Abstract: A compact vehicle height control system is capable of changing the spring constant of gas springs to thereby control the vehicle attitude stabilizing characteristics so as to provide a comfortable vehicle ride. Pilot-controlled directional control valves are interposed in passages that connect first and second gas springs in parallel. When the pilot-controlled directional control valves are opened, the first and second gas springs are communicated with respective cylinders in parallel, whereas, when the directional control valves are closed, only the first gas springs are communicated with the cylinders, thereby changing the spring constant. The pilot-controlled directional control valves are hydraulically operable, thereby eliminating solenoid operated valves.

Abstract: A hydraulic damper has a valve mechanism adapted to generate a damping force during extension and contraction strokes of the damper. The valve mechanism includes a disc valve assembly consisting of a main disc valve for generating a damping force and an orifice for generating a damping force in low operation speed region of the damper. The orifce is provided with an additional disc valve for controlling the damping force generated.

Abstract: A damping force generating mechanism in a hydraulic damper includes a housing containing therein oil and an oil chamber partitioning member such as a piston. The mechanism includes a communicating passage provided in the oil chamber partitioning member and defining an annular valve seat on one end thereof and an annular valve plate provided on one end of the communicating passage and being deflectable toward and away from the valve seat for permitting the oil to flow in the communicating passage in one direction. The plate valve consists of a plurality of mutually overlapping annular plates, and at least one of the annular plates is deflected in the direction separating from the valve seat by a projection member which also is one of the annular plates.

Abstract: A hydraulic damper includes a dual-tube type housing consisting of inner and outer tubes, a piston slidably disposed in the inner tube and dividing the interior thereof into two oil chambers, a piston rod secured to the piston and extending to the outside of the housing, a reservoir chamber defined between the inner and outer tubes and containing therein oil and gas, a passage connecting one of the oil chambers through which the piston rod extends with the gas containing portion of the reservoir chamber, and a valve member formed of a resilient material and having a lip portion acting as one-way valve for allowing fluid flow in the passage only in the direction from the one oil chamber to the reservoir chamber. A substantial portion of the radially inner surface of the lip portion is supported by a rigid annular retaining member.

Abstract: A hydraulic damper is provided with a damping force adjusting mechanism. The damper includes a piston slidably positioned with a closed ended cylinder which functions to divide the interior of the cylinder into two chambers. Communication between the two chambers is provided by passageways partially defined by apertures and bores within the piston. Fluid flow between the two chambers via the passageways serves as the damping force. The damping force is made adjustable by a rotary valve positioned within one of the passageways which functions to vary the effective cross-sectional area of that passageway thus functioning as a damping force adjusting element. A device is provided to vary the damping force adjusting mechanism from the exterior of the hydraulic damper in accordance with a predetermined damping force.

Abstract: A cylinder device such as a hydraulic shock absorber, a gas spring or the like having a main body having an open end, a closure member screw-threadedly engaging the open end, of the main body, a rod guide disposed inside of the closure member, a piston rod extending slidably through center bores formed respectively in the closure member and the rod guide, pressurized fluid enclosed in the cylinder device, and a seal member interposed between the rod guide and the closure member. An escape passage has one end thereof communicating with the outside of the device and the other end thereof communicating with the screw-threading engaging portion between the closure member and the main body.

Abstract: A hydraulic shock absorber of the type including a tubular main body having of an inner tube containing oil and slidably receiving a piston and an outer tube surrounding the inner tube to define around the inner tube an annular reservoir chamber containing therein pressurized gas in the upper portion and oil in the lower portion. A rod guide closes the upper end of the inner tube, and a piston rod is secured to the piston and slidably extends through the rod guide and through a seal member closing the upper end of the main body.

Abstract: A shock absorber and suspension strut unit having an outer cylinder containing a predetermined amount of a damping liquid. An inner cylinder is mounted rigidly and concentrically in the outer cylinder and is arranged so as to form an intermediate concentric space between the cylinders. A movable piston rod assembly is movable relative to the double-cylinder assembly and has a piston slidably arranged within the inner cylinder for movement therealong. Check valves are provided in the piston for permitting selective fluid flow from one side of the piston to the other. Further, one or more communication passages are provided in an end of the inner cylinder which abuts the enclosed and the outer cylinder for allowing fluid passage therethrough mutually between a liquid chamber formed below the piston within the inner cylinder and lower part of the annular space formed by and between the cylinders. Thus, these spaces are a substantially unified liquid chamber.

Abstract: A hydraulic damper has a cylinder containing oil therein, a piston slidably fitted in the cylinder, a hollow piston prd extending from one side of the piston and projecting out of the cylinder, a tubular member mounted on the other side of the piston with the interior thereof communicating with the interior of the hollow piston rod, a connecting passage including the interior of the hollow piston rod and the interior of the tubular member and placing the opposite sides of the piston in communication, an actuating rod rotatably extending through the piston rod and being operable from the outside of the cylinder, and a valve body slidably received in the tubular member and connected to the actuating rod for changing the effective area of the connecting passage.

Abstract: A hydraulic damper of the type having a cylinder defining an actuating chamber receiving hydraulic oil therein, a piston working in the actuating chamber, a piston rod with one end thereof secured to the piston and the other end thereof projecting from one end of the cylinder, a resisting force generating device mounted on the piston for controlling oil flow across the piston when the piston reciprocates in the actuating chamber, and a volume compensating chamber disposed adjacent to the actuating chamber and receiving gas and hydraulic oil therein. The hydraulic oil is caused to flow between the actuating chamber and the volume compensating chamber through a small hole.

Abstract: A hydraulic damper of the type including a valve disc deflectable around the inner and outer peripheries thereof to form fluid passages around the outer and inner circumferences thereof when the damper is actuated in opposite directions. A movable valve seat defining an annular valve seat having a diameter intermediate the inner and outer diameters of the valve disc is disposed to cooperate with the valve disc such that the effective pressure receiving area of the valve disc is reduced when the valve disc deflects in one direction and the movable valve seat is movable substantially freely when the valve disc deflects in the other direction.

Abstract: A cylindrical container with a rod slidably projecting from one end thereof such as a hydropneumatic shock absorber or a gas spring, in which a seal member through which the rod extends in sliding sealing engagement is normally urged by a spring against the inner surface of one end of the container and is adapted to move inwardly against the spring force of the spring to form a gas filling passage along the inner surface of the container when a pressing force is applied on the seal member from outside of the container.

Abstract: A buffer includes an actuation cylinder filled with oil, a piston rod extending through the upper end of the cylinder for vertical movement in the cylinder, a piston provided at the lower end of the piston rod in sliding contact with the inner wall of the cylinder and having a damping action producing mechanism. The piston divides the interior of the cylinder into upper and lower chambers. An outer cylinder is disposed about the cylinder in a peripherally spaced relationship therewith to define a reservoir chamber therebetween, the upper portion of the reservoir chamber being filled with gas and the lower portion of the reservoir chamber being filled with oil. A passage communicates the lower oil filled portion of the reservoir chamber with the lower chamber of the cylinder. A passage communicates the upper gas filled portion of the reservoir chamber with the upper chamber of the cylinder through the outer periphery of the piston rod.

Abstract: A damping force generating device in a hydraulic shock absorber having at least two oil spaces therein and an oil space partitioning member on which the damping force generating device is mounted including an annular resilient valve disc controlling oil flow flowing thereacross in the opposite directions in response to the extension and compression strokes of the shock absorber. A second annular resilient disc is disposed overlapping the valve disc for delaying the valve opening time in either direction of the oil flow.

Abstract: A process for preparing substituted dibenzofuran or fluorenone-9 by the intramolecular cyclization of substituted diphenyl ether or benzophenone in the presence of a carboxylic acid salt of palladium and/or palladium organic complex.