Abstract: An elastic connection element with variable rigidity for coupling together components that are spaced from each other. The connection element is a tubular component with coupling points which fix the components to the element. The rigidity of the element, in the state of maximum rigidity, is determined substantially by the coupling points. These are formed by a receiving eyelet and an elastomeric bush bearing press-fit therein. The region located between the coupling points forms a piston/cylinder unit, the interior of which comprises at least two chambers that are separated by the piston and which receive a hydraulic or a pneumatic medium. The chambers are interconnected with one another by a connection line containing a controllable valve. By at least partially opening the valve, the rigidity of the connection element can be reduced in relation to the state of maximum rigidity.

Abstract: A triple tube shock absorber includes a pressure tube, a reserve tube and an intermediate tube. The intermediate tube is disposed between the pressure tube and the intermediate tube. A tube ring is disposed between the pressure tube and the intermediate tube to isolate an intermediate chamber from a reserve chamber. The intermediate tube ends at a position spaced from a base valve assembly to allow for the reduction of diameter of the reserve tube without adversely affecting fluid flow.

Abstract: A shock absorber includes an external control valve which controls the damping characteristics of the shock absorber. The external control valve controls the flow of fluid between the lower working chamber of the shock absorber and the reservoir chamber and between the upper working chamber of the shock absorber. The damping characteristics are dependent on the amount of current being applied to a solenoid valve which controls a fluid valve assembly. A soft fluid valve assembly is disposed in series with the fluid valve assembly to allow for the tuning of the damping forces at low current levels provided to the solenoid valve.

Abstract: An object of the present invention is to provide a hydraulic cylinder enabling a reduction in a stress generated by the pressure of hydraulic fluid at a welded portion of a case containing a damping valve. A piston (5) coupled with a piston rod (6) is slidably inserted in a cylinder (2, 3) sealingly containing hydraulic fluid. A joint (17) is attached to the side wall of an outer cylinder (3) of the cylinder. A damping force is generated by controlling a flow of the hydraulic fluid caused by a sliding movement of the piston in the cylinder by a damping force generating mechanism (19) contained in the joint (17). A valve case (18) of the joint (17) has a reduced diameter at a connection portion (23) welded to the outer cylinder (3). The reduced diameter is smaller than the diameter of the damping force generating mechanism (19) contained in the valve case (18).

Abstract: An adjustable damping valve device, for a vibration damper, includes a first valve and emergency operation valve, both of which are actuated by a shared solenoid. The emergency operation valve carries out a relative movement relative to the first valve when passing from the emergency operation position into normal operation. A magnetic flux guiding element is arranged in the magnetic flux between the first valve and the emergency operation valve and determines the magnetic flux for the emergency operation valve and for the first valve.

Abstract: A rod acceleration reducing mechanism is provided in a bottom-side oil chamber in an inner tube. The rod acceleration reducing mechanism includes a housing having a cylindrical accommodating casing screwed onto a fastening bolt of a bottom valve and a cap, a free piston displaceably fitted in the housing to define variable chambers at vertically opposite sides thereof, and elastic disks applying an elastic resistance to the displacement of the free piston. The variable chambers formed in the housing are variable in volume in response to pressure changes in the bottom-side oil chamber and the reservoir chamber. Thus, rod vibration can be generated by the rod acceleration reducing mechanism to reduce generation of rapping noise during running of the vehicle.

Abstract: A piston with a piston rod coupled thereto is inserted in a cylinder, which sealingly contains oil. An oil flow generated by movement of the piston is controlled by a damping force generation mechanism, thereby generating a damping force. A separator tube is disposed around the cylinder, and the oil is transmitted to the damping force generation mechanism through a branch tube integrally formed on a cylindrical sidewall of the separator tube. The branch tube is tapered at the outer circumferential portion thereof with the outer diameter thereof reducing toward the distal end of the branch tube.

Abstract: The flow of hydraulic fluid induced by sliding movement of a piston in a cylinder is controlled by a pilot-type main valve and a pilot valve, which is a pressure control valve, thereby generating damping force. By thrust from a solenoid actuator, the valve-opening pressure of the pilot valve is controlled, and the pressure in a pilot chamber is also controlled to control the valve-opening pressure of the main valve. When there is a failure, a valve body of the pilot valve is retracted to abut against a fail-safe disk by spring force of a valve spring. Thus, damping force is generated by the fail-safe disk at the downstream side of the pilot valve, and the valve-opening pressure of the main valve is also controlled by the fail-safe disk to obtain an appropriate damping force.

Abstract: A shock absorber in which a flow of hydraulic oil caused by sliding movement of a piston in a cylinder is controlled by a pilot type main valve and a pilot valve to generate damping force. The valve-opening operation of the main valve is controlled by adjusting the pressure in a pilot chamber with the pilot valve. A valve block and a solenoid block are connected together into one unit and inserted into a casing before being secured with a nut. At this time, an actuating rod of the solenoid block is engaged with a pilot valve member retained by a pilot spring and a fail-safe spring in a cylindrical portion of a pilot body of the valve block.

Abstract: A shock absorber housing for a shock absorber of a vehicle comprises a tube, which has a tubular wall, and an attaching element joined onto the tubular wall, the attaching element determining a critical force introduction area of an introduction of a force into the tubular wall, the tube in a longitudinal direction being built up from a first tube section having a first tubular wall and at least a second tube section having a second tubular wall, the first tube section and the second tube section being joined together by their ends facing one another. The first tube section and the second tube section are joined together with a tubular wall overlap of the first and second tubular wall, which overlap extends in a longitudinal direction, the tubular wall overlap being situated in the critical force introduction area of the attaching element.

Abstract: The control valve is applied to a shock absorber, which comprises: a pressure tube (10); a piston (14) dividing the pressure tube (10) in compression and traction chambers (CC, CT) communicating with each other through the piston (14); a hydraulic fluid reservoir (20) provided with a selective bidirectional fluid communication with the compressor chamber (CC). The control valve (VC) communicates the traction chamber (CT) with the reservoir (20) and comprises a tubular body (40) provided with at least one radial passage (41) opened to the interior of the tubular body (40) and to the reservoir (20); a shutter pin (60) to be axially displaced within the tubular body (40), between a closing position and different open positions of the control valve (VC) for communicating the traction chamber (CT) with the reservoir (20); and an actuator means (A) for axially displace the shutter pin within the tubular body (40).

Abstract: A shock absorber includes an external control valve which controls the damping characteristics of the shock absorber. The external control valve controls the flow of fluid between the lower working chamber of the shock absorber and the reservoir chamber and between the upper working chamber of the shock absorber. The damping characteristics are dependent on the amount of current being applied to a solenoid valve which controls a fluid valve assembly. A soft fluid valve assembly is disposed in series with the fluid valve assembly to allow for the tuning of the damping forces at low current levels provided to the solenoid valve.

Abstract: A damping force variable valve includes a retainer having a main body connected at a central portion thereof to a high pressure part or portion of a shock absorber and having an outer peripheral region enlarging outwardly, and a spool rod integrally extending from the central portion and formed at a center thereof with a hollow portion having a spool inserted therein. The variable valve further includes a main disc disposed adjacent the retainer, a solenoid unit provided adjacent the spool rod and including a push rod for moving the spool when electrical power is applied, and an operating block installed adjacent the solenoid unit and including an enlarged portion coupled to the outer peripheral region of the main body.

Abstract: An adjustable damping valve including an actuator, which exerts an actuating force on a valve body against the force of a spring to influence the throttle cross section which determines the damping force, where an emergency valve is connected in parallel with the throttle cross section with respect to the flow direction of the damping medium, where the two control surfaces of the valve body move in the axial direction and can thus can come to rest alternately on the two valve seating surfaces, and where the valve body is divided into two parts in the longitudinal direction, and each valve body assembly has its own control surface.

Abstract: Self-pumping hydropneumatic spring strut includes a working cylinder divided into first and second working spaces by a working piston carried on a hollow piston rod; a high pressure chamber and a low pressure chamber partially filled with hydraulic damping medium, the high pressure chamber having a gas cushion and being connected to the second working space; and a piston pump including a pump rod extending into the hollow piston rod, the pump rod having a bore connected to the low pressure chamber, an end provided with a suction valve inside the hollow piston rod, and a deregulating opening, which is closable as a function of position of the working piston in the working cylinder. An adjustable damping valve located outside the external tube has a first flow connection connected to the first working space, and a second flow connection connected to the second working space and the high pressure chamber.

Abstract: An electronically-controlled damper arrangement includes a valve assembly. The valve assembly features a valve slide that carries at least two pistons. The first piston controls flow through two separate flow paths while the second piston controls damping provided by the valve slide. The first piston being both axially moveable and radially moveable within a valve housing.

Abstract: In a suspension spring adjusting apparatus of a hydraulic shock absorber, a mounting mating surface sealed by a spring adjusting case and a seal material of a case cover is formed in a flat surface shape, and an outer peripheral edge of the case cover is provided with a skirt portion covering over an outer peripheral surface of the spring adjusting case via a gap.

Abstract: A shock absorber has an external valve that controls the damping loads for the shock absorber. The external valve extends generally parallel with the axis of the shock absorber and is attached to the reserve tube of the shock absorber. The inlet to the external valve is in communication with an intermediate chamber which is in communication with the working chamber of the shock absorber. The outlet of the valve is in communication with the reserve chamber of the shock absorber. The external valve controls the damping loads in both a compression and an extension stroke of the shock absorber.

Abstract: A shock absorber includes an external control valve which controls the damping characteristics of the shock absorber. The external control valve controls the flow of fluid between the lower working chamber of the shock absorber and the reservoir chamber and between the upper working chamber of the shock absorber. The damping characteristics are dependent on the amount of current being applied to a solenoid valve which controls a fluid valve assembly. A soft fluid valve assembly is disposed in series with the fluid valve assembly to allow for the tuning of the damping forces at low current levels provided to the solenoid valve.

Abstract: A shock absorber includes an external valve which controls the damping characteristics of the shock absorber. The external valve controls the flow of fluid between the lower working chamber of the shock absorber and the reservoir chamber and between the upper working chamber of the shock absorber. The damping characteristics are dependent on the amount of current being applied to a solenoid valve which controls the movement of a plunger.

Abstract: A vibration damper including a cylinder in which a displacer carries out a translational movement. The displacer has a work piston which divides the cylinder into two work spaces. The work spaces outside the displacerfor each operating movement direction of the displacer are connected to damping valves by a flow connection. Every flow connection has only one flow direction through a check valve arrangement. The flow connection has a plurality of inflow ports which are offset in axial direction starting from the work spaces and is formed by a bypass channel, and a plurality of damping valves are connected to the bypass channel and admit damping medium via the inflow ports.

Abstract: A damper device is manufactured from a single integrated body. The damper device comprises a damping chamber portion, a valve housing portion with adjustable valve devices and a pressurization reservoir portion. The internal volume of the damping chamber portion is divided by a piston into a compression chamber and a return chamber and the internal volume of the pressurization reservoir portion is divided by a member that is acted upon by a pressure that pressurizes the damping medium in the device. The three different portions are arranged substantially parallel to one another and the internal volume of the valve housing is connected both to the pressurized interior of the pressurization reservoir and to both chambers of the damping chamber part so that the damper always functions with a positive pressure in both the compression and the return chamber. The body is extruded as a single workpiece with alternating heat-conducting channels and fins on its outer surface.

Abstract: A hydraulic vibration damper has a cylinder that is filled with a damping medium, displaceably accommodates a working piston disposed on a piston rod, through which the damping medium can flow, and is divided by the piston into two chambers. There is an equalization chamber that is connected with the working chamber, a pressure channel connected with the chamber on the piston rod side, and a controllable setting valve module connected with the pressure channel and the equalization chamber. The setting valve module has a pilot valve arrangement having a pilot pressure chamber and a pilot valve. The pilot pressure chamber is hydraulically separated from the main valve, and is connected with a valve chamber by a connection channel and at least one throttle point. A pressure element counteracts opening of the main valve, and pressure that acts on the main valve can be varied by the pilot valve.

Abstract: A damping valve (102) comprises: a first valve element (16); a first valve seat (15) in which the first valve element (16) is seated; a second valve element (26) placed in series with the first valve element (16); a second valve seat (25), placed between the first and second valve elements (16) and (26), in which the second valve element (26) is seated; an biasing mechanism (30) for biasing the second valve element (26) toward the second valve seat (25) and biasing the first valve element (16) toward the first valve seat (15) via the second valve element (26); a first liquid chamber (106); a second liquid chamber (104); and a third liquid chamber (107).

Abstract: A bicycle shock absorber and methods for differentiating between rider-induced forces and terrain-induced forces includes a first fluid chamber having fluid contained therein, a piston for compressing the fluid within the fluid chamber, a second fluid chamber coupled to the first fluid chamber by a fluid communication hose, and an inertial valve disposed within the second fluid chamber. The inertial valve opens in response to terrain-induced forces and provides communication of fluid compressed by the piston from the first fluid chamber to the second fluid chamber. The inertial valve does not open in response to rider-induced forces.

Abstract: Disclosed is a solenoid valve assembly of a shock absorber wherein a plug the position of which is threadedly adjusted is prevented from escaping. The solenoid valve assembly includes a tubular spool rod having a female threaded portion formed on one end thereof, a plug including a male threaded portion threadedly coupled to the female threaded portion and a head portion having a diameter lager than that of the male threaded portion, the plug being threadedly adjusted in position with respect to the spool rod. The assembly further includes one or more ring-shaped spacers positioned adjacent or contiguous the male threaded portion for filling a space between an end surface of the spool rod and the head portion, thereby providing fixing torque to the plug the position of which is adjusted.

Abstract: An air pressure proportional damper includes a first chamber and a second chamber. The first chamber is fluidly attached to the second chamber through an air adjustment valve. The air adjustment valve regulates flow from the first chamber to the second chamber in proportion to air pressure received from an accompanying air spring.

Abstract: In a shock absorber of a vehicle, when a moving speed of a piston rod in relation to a cylinder tube is slow and first and second input forces are externally applied to the shock absorber, damping forces of pressure side and extension side first damping force generating devices are larger than that of pressure side and extension side second damping force generating devices. On the other hand, when the moving speed is fast, the damping forces of the pressure side and the extension side second damping force generating devices are larger than that of the pressure side and the extension side first damping force generating devices. A gas enclosure chamber filled with gas is connected to a first chamber through a free piston.

Abstract: In a hydraulic shock absorber structured such that a vehicle body side tube and an axle side tube are slidably fitted, and a plurality of adjusting portions are provided in a cap sealed to an upper end opening portion of the vehicle body side tube, a plurality of adjusting portions are arranged side by side in a plan view of the cap.

Abstract: A damper device includes a cylinder body and a piston body. At least one of the cylinder body and the piston body is attached to an article subject to damping so that the damping is applied to a movement or a relative movement of the article subject to the damping. The damper device has a run-through hole formed in an inner recess part of the cylinder body facing the piston body, and a stopper body having a shaft part, which is inserted into the run-through hole. A dimension of insertion of the shaft part of the stopper body into the run-through hole changes by a change of pressure caused by a movement of the piston body.

Abstract: A bicycle shock absorber and methods for differentiating between rider-induced forces and terrain-induced forces includes a first fluid chamber having fluid contained therein, a piston for compressing the fluid within the fluid chamber, a second fluid chamber coupled to the first fluid chamber by a fluid communication hose, and an inertial valve disposed within the second fluid chamber. The inertial valve opens in response to terrain-induced forces and provides communication of fluid compressed by the piston from the first fluid chamber to the second fluid chamber. The inertial valve does not open in response to rider-induced forces.

Abstract: A shock absorber includes an external control valve which controls the damping characteristics of the shock absorber. The external control valve controls the flow of fluid between the lower working chamber of the shock absorber and the reservoir chamber and between the upper working chamber of the shock absorber. The damping characteristics are dependent on the amount of current being applied to a solenoid valve which controls a fluid valve assembly. A soft fluid valve assembly is disposed in series with the fluid valve assembly to allow for the tuning of the damping forces at low current levels provided to the solenoid valve.

Abstract: A variable damping valve of a shock absorber is capable of properly adjusting a damping force according to read conditions, travel conditions and the like while a vehicle is traveling, thereby improving ride comfort and control stability. A flow of oil is controlled to generate a damping force and the damping force is simultaneously adjusted according to pressure in a pilot chamber. The damping valve comprises an upper retainer communicating with a high-pressure side and a main valve installed below the upper retainer. The main valve comprises a valve body defining a pilot chamber, a disk ring installed on a top surface of the valve body, and a housing for containing the valve body and the disk ring and integrally confining the valve body and the disk ring by being curled at upper and lower ends of the housing.

Abstract: A damping force variable valve includes a main valve provided between a high pressure section and a low pressure section, for allowing a flow of oil from the high pressure section into the low pressure section when the main valve is opened, the main valve being capable of being opened or closed depending on a pressure of the high pressure section, an initial preload and a pressure of a control chamber; a first variable orifice provided between the high pressure section and the control chamber, for controlling the pressure of the control chamber; a fixed orifice provided between the control chamber and the low pressure section; and a second variable orifice provided between the high pressure section and the low pressure section.

Abstract: A shock absorber according to the present invention includes a pressure tube having a working chamber disposed therewithin. A piston is slidably disposed within the working chamber and divides the working chamber into an upper working chamber and a lower working chamber. An intermediate tube is disposed around the pressure tube and the working chamber to define an intermediate chamber. A reserve tube is disposed around the intermediate tube. A collar is attached to the intermediate tube. The collar is defined by a shoulder portion extending generally lateral to the intermediate tube and a radial neck portion extending generally perpendicularly to the intermediate tube. An external control valve includes a valve seat received within the collar in an installed position. The external control valve is attached to the reserve tube.

Abstract: A shock absorber includes a shock rod and piston which are disposed within a fluid chamber within a shock body. The piston separates the shock body fluid chamber into a compression fluid chamber and a rebound fluid chamber. A reservoir fluid chamber accommodates the entry of the shock rod into the fluid chamber as the shock absorber compresses under shock forces. The compression fluid chamber is in fluid communication with the reservoir fluid chamber through a third chamber or passage. A first valve may control passage of fluid from the compression fluid chamber into the passage. Second and third valves may be disposed within the passage in parallel with each other and in series with the first valve. The third valve may include an easily accessible knob disposed outside the shock body.

Abstract: A shock absorber includes a pressure tube with a piston slidably disposed therein. A separate valve includes a fluid circuit for fluid low in rebound and a fluid circuit for fluid flow in compression. Each fluid circuit includes a variable orifice which allows selection between a firm rebound with a soft compression, a soft rebound with a soft compression, and a soft rebound with a firm compression. Each variable orifice is in communication with a blowoff valve in such a manner that they provide a variable blowoff feature to the blowoff valves.

Abstract: A shock absorber having a pair of valve assemblies which include an acceleration sensitive valve which couples the working chamber of the shock absorber to the shock absorber's reservoir chamber through a fluid path to provide a soft damping characteristic for the shock when the shock absorber experiences acceleration beyond a specific amount. A compression valve assembly and a rebound valve assembly are also provided which controls the fluid flow through the piston and the base assembly, respectively, to provide a firm damping characteristic for the shock absorber during low acceleration movement.

Abstract: A shock absorber having a pair of valve assemblies which include an acceleration sensitive valve which couples the working chamber of the shock absorber to the shock absorber's reservoir chamber through a fluid path to provide a soft damping characteristic for the shock when the shock absorber experiences acceleration beyond a specific amount. A compression valve assembly and a rebound valve assembly are also provided which controls the fluid flow through the piston and the base assembly, respectively, to provide a firm damping characteristic for the shock absorber during low acceleration movement.

Abstract: A shock absorber includes a pressure tube with a piston slidably disposed therein. A separate valve includes a fluid circuit for fluid low in rebound and a fluid circuit for fluid flow in compression. Each fluid circuit includes a variable orifice which allows selection between a firm rebound with a soft compression, a soft rebound with a soft compression and a soft rebound with a firm compression. Each variable orifice is in communication with a blowoff valve in such a manner that they provide a variable blowoff feature to the blowoff valves.

Abstract: An air chamber (53) of a damping force adjusting mechanism (49) disposed in a hydraulic shock absorber (3) of a damping force adjusting type communicates with an air chamber (7) of an air spring through a tubular path (57). A free piston (51) is transferred in accordance with the pressure of the air chamber and a spool (46) is transferred to shift a damping force. The damping force presents a soft characteristic both on the extending side and on the retracting side in a usual status, presents a hard characteristic on the extending side and a soft characteristic on the retracting side when the pressure of the air chamber is high, and presents a soft characteristic on the extending side and a hard characteristic on the retracting side when the pressure of the air chamber (7) is low. The damping force can be obtained, which approximates the damping force control on the basis of a so-called sky-hook theory.

Abstract: The present invention provides a shock absorber having improved damping. On the base of the shock absorber there is fastened the bottom of a barrel on which rests the counter-acting spring which urges in expansion the piston of the shock absorber. The barrel contains damping fluid and has a piston which is axially movable with lateral seal. The shock absorber also has an external secondary flow dampening device which is connected to the base of the shock absorber via a tube. In the strut base, and the connecting appendage there is a plug adjustment which moves laterally and limits an alternative path of flow for the liquid through the base flow damper and the piston flow damper respectively. By acting on the plug adjustments it is possible to adjust the braking level in expansion of the strut. Each flow damper also is affixed with a shim. The shim on the piston flow damper will flex at an appropriate pressure in the expansion phase, thereby damping the reaction of the strut to expansion.

Abstract: A device, e.g. a pressure regulator, for realizing an opening and/or closing function in connection with the force-velocity curves of the device incorporates two parts which work away from and towards each other at different velocities and accelerations, e.g. slide and housing. The parts work with a stroke and determine, in dependence upon the present size of the stroke, the passage of a fluid by way of a restrictor function realized by the parts. At least the one part (the slide) is subjected to force on both its sides. The restrictor function is made up of at least two part-restrictors which can be simultaneously actuated by a respective stroke and thereupon vary, preferably successively, their restrictor sizes differently from each other in dependence upon the respective stroke size. In the restrictor function, a passage of fluid is herein obtained which produces a smooth curve shape in the introductory and concluding part of the respective opening or closing function.

Abstract: A damping force control type hydraulic shock absorber includes a plunger having a small-diameter main body portion slidably guided by a first fixed core made of a magnetic material. The plunger has a large-diameter attracted portion at an end thereof closer to a second fixed core. The diameter (D2) of the attracted portion is set larger than the diameter (D1) of the main body portion (D2>D1), thereby increasing the area of the mutually opposing surfaces of the attracted portion and the second fixed core. Accordingly, attraction force acting on the attracted portion can be increased without reducing the magnetic flux density at the main body portion.

Abstract: A pressure operated valve is provided including an adjusting device, a spring and a vent connection. The adjusting device is axially movably arranged in a pressure chamber defined in the valve and comprises a valve body and a pressure intensifier. A space between the valve body and valve face defines a valve passage cross section. The spring is operatively arranged for holding the pressure intensifier in a floating arrangement in the pressure chamber. The pressure intensifier has a first side exposed to a pressure in the pressure connection opening and a second side facing away from the pressure connection opening. The second side of the pressure intensifier and the adjusting device define a low pressure chamber within the pressure chamber. The vent connection is an inflow restrictor arranged between the lower pressure chamber and a space having a lower pressure than the low pressure chamber.

Abstract: The flow of a hydraulic fluid between connecting ports caused by sliding movement of a piston in a cylinder is controlled by a fixed orifice and the flow path area determined by ports that is varied by a spool, thereby directly controlling orifice characteristics. At the same time, the pressure in a pilot chamber is changed by the pressure loss between the ports to change the valve opening pressure of a main valve, thereby controlling valve characteristics. An orifice passage is provided in parallel to the ports. Thus, when the flow path area determined by the ports is restricted, variations in the flow path area attributable to machining accuracy or the like can be absorbed by the flow path area of the orifice passage provided in parallel to the ports. Therefore, stable “hard” damping force characteristics can be obtained.

Abstract: The flow of a hydraulic fluid caused by sliding movement of a piston in a cylinder is controlled by a disk valve and extension- and contraction-side main valves, thereby generating damping force. By controlling the valve opening pressures of the disk valve as a pressure control valve with respect to extension- and compression-side valve seats with a proportional solenoid actuator, damping force can be directly controlled independently of the piston speed. Moreover, the pressures in pilot chambers are changed to control the valve opening pressures of the extension- and compression-side main valves. Because the disk valve is placed between the extension- and compression-side valve seats, it is possible to simultaneously select different damping force characteristics for the extension and compression sides.

Abstract: The flow of a hydraulic fluid caused by sliding movement of a piston is controlled through a sub-disk valve, a main disk valve and a disk valve to generate damping force. A coil is energized to urge a plunger in the valve closing direction against spring force from a spring, thereby adjusting the relief pressure of the disk valve and thus controlling the damping force. The pressure in a back-pressure chamber varies according to the relief pressure of the disk valve. Thus, the valve opening pressure of the main disk valve is also adjusted. An abrupt input is absorbed by relieving the pressure from the back-pressure chamber by deflection of the disk valve. Because “soft” damping force characteristics, which are often used, are maintained with a small electric current, the power consumption can be reduced.