closing speed at various stages of the door closing action. For example, the door closer can be designed such that the first speed adjusting mechanism is made to control the door closing speed during the first 10.degree.; whereas, the second speed adjusting mechanism is made to control the door closing speed after the first 10.

Abstract: A compartment confining construction comprises an opening and a closure unit movably mounted on the compartment confining construction for movement between a closing position and a fully opened position with respect to the opening. A fluid-based positioning unit is connected to both the compartment confining construction and the closure unit, the fluid-based positioning unit having two working chambers interconnected by at least one flow path, a movement of the closure unit corresponding to a flow of fluid from one chamber to another through the at least one flow path. A fluid flow control device is provided for controlling the flow of fluid through the at least one flow path and thereby controlling the movement of the closure unit. The fluid flow control device is actuatable by an electric actuating device. The flow of liquid occurs in response to movement of the closure unit when the closure unit is moved by an external force.

Abstract: A door closer (20) is attachable to a door (24) and includes a cylinder (36) which forms a chamber (44) in which a piston element (50) is movable to move fluid from the chamber to a reservoir (82) upon opening of the door. After the door (24) has been opened to a position, for example, of ninety-five to one hundred degrees, continued opening of the door causes the fluid to be compressed within the chamber (44) and to be directed only through a back check valve (95) to the reservoir (82). This results in the development of an adjustable "back check" condition to provide a counterforce to the continued opening of the door. A passageway (150) is formed in cylinder (36) to allow fluid to flow relatively freely from chamber (44) to reservoir (82) until an inward end (56) of piston element (50) has travelled a prescribed distance "x." This prescribed distance of travel represents the opening of door (24) to ninety-five to one hundred degrees from the door's normally closed position.

Abstract: A door closer having a housing defining a fluid containing chamber and a fluid reservoir and including a piston supported in the chamber for movement in one and an opposite direction in response to respective opening and closing movements of a door. A first fluid passageway defined by the housing provides communication between the chamber and the reservoir for the free passage of fluid from the chamber to the reservoir in response to initial movement of the piston in the one direction. A second fluid passageway spaced in the one direction from the first fluid passageway contains a ball check valve spring biased to closed position for resisting the flow of fluid from the chamber through the second passageway to the reservoir. The valve is threadably adjustable relative to the housing to regulate the resistance to fluid flow.

Abstract: An automatic door closing device comprises a base and an oil guiding loop. The base is provided in the direction of a longitudinal axis thereof with a canal and is further provided in the direction of a short axis thereof with a through hole. A sliding block and a spring are received slidably in an outer end portion of the canal.

Abstract: A door closer (20) is attachable to a door (24) and is formed with a chamber (44) in which a piston element (50) is movable to move fluid from the chamber to a reservoir (82) upon opening of the door. After the door (24) has been opened to a position, for example, of sixty to seventy-five degrees, continued opening of the door causes the fluid to be compressed within the chamber (44) and to be directed only through a back check valve (95) to the reservoir (82). This results in the development of an adjustable "back check" condition to provide a counterforce to the continued opening of the door. The adjustable valve (95) includes a spring biased ball (144), the biasing of which must be overcome by the force of the fluid being compressed in the chamber (44) to allow for fluid to pass through the valve to the reservoir (82).

Abstract: A door closer which comprises a damper having a body case including an arm fixed to a door, a rotational shaft formed in the body case, a pair of chambers filled with high viscous liquids, a pair of rotary blades respectively having passages with check valves on the rotational shaft, the rotary blades being rotated together with a rotational shaft by a sub case fixed with a sub arm against a return spring at the time of opening the door, the door being effected by the resistance force of the high viscous liquid against the closing door, a stationary plate fixed to the body case, an intermediate plate so engages as to be rotatable at a predetermined angle against the return spring, a movable plate so engaged with the sub case as to be rotatable together with the sub case, a plurality of rotary connectors respectively movably engaged with a plurality of through holes on the rotating circumferential line of the intermediate plate, and an angle clutch formed with recesses to be engaged with the rotary connectors

Abstract: To simplify the fabrication of the housing of an automatic door closing device with hydraulic damping, it is proposed to configure the housing as a tubular hollow cylinder 106 on which, externally, by means of one or more compactly superimposed covering elements 102, a bypass valve 121 is formed.

Abstract: A door holding mechanism for use with closure devices, having interacting members connected to the door that selectively, by touch, effect locking or sliding movement to permit unrestricted door movement or rigid positioning in one or more positions.

Abstract: A door closer wherein a housing defines a fluid-containing space and rotatably supports a shaft which is articulately connected with a pivotable door panel. A piston in the housing divides the space into a chamber and a compartment and has a toothed rack which mates with a pinion on the shaft so that the piston moves in the housing in response to rotation of the shaft as a result of pivoting of the door panel and vice versa. One or more springs in the chamber bias the piston in a direction to pivot the door panel toward closed position. A channel in the housing establishes communication between the chamber and the compartment during an initial stage of movement of the door panel from closed position at which time the piston moves in a direction to reduce the volume of the chamber.

Abstract: A damper comprising within a casing filled with viscous fluid a number of movable discs to be moved in response to the transmitted external force and a number of not interlocked fixed discs arranged in an alternative arrangement, wherein both movable and fixed discs are axially deflectable can maintain even clearances between the movable and the fixed discs due to the alignment effect of the discs without undergoing unreasonable stress that can damage the discs. The allowable limit of deflection of the fixed and movable discs can be made adjustable so as to modify the total drag of the damper. Sources of resilient restoring force may be provided to enhance the capability of adjustment. Moreover, the number or the size of the movable and/or the fixed discs can be made alterable to effectively modify the drag of the damper.

Abstract: A return apparatus includes a first hollow cylindrical member and a second hollow cylindrical member sleeved in the first cylindrical member to create a telescoping movement in a sealed relationship. The first cylindrical member has a first and a second closed end to define a first sealed chamber. The second cylindrical member has a first closed end protruding beyond the first closed end of the first cylindrical member and a second closed end having a flange radially extended therefrom to seal and engage movably with the inner face of the first cylindrical member in the first chamber. A floating piston is mounted in the axial bore of the second cylindrical member defining a second chamber and a third chamber. The third chamber is provided with a compressible gas. The first and second chambers are filled with fluid under the pressure of the compressible gas. In this way, the second cylindrical member can be retracted to an original position after it is pulled outward by an axially external force.

Abstract: A shock absorber for damping the movement of the body of an automobile is provided. The shock absorber comprises a pressure cylinder forming a working chamber operable to store damping fluid. The shock absorber further comprises a reciprocating piston disposed in the working chamber operable to divide the working chamber into first and second portions. An axially extending piston rod is disposed within the working chamber and is connected to the piston. Finally, the shock absorber includes an annular collar and a split ring for controlling the displacement of the piston.

Abstract: A door holding mechanism having interacting members with cooperating cam surfaces that selectively, by touch, effect locking or sliding movement to permit unrestricted door movement or rigid positioning in partial open conditions.

Abstract: A door holding device for door closers is described in which a door is held only at a predetermined angle of opening and in which the selected holding position can remain unchanged over a long period of time but can nevertheless be released by electrical means. For this purpose the switching of the door is effected, starting from a known mechanical door holding device which can be switched in and switched out, via a control unit which is biased into a door holding position by the hydraulic pressure which is in any event present in the closer and which can be released again via a magnetic valve.

Abstract: A damper for braking the opening speed of the hatch of a cassette tape holder of a recorder comprises a rotary member such as a gear member and a supporting member for supporting the rotary member, a viscous substance for producing a braking torque being charged in a clearance between the rotary member and the supporting member. The damper is characterized by being provided with an injection opening for injecting the viscous substance into the clearance and an air-escape portion for allowing air contained in the clearance to escape, the air-escape portion being positioned remote from the injection opening, whereby the clearance can be uniformly charged with the viscous substance without air being mixed therewith.

Abstract: An oil type damper comprises a housing formed of a basic member in the shape of a blind tube and a cap, a rotating member and a braking disc adapted to rotate jointly and accommodated within the housing, viscous oil applied to the braking disc, and at least one flexible membrane opposed to the braking disc so as to allow the braking disc to be sealed in the housing as covered with the oil. In this oil damper, when the oil serving to brake the rotary motion of the rotating member connected to a given door expands in volume because of rising temperature, the flexible membrane is deformed under the pressure of the expanded oil enough to absorb the voluminal expansion of the oil and prevent otherwise possible leakage of the oil from the housing.

Abstract: A gas spring for a hatch type door is disclosed, which comprises a cylinder, a piston received in the cylinder to divide the same into first and second chambers, a piston rod connected to the piston, a first device for providing a passage between the first and second chambers only when the piston moves in a direction to contract the second chamber, a second device for providing a passage between these chambers only when the piston rod is pushed against the piston by a force greater than a predetermined degree, and a third device for providing a passage between these chambers only when the piston is positioned within a predetermined area in the cylinder.

Abstract: An improved compression valve mechanism for a shock absorber comprising an upwardly facing annular valve seat on the shock absorber piston, an annular valve seat engaging member having an exterior periphery spaced closely from the interior periphery of the cylindrical shock absorber chamber providing a relatively small annular gap therebetween and a downwardly facing surface adapted to engage the upwardly facing annular valve seat, an annular seal mounted above the annular member in motion transmitting relation therewith, the seal being made of relatively rigid material and being split radially so as to be expandable radially outwardly and having an upwardly and inwardly facing generally frustoconical spring force transmitting surface and a peripheral sealing surface, and a coil spring above the seal having its upper end fixed with respect to the piston and having its lower end disposed in force transmitting relation with the force transmitting frustoconical surface of the seal so that the seal is biased ther

Abstract: A door closer assembly for controlling the operation of a door relative to a door frame includes a door closer mounted on the door and an articulated arm assembly which has one end attached to the door closer and the other end pivotally secured to a slide block which travels in a track mounted on the door frame. The slide block is affixed to a piston rod, which comprises part of a fluid piston-cylinder assembly also mounted on the door frame, and is located at the end of the track remote from the hinged edge of the door when the door is fully closed. When the door is opened beyond a predetermined angular position relative to the door frame the slide block moves within the track and in the direction of the hinged edge to another location within the track wherein it is releasably retained by the piston-cylinder assembly until the door is nearly fully closed by the reaction force of the door closer.

Abstract: An automatic door closer comprises a closer shaft connected to a door for turning therewith and being turnably mounted in the region of one end of an elongated fluid-filled housing. A cam disk fixed to the closer shaft cooperates over rollers carried by a slide to move the latter and a piston rod fixed thereto during opening movement of the door in a first direction. A first piston arranged in the housing divides the latter into a first and a second pressure space and is connected to the piston rod passing through a bore in the first piston for moving therewith in the first direction to thereby reduce the volume of the first pressure space while increasing the volume of the second pressure space. A coiled compression spring arranged about the piston rod biases the first piston to move in a second direction opposite said first direction. A second piston fixed to the free end of the piston rod projects beyond the first piston into a cylinder space formed in a plug closing the other end of the housing.