Abstract: In the illustrative embodiments described, the two compartments of the cylinder cavity of a gas spring of the piston-and-cylinder type, separated by a piston assembly, are connected by first and second passages extending across the piston. A valve arrangement on the piston assembly opens the second passage in response to movement of the piston assembly towards a terminal position in the cylinder and closes the second passage in response to movement of the piston assembly away from the terminal position. The first passage is open at all positions of the piston assembly remote from the terminal position. Releasable locking structure in the cylinder is operable to close the first passage as the piston assembly approaches the terminal position, thereby to hold the piston assembly in such terminal position until the locking force is manually overridden.

Abstract: In the illustrative embodiments disclosed, a pressurized cylinder-and-piston rod device, such as a gas spring, includes structure for releasably retaining the piston rod at a terminal position within the cylinder against the fluid pressure tending to expel it. Provision is also made for the fluid pressure to aid in further withdrawing the piston rod into the cylinder after the retaining structure has been engaged.

Abstract: A pneumatic spring of the piston-and-cylinder type constitutes a support column whose length may be adjusted when a valve connects the two cylinder compartments on opposite sides of the piston. The valve is normally closed by gas pressure and may be opened by a releasing rod coaxially movable in the bore of a tubular column member. An operating lever for the releasing rod passes radially through an opening in the tubular member and is coupled to the releasing rod during assembly of the apparatus by a cam face on the radially moving lever displacing the rod against the gas pressure in the cylinder, whereupon the rod drops into an axially open recess of the lever from which it can no longer be released because of the limited clearance in the column opening.

Abstract: A column which includes an elongated guide tube receiving a pneumatic spring of the piston-and-cylinder type in its bore. A bar is fixedly fastened to the piston rod member or the cylinder member of the spring in longitudinal alignment and extends in the guide tube bore from the associated spring member toward one of the two longitudinally terminal parts of the guide tube. A spring assembly extending about the bar is interposed between spring seats on the pneumatic spring member fixedly fastened to the bar and the one terminal part of the guide tube. Cooperating abutments on the bar and on the one terminal part of the guide tube limit movement of the bar toward the other longitudinally terminal part of the guide tube.

Abstract: An elongated coupling member is connectable to the upper link of a three point tractor lift and to an implement carried by the lift, such as a spreader. The member includes a piston slideably mounted in a cylinder and a hydraulic circuit between a space at each side of the piston. The piston can be adjusted to a set position in which the relative positions of the piston and cylinder are maintained by hydraulic fluid within the circuit and spaces. An overload device, such as a spring biased, one-way valve, is included in the circuit so that upon overload, the piston moves, usually to lengthen the coupling member and allow fluid to flow from one space to the other. In one version, an overflow space or reservoir is in the circuit to accomodate excess fluid when the piston is shifted and one space is larger than the other.

Abstract: A gas spring includes a cylinder having two axial portions of different cross section and two pistons mounted on a common piston rod and respectively matching the cross sections of the cylinder portions. The pistons are spaced on the piston rod so that they are either both in the wider cylinder portion or respectively received in the two portions. A first throttling passage permits flow of fluid between the two cylinder compartments separated by the larger piston, and a second throttling passage by-passes the smaller piston only during movement inward of the smaller cylinder portion to permit flow of fluid out of that cylinder portion. A valve arrangement is biased for sealing the two parts of the cylinder cavity separated by the smaller piston when the latter is in the smaller cylinder portion, but does not move inward of that portion. The valve arrangement responds to a sufficient, axially applied force for connecting the two cavity parts.

Abstract: A mechanical link member is provided which is easily variable in length for ease of connection yet rigid in operation by the use of hydraulic valve and screw-type adjustments. In addition to an interrupted flow position which prevents relative axial movement of the ends of the link member, the hydraulic valve has full flow and restricted flow positions to control the rate of length adjustment. A spring positions the mechanical link to a midrange position when the hydraulic valve is opened and the link ends are not attached to a load.

Abstract: A fluid flow control device suitable for controlling the flow of fluid between two chambers of a jack comprises a valve between each of the two chambers being controlled and a common chamber. The valves are controlled by pilot operated stops which, when retracted permit the valves to close fully but which, when extended hold the valves partially open. A source of make-up fluid can be connected to the common chamber, and the feed to the pilot valves can be tapped off the common chamber by way of a restriction. Alternatively, the pilot valves can be isolated from the common chamber and a separate source of pilot fluid provided. In this case, the common chamber can be permanently connected to a source of fluid under pressure which can be a fluid pressure accumulator.

Abstract: The piston in a gas spring of the piston-and-cylinder type is prevented from moving from one of its terminal positions under the pressure of the gas in the cylinder by a plunger on the piston projecting toward the closed cylinder end and received in an axial recess of a brake member on the cylinder by cooperating engagement elements on the plunger and brake member which may provide a friction fit or impede fluid flow into the recess.

Abstract: A stop member for limiting the range of adjustment provided by a positioning device. The positioning device is of the type wherein a piston is adjustable to various axial positions within a cylinder. The stop member has the form of a cup, coaxial with the cylinder and affixed to a portion of the piston rod which extends beyond the end of the cylinder, with the open end of the cup facing the cylinder. The diameter of the cup is sufficient to permit the end of the cylinder to advance into the cup as the piston is moved into the cylinder. The cylindrical wall of the cup is provided with axially-spaced slots. A stop element is inserted transversely to the axis through one of the slots and extends across the space within the cup to block the advancement of the cylinder into the cup, thereby limiting the relative movement of the cylinder with respect to the piston. In one embodiment, the stop element has a U-shape with its legs passing on opposite sides of the piston rod when the stop element is inserted.

Abstract: A hevy duty, retractable, hydraulic, telescopic shock absorber of the type employed on fire engines, artillery vehicles and the like includes a valve arrangement for venting the main cylinder to hold a floating absorber piston in any working position. The shock absorber includes a passageway between a damping fluid reservoir and the cylinder chamber. The passageway is in open communication with the cylinder chamber when the floating piston is in an extreme position. A valve closes the passageway when the floating piston is in a position other than the extreme position.

Abstract: A gas spring includes a cylinder receiving pressurized gas and liquid therein, a piston slidably disposed in the cylinder, a piston rod secured to the piston and extending to the outside of the cylinder through a first end thereof, a valve mechanism disposed in the cylinder for controlling movement of the fluid in the cylinder, thereby controlling movement of the piston in the cylinder, and a valve actuating element projecting to the outside of the cylinder through a second end thereof. The cylinder has a generally cylindrical portion extending from the second end thereof, and a valve operating member is pivotally supported on the extending portion of the cylinder.

Abstract: A stay for use with a cover or the like and having a cylinder containing a pressure fluid medium and a piston arranged for movement into and out of the cylinder. The piston rod carries a piston which is slidably arranged within the cylinder and which itself is mounted on the piston rod for axial displacement relative thereto and has at least one opening that allows the pressure fluid medium to flow through the piston. The piston rod itself has two abutments, the first being arranged in the region of the interior end of the piston and the second being spaced from the first abutment, these two abutments having the piston arranged between themselves and limiting the axial displacement of the piston with respect to the piston rod. Moreover, the piston rod carries a cover element which is likewise axially displaceable relative to the piston rod and is adapted to close the opening or openings of the piston.

Abstract: An adjustable gas cylinder control comprising the combination of a single tube defining a single cylinder bore, a single piston slidable in the tube and dividing the tube into a first and a second compartment, a first and a second end plug adapted to sealably fit within the ends of the tube, a single spindle or rod fixedly mounted to the piston and reciprocable in the tube, gas inlet means for charging the sealed first compartment of the tube with gas, and valve means mounted in the piston and spindle for allowing gas flow between the first and second compartments of the tube thereby adjusting the position of the piston in the tube. The tube itself is made of rolled welded sheet metal with its ends having a simple cold formed impression holding the first and second end plugs. Also provided is actuating means including a lever connected to the spindle for actuating the valve means thereby allowing gas flow between the compartments of the tube.

Abstract: A hydraulic positioner for maintaining a given separation between its attachment points and having a bidirectional detenting action whereby the given separation can be altered only by application of a sufficiently large overriding force. A closed cylinder is divided into two closed fluid-filled chambers by a slidable piston. Motion of the piston requires transfer of fluid between the chambers. The transfer flow is determined by preloaded check valves in the transfer flow path. The check valves are preloaded in opposite directions to achieve the bidirectional detenting action. A reservoir supplies fluid under a small positive pressure to one of the closed fluid-filled chambers to replace fluid lost through leakage.

Abstract: A length-adjustable gas spring is provided with a by-pass valve comprising a piston sealing element and a depression in the inner tube of the gas spring so that when the piston sealing element is pushed to a position adjacent the depression, the valve is opened.

Abstract: A pneumatic spring having a cylinder and a piston rod biased axially outward of the cylinder by compressed gas in the cylinder cavity may be stopped in an axially intermediate position of the rod by engagement of respective radial faces on an abutment member mounted on the rod for axial movement and on a rigid abutment member fixedly mounted on the cylinder and projecting into the normal axial path of the other abutment member which may be deflected manually from its normal path for release of the rod.

Abstract: A hydraulically or pneumatically controlled device for locking a piston in he bore of its cylinder at any point of its stroke, comprises, mounted on the piston, fluid-tight seals, a series of wedges, and annular jacks incorporated in the piston. The wedges are arranged to move in translation parallel to the axis of the cylinder under the effect of the annular jacks so as to absorb the increase in the radial plays between the piston and the bore of the cylinder on its pressurization. This peripheral extension which is produced between the bottom of the cylinder on its intake side and the fluid-tight end seal of the piston spaced furthest from it, is followed, after the release of the lateral walls of the cylinder, by a retraction of the lateral walls of the cylinder acting on the outer surface of the wedges. The latter exert a grip on the piston thus effecting positive locking by binding of the cylinder and of the piston.

Abstract: The height of a chair and the inclination of its back support may be varied by changing the respective, effective lengths of two pneumatic springs whose assembly forms the chair leg. The cylinder of one spring is coaxially received in the cylinder or the hollow piston rod of the other spring, and relative axial movement of the received spring and the receiving element of the other spring is limited or entirely prevented. A valve connects the two compartments separated in the cylinder of each spring and may be operated by a mechanism separate from the valve operating mechanism of the other spring.

Abstract: The present invention involves a spline element for a seat in a vehicle, in which the height of the seat can be adjusted without changing the spline initial stress, and wherein the initial stress of the spline can be adjusted without making a change in the height of the seat. This is achieved by means of a cylinder which provides an enclosed gas compression compartment against which a pair of pistons disposed at opposite ends of the cylinder can be adjusted from each end thereof. Each piston has flow channels provided therethrough which can be closed with the aid of a respective back stroke valve which can be set in motion at any time from the outside, thereby turning the piston into a floating piston.

Abstract: Automobile shock absorber is locked by this structure which includes a yoke clamped on the larger upper shell of the shock absorber and a collar pivoted thereon and embracing the lower piston shell. When solenoid tilts the collar, it locks the shock absorber piston shell against extension.

Abstract: A locking device in a gas spring including a cylinder, a free piston slidably disposed in the cylinder for dividing the interior of the cylinder into a gas chamber and an oil chamber, and a piston slidably disposed in the oil chamber and having a piston rod extending outwardly from the cylinder, the locking device comprises a free piston rod secured to the free piston and projecting outwardly from the cylinder, and means secured to the cylinder for engaging with and controlling the movement of the free piston rod relative to the cylinder.

Abstract: A lengthwise-adjustable, compressed-gas-filled gas spring, particularly for continuous height adjustment of chairs, seats, tables, or the like, has two cylinders, coaxially mounted one inside the other, and leaving an annular chamber therebetween. A piston and piston rod are displaceably provided within the inner cylinder, the piston sealingly dividing the cylinder into a first housing chamber, on the piston rod side, and a second housing chamber. The piston rod extends sealingly out of the cylinders. The first housing chamber has a fluid connection to the annular chamber at all times. The inner cylinder has a passageway therethrough near the end opposite the piston rod end, and is axially displaceable within the center cylinder between a first position at which the passageway is sealed off and a second position at which a fluid connection is allowed between the second housing chamber and the annular chamber.

Abstract: An adjustment assembly has two coaxially mounted cylinders fitting into one another with a piston displaceably mounted within the inside cylinder and dividing the inside cylinder into two fluid filled housing chambers. The piston is connected to a piston rod which is guided out of one end of the cylinder in a sealed manner. A pressure medium chamber is provided in the annular space between the cylinders and is separated in a fluid tight manner from fluid filled parts of the annular space by two axially displaceable separating pistons. The lower housing chamber has a fluid passageway to the lower portion of the annular space and the upper housing chamber has a fluid passageway to the upper part of the annular space. The inner cylinder may be axially displaced from outside the assembly to seal or open the upper passageway thus locking or unlocking the piston.

Abstract: A pneumatic spring of the piston-and-cylinder type suitable for balancing the trunk lid of a motorcar and like applications is equipped with a stop mechanism which stops relative axial movement of the piston or piston rod and of the cylinder in response to a force axially applied to the spring, but releases the cylinder and piston or piston rod from each other in response to an applied force greater than the first-mentioned force. Cooperating stop members on the cylinder and piston rod engage each other as long as the relative axial movement of the principal spring elements is stopped.

Abstract: An arrangement is provided for adjusting the damping force exhibited by a hydraulic shock absorber. Included is a valve near the piston including passages permitting the flow of fluid through openings in the piston. A linkage is provided which is rotatable about the piston rod to close any or all of the passages through the valve and thus regulate the damping force. The position of the linkage is determined by the interaction of the linkage with a stop member and the piston rod. The stop member is an element which may be extended through one end of the cylinder to engage an extension of the linkage to hold it in place while the piston rod bearing the valve is turned to open or close openings in the valve and thus change the damping force the shock absorber can exert. The stop member is adaptable to be retracted from contact with the linkage so that the adjustment will not be disturbed.

Abstract: In a column of telescopically adjustable height, the two coaxial telescoping members may be adjusted axially after a control button in an axial bore of one member is depressed. A bracket, longitudinally split into two members, passes into the bore through a radial opening of the one column member and is anchored axially and radially by conforming engagement with the column member. The operating lever for the control button is pivoted between the bracket members outside the column bore so that a small angular movement of the exposed lever part causes the terminal part of the lever in the bore abuttingly to engage the control button and to depress the same.