Abstract: A pneumatically adjustable lifting apparatus utilizes inflatable spring devices for lifting and precisely positioning a load at a desired location. Variations in the forces produced by the load cause the inflatable spring devices to expand or compress thereby allowing soft mating between components that need to be connected together, such as assembling or disassembling large threaded connections. Pneumatic pressure in the inflatable spring devices may be adjusted depending upon the particular load. The pneumatically adjustable lifting apparatus provides lightly damped vertical travel with a substantially linear force profile over a relatively wide displacement range. Recirculating linear ball bearings cooperate with the linear loading characteristics of the inflatable spring devices to minimize the vertical motion damping of the pneumatically adjustable lifting apparatus.

Abstract: A vehicle body includes a plurality of shock absorber housings positioned at right and left sides of the vehicle body and configured to cover and support shock absorbers of a vehicle, wherein a lower end of each of the shock absorber housings includes a flange unit comprising a plurality of flanges arranged along an outer periphery of the lower end of the shock absorber housing, and a connection member connecting the shock absorber housings to each other in a width direction of the vehicle body, wherein an end of the connection member is fitted between the flanges of the flange unit and is coupled to a corresponding one of the shock absorber housings.

Abstract: A vehicle body includes a plurality of shock absorber housings positioned at right and left sides of the vehicle body and configured to cover and support shock absorbers of a vehicle, wherein a lower end of each of the shock absorber housings includes a flange unit comprising a plurality of flanges arranged along an outer periphery of the lower end of the shock absorber housing, and a connection member connecting the shock absorber housings to each other in a width direction of the vehicle body, wherein an end of the connection member is fitted between the flanges of the flange unit and is coupled to a corresponding one of the shock absorber housings.

Abstract: A vehicle suspension damper comprises a cylinder and a piston assembly including a damping piston along with working fluid within the cylinder. A bypass permits fluid to avoid dampening resistance of the damping piston. A fluid path through the bypass is controlled by a valve that is shifted by a piston surface when the contents of at least one predetermined volume is injected against the piston surface which acts upon the valve. In one embodiment, the bypass is remotely operable.

Abstract: A bicycle comprising a frame; a handlebar assembly attached to an upper steering tube of the frame in such a way that at least the relative rotation between the two with respect to an upper axis is allowed, but the relative displacements between both in the directions perpendicular to the upper axis are restricted; a fork attached to a lower steering tube of the frame so that it has the same degrees of freedom relative to the lower axis between the fork and the lower steering tube as the degrees of freedom relative to the upper axis between the handlebar assembly and the upper steering tube; and a means for rotation transmission for transmitting at least partially a rotation of the handlebar assembly with respect to the upper tube into a rotation of the fork with respect to the lower steering tube.

Abstract: A work vehicle includes a chassis, a prime mover configured to move the chassis along a ground surface, and a suspension assembly that couples a wheel to the chassis. The suspension assembly includes a knuckle coupled to the wheel, a first suspension arm, and a suspension cylinder. The first suspension arm includes a first portion rotatably coupled to the chassis and a second portion extending away from the first portion and coupled to the knuckle. The suspension cylinder is rotatably coupled to the chassis and to a second suspension arm. The first suspension arm and the suspension cylinder are each configured to pivot relative to the chassis about a common pivot axis.

Abstract: A replaceable valve includes a spring preload adjuster and a spring. The spring is configured to be positioned at a first side of the spring preload adjuster. The replaceable valve includes a valve cap positioned at a second, opposite side of the spring preload adjuster. The valve cap is configured to attach to a shock absorber.

Abstract: A pneumatic seat support by itself supports a seat above a floor of a vehicle. The pneumatic seat support has upper and lower air chambers. The lower air chamber is a rigid cylindrical tube. The upper air chamber is a flexible cylindrical bellows, with a diameter greater than the diameter of the tube. Three or more linear shafts extending through the upper air chamber and into the lower air chamber provide a single-degree-of-freedom bearing support structure that allows vertical motion of the seat but withstands horizontal loads on the seat. When the seat moves vertically downward, it compresses air in both chambers, providing a seat support system with a natural oscillation frequency which is less than 2.4 Hz, and preferably in the range of 1.5-2.2 Hz.

Abstract: A bellows assembly for a vibration damper includes a bellows with a plurality of pockets with pocket walls and a pocket inner profile, a helical compression spring with windings consisting of a wound spring wire and pressure contact lateral faces. The helical compression spring is arranged in the bellows and the plurality of pockets extend coaxially to the longitudinal axis of the helical compression spring. Under pressure loading of the helical compression spring arranged in the bellows, the bellows folds together with the helical compression spring, wherein the wound spring wire is arranged at least in certain portions in the plurality of pockets, wherein the pocket walls of the plurality of pockets in which the wound spring wire is arranged at least in certain portions cover at least the mutually opposite pressure contact lateral faces of adjacent windings of the helical compression spring.

Abstract: A damper system for a vehicle is provided that includes a damper and actuator. The damper extends longitudinally along a damper axis between first and second damper ends. The actuator is separate and spaced apart from the damper. The actuator extends longitudinally along an actuator axis between first and second actuator ends. The damper and the actuator are arranged next to one another where the actuator axis is spaced from and substantially parallel to the damper axis. The damper and the actuator are positioned within a cylindrical packaging envelope that has a diameter of 300 millimeters or less. The cylindrical packaging envelope is an imaginary cylinder, which may be defined by one or more components of a vehicle's suspension system such as a coil spring or an upper suspension arm. The damper and the actuator are completely contained within the cylindrical packaging envelope.

Abstract: The present disclosure relates to a steering stabilizer for a vehicle. The stabilizer has a damper having a housing, a piston rod extending telescopically from the housing, and a coil spring disposed over the damper. An inner adapter assembly secures a first end of the damper to one of a wheel component or a body component of the vehicle. An outer adapter assembly is coupled to a distal end of the piston rod and couples to the other one of the wheel or body component. A one-piece spring seat is fixedly coupled to the housing. The coil spring is supported at a first end by the spring seat and at a second end by the outer adapter assembly. The spring seat enables the single coil spring to return the steering stabilizer to a central position regardless of whether the single coil spring is under tension or compression.

Abstract: A tensioner for tensioning a chain or belt span which uses two pistons. The movement of the two pistons may be coupled together. The first piston provides damping to the chain span and a second piston provides variable, dominant and automatically adjusting spring force to the chain span. The tensioner automatically adjusts the mean tension force to keep the chain or belt tension as low as possible without sacrificing chain or belt control, significantly improving drive efficiency at new chain or belt conditions and conditions with dynamic loads.

Abstract: A tensioner which adjusts the mean tensioner force to keep the chain tension as low as possible without sacrificing chain control, significantly improving drive efficiency as the chain wears and is subject to low dynamic loads.

Abstract: The landing gear systems, methods and apparatuses disclosed herein may comprise a shrink pump and a shrink valve that are capable of shrinking a landing gear by up to 40% of its available stroke, or more depending on the air spring configuration. The shrink pump may be configured to pump fluid (e.g., a hydraulic fluid) between an oil chamber, where hydraulic fluid is likely present and a shrink chamber to shrink the landing gear. Moreover, the shrink pump and shrink valve may be part of a strut shrink system.

Abstract: A bicycle frame includes a substantially rigid front frame portion and a substantially rigid rear frame portion. A link is connected to the rear frame portion by a first pivot and to the front frame portion by a second pivot. A frame segment is rigidly connected at a first end to one of the rear frame portion and the front frame portion and pivotably connected at a second end to other of the rear frame portion or the front frame portion by a third pivot. The frame segment is flexible proximate the second end.

Abstract: A tensioner for tensioning a chain span which uses two pistons. The movement of the two pistons may be coupled together. The first piston provides damping to the chain span and a second piston provides variable, dominant and automatically adjusting spring force to the chain span. The tensioner automatically adjusts the mean tension force to keep the chain tension as low as possible without sacrificing chain control, significantly improving drive efficiency at new chain conditions and conditions with dynamic loads.

Abstract: A drive device for a construction machine, which includes a speed reducer and a brake mechanism, wherein the speed reducer has a casing in which lubricating oil and the brake mechanism are provided, and wherein the brake mechanism includes: a ring-shaped brake piston; and a brake plate configured to generate a braking force by a pressing force of the brake piston, and wherein the brake piston has: a plurality of oil pockets provided in the brake piston at respective positions along a circumferential direction of the brake piston, each of the oil pockets formed as a space capable of storing lubricating oil; oil inlets allowing lubricating oil rising during operation of the drive device to be introduced into the oil pockets respectively; and oil outlets allowing lubricating oil stored in the respective oil pockets to be discharged.

Abstract: A tensioner which adjusts the mean tensioner force to keep the chain tension as low as possible without sacrificing chain control, significantly improving drive efficiency as the chain wears and is subject to low dynamic loads.

Abstract: A rear suspension bicycle in which a lower linkage member between the front triangle and the rear wheel swingarm includes a flexible portion of material rather than a discrete pivot point.

Abstract: A disposable positive displacement pump is disclosed. The pump includes a pump housing having head portion and a body, the head portion having one or more fluid passage openings. The pump also includes a rolling diaphragm internal to the pump housing and defining a fluid chamber within the pump housing. The pump further includes a piston drive unit configured to reciprocally drive the rolling diaphragm to move fluid in or out of the fluid chamber. A method of dispensing a fluid is also disclosed.

Abstract: A laterally tiltable, multitrack vehicle is disclosed. The vehicle includes a vehicle body and at least three wheels, first and second wheels of the three wheels being assigned to a common axle to form a first wheel pair. The vehicle includes at least one wheel control part suspending each of the first and second wheels of the wheel pair from the vehicle body. At least one resilient element supports each wheel control part on the vehicle body. The resilient element has a non-linear spring characteristic with a spring rate which increases in a compression direction and decreases in a rebound direction. The vehicle may be a motor vehicle.

Abstract: A positive displacement dosing system and method of dispensing a fluid including a plurality of disposable positive displacement pumps. The disposable positive displacement pumps each include a pump body having head portion and a base portion, with the head portion having one or more fluid passage openings. Each disposable positive displacement pump also includes a rolling diaphragm internal to the pump body and defining a fluid chamber within the pump body. The disposable positive displacement pump also includes a piston drive unit configured to reciprocally drive the rolling diaphragm to move fluid in or out of the fluid chamber. The positive displacement dosing system includes tubing connecting the fluid reservoir to the disposable positive displacement pump.

Abstract: A damper with an air spring includes: a damper main body having a cylinder and a piston rod inserted into the cylinder; and a cylindrical diaphragm attached to a side of the cylinder at a first end thereof and to a side of the piston rod at a second end thereof and forming an air chamber around the damper main body, in which a first attachment case to which the first end of the diaphragm is attached is fitted on an outer periphery of the cylinder, and an inner-diameter step portion of the first attachment case is brought into abutting contact with an upper end portion of the cylinder in an axial direction thereof, while a second attachment case to which the second end of the diaphragm is attached is fixed to the piston rod.

Abstract: A vehicle includes a chassis, a plurality of ground engaging elements supporting the chassis above a ground surface, a motor for driving at least one of the ground engaging elements to thereby propel the machine along the ground surface, and a chassis height adjustment system for selectively raising and lowering the chassis relative to the ground surface. A track width adjustment system is configured to shift the position of at least one of the ground engaging elements laterally relative to the chassis and a controller is configured to automatically actuate the track width adjustment system when the chassis height adjustment system is actuated to preserve a constant track width as the chassis moves up and down relative to the ground surface.

Abstract: The invention related to a device comprising at least three insulation modules distributed around vibration equipment. Each module comprises at least two rigid parts, at least one of said parts being an outer part fixed to the carrier structure and at least one of said parts being an inner part fixed to the equipment or the stand (3) thereof. At least one elastomer insulating plug connects an inner part and an outer part and at least one of said parts carries two longitudinal flexible abutments and two tangential flexible abutments which each have a free end facing another respectively outer or inner rigid part, said free end being at a distance from the inner part in an idle position. The invention can be applied to satellite equipment.

Abstract: An automobile includes an active suspension system and a leveling system. The leveling system receives high pressure fluid from the active suspension system in order to change static vehicle height and compensate for static load changes.

Abstract: Provided is a damping device including a cylindrical body sealed with an inner cover and an outer cover at both ends, a support rod coupled to one end of the cylindrical body to perform an axial motion, the support rod including a moving plate having a damping orifice in the cylindrical body, the support rod including a nut configured to adjust a length of the support rod at an inner side end received in the cylindrical body, and a buffering device configured to store elastic energy in one of a first spring and a second spring based on a moving direction of the moving plate, the buffering device including the first spring inserted in the inner cover, the second spring inserted in the outer cover, and a lubricant in the cylindrical body.

Abstract: A damper includes a vehicle-body-side mounting portion, an axle-side mounting portion, and a vehicle height adjusting mechanism for adjusting a distance between the vehicle-body-side mounting portion and the axle-side mounting portion. The vehicle height adjusting mechanism includes a first tubular member formed into a bottomed tubular shape, a second tubular member formed into a bottomed tubular shape and inserted from the bottom side into the first tubular member, and a stopper member having a shaft portion and a locking portion provided at a proximal end of the shaft portion. A distal end of the shaft portion is fixed to the bottom of the first tubular member. The shaft portion is inserted through a hole formed in the bottom of the second tubular member. The locking portion abuts on the bottom of the second tubular member.

Abstract: An air dampening assembly for an electronic device comprises a base member. A first piston housing is disposed on the base member. A second piston housing is disposed on the based member opposite the first piston housing. A sliding member is disposed between the first and second piston housing. A first piston is disposed on a first elongated member of the sliding member. The first piston housing is configured to receive the first piston. A second piston is disposed on a second elongated member of the sliding member. The second piston housing is configured to receive the second piston.

Abstract: The invention relates to a pneumatic spring device for a motor vehicle, including a rolling piston (4), a pneumatic spring cover (5) axially movable thereto, and an interposed elastomer covering as rolling bellows (6) with a trapped compressible air volume. According to the invention, at least one additional spring element (3) is connected in series to the pneumatic spring (2), with a radial bearing (14) of the rolling piston (4) and/or the pneumatic spring cover (5) being integrated as torsion compensation.

Abstract: A damper for a landing gear of a helicopter having a barrel, a piston defining a first hydraulic cavity between the piston and a bottom end of the barrel and a second hydraulic cavity between the piston and a top of the barrel, a stack of disc springs disposed within the first hydraulic cavity in a compressed state between the bottom end of the barrel and the piston. Each of the disc springs having a substantially concave side and an opposing substantially convex side, the disc springs stacked in an alternating pattern such that any two adjacent washers have their like sides positioned adjacent to each other. A spring disposed within the second hydraulic cavity such that the spring is compressed between the compression member and the top of the barrel when the piston is in an extended position. A hydraulic fluid is disposed inside at least a portion of the first hydraulic cavity and at least a portion of the second hydraulic cavity.

Abstract: A safety enhancement for a safety belt comprises an actuator housing mechanically coupled to a first end plate, a rotor blade, an orifice plate, a second end plate, a coil, and a spring cover by an actuator axel. The orifice plate comprises an orifice that allows hydraulic fluid to pass from a first side of the rotor blade to a second side of the rotor blade in order to increase or decrease tension on a safety belt to reduce user movement.

Abstract: A shock absorber includes a hydraulic compression stop. The hydraulic stop includes a pressure tube surrounding the pressure tube of the shock absorber and a piston in hydraulic communication with the interior of the pressure tube. The piston can be disposed within the pressure tube and can be attached to the pressure tube or to the shock absorber. The hydraulic stop can also include a hydraulic fluid chamber and the piston can be disposed within the hydraulic fluid chamber.

Abstract: A suspension device (S) comprises: an actuator (A) including a motion conversion mechanism (T) for converting rotational motion of a screw nut (1) to linear motion of a threaded shaft (2), and a motor (M) connected to the screw nut (1); and a fluid pressure damper (D) connected to the threaded shaft (2), wherein the threaded shaft (2) is formed in a cylindrical shape, a connecting shaft (30) for connecting a rod (31) or a cylinder (32) of the fluid pressure damper (D) to the threaded shaft (2) is inserted into the threaded shaft (2), and the connecting shaft (30) is connected to an end, opposite to the fluid pressure damper, of the threaded shaft (2). Accordingly, the connection between the actuator and the hydraulic damper is facilitated.

Abstract: An assembly includes a chassis coupled to a mounting surface via a mounting system. The mounting system includes a bolt, a dashpot, and a spring. The dashpot and the spring are configured to reduce vibration forces transferred from the mounting surface to the chassis. Techniques for forming the assembly are also described.

Abstract: A stabilizing device for axles of vehicles, such as motor vehicles, trailers, semi-trailers, or the like, including a hollow cylinder unit, which comprises a hollow cylinder containing a fluid therein, a piston unit with a piston which is arranged in the hollow cylinder and divides the hollow cylinder into at least two chambers, wherein the piston unit can slide relative to the hollow cylinder unit in that said piston unit can be moved from an original position to a deflected position, a pre-tensioning device which tensions the piston unit in the direction of the original position, and a control or regulating device which controls or regulates the fluid flow into/out of the chambers.

Abstract: Provided is a height adjustable suspension unit that can smoothly lift and lower a vehicle body without the need to supply fluid to a shock absorber. The height adjustable suspension unit includes: a shock absorber S having a cylinder 1 and an extensible rod 2 disposed in the cylinder 1 to be able to advance and retract, the extensible rod 2 having an end portion that is coupled to a chassis X; a coil spring 4 mounted around the extensible rod 2, the coil spring 4 having a lower end supported on a spring base 3 that is attached to the upper end of the cylinder 1; and a lifting and lowering mechanism D including a gear mechanism A that is rotationally driven by a power source, a power conversion section B that converts power transmitted from the gear mechanism A into power to move the cylinder 1 up and down, and a guide section C that guides the up and down movement of the cylinder 1.

Abstract: A solid state cup device that assists a coil over arrangement of an air suspension system for at least one motor vehicle wheel is disclosed. The device comprises at least one outer cup having a plurality of o-rings placed on the coil over arrangement. The system further includes at least one inner cup having a plurality of smaller o-rings, and which inner cup is placed on top of at least one spring. The at least one outer cup further includes at least one c-ring designed to prevent the at least one inner cup from sliding out of the at least one outer cup. With air injected into the at least one outer cup, the at least one inner cup may press down the at least one spring to provide tension on the at least one spring resulting in a smoother lift and lowering of the at least one motor vehicle.

Abstract: The invention concerns a vehicle oscillation device with a lower part (1) and an upper part (2, 2a, 2b) positioned higher and spring-mounted in relation to the lower part (1) in the vehicle longitudinal direction (21) and/or vehicle width direction (22) by a spring device (7, 7a, 7b, 8; 18), wherein the vehicle longitudinal direction (21) and/or the vehicle width direction (22) constitute spring travel directions (9, 11), wherein at least one damper (3, 3a; 4, 4a) is arranged which extends with its longitudinal extension in a plane defined by the vehicle longitudinal direction (21) and the vehicle width direction (22), is mounted on the lower part (1) pivotably about an axis (17, 24) oriented perpendicular to the plane, and is connected with a first end (5, 5a; 6, 6a; 16) to the upper part (2).

Abstract: A coil spring suspension designed for a handlebar-steered vehicle. The coil spring suspension generally includes a first tube, a coil spring, a shaft and a guide. A first end of the coil spring is disposed within the first tube and fixedly supported proximate a first end of the first tube. The coil spring extends beyond a second end of the first tube. The shaft fixedly supports a second end of the coil spring. The shaft and the first tube are slidably displaced relative to each other upon suspension loading to lengthwise compress the coil spring. The guide is disposed within the first tube and connected to the coil spring between the first and second ends of the coil spring. The guide is displaced with the coil spring under suspension loading and limiting lateral displacement of the coil spring.

Abstract: A suspension device (S) comprises: an actuator (A) including a motion conversion mechanism (T) for converting a linear motion to a rotational motion and a motor (M) connected to a rotary member (1) which performs the rotational motion in the motion conversion mechanism (T); a fluid pressure damper (D) connected to a linear motion member (2) which performs the linear motion in the motion conversion mechanism (T); an outer cylinder (27) connected to the actuator (A); and a bearing (34) attached to a rod (31) or a cylinder (32) connected to the linear motion member (2) of the fluid pressure damper (D) and slidably contacting with the inner circumference of the outer cylinder (27). This suspension device can improve reliability and vehicle ride quality.

Abstract: A wheel suspension is described with a wheel-guiding McPherson strut unit which has a helical compression support spring, a shock absorber which is connected on one end to the body and on the other end to the wheel, and a suspension arm, the helical compression spring being made such that the helical compression spring at least partially compensates for transverse forces which occur on the shock absorber without the action of the helical compression spring. To enable the weight of the helical compression spring to be reduced, the helical compression spring is constructed and arranged so that the stress in the spring is at least approximately, preferably exactly, the same on the side of the spring center line or line of action of the spring force facing the wheel as on the side facing away from the wheel. This makes it possible to reduce the weight throughout by roughly 10%.

Abstract: In the inside of a cylinder tube, there are provided a piston chamber and an adjusting chamber communicating each other, and these both chambers are filled with oil in a pressurized condition, and further, there are provided a piston moving in an axial direction in the piston chamber and a rod coupled to the piston. An elastic member is located in the inside of the adjusting chamber in a state that a reservoir tank is formed in the adjusting chamber by being compressed by pressurizing force of the oil, and impact is absorbed in such a way that the elastic member is caused to extend and contract by the oil flowing in/flowing out the reservoir tank by movement of the rod.

Abstract: A spring device at a swivelable hatch of a motor vehicle, having a gas spring and a helper spring between the body of the motor vehicle and the hatch. The hatch is a front hood which can be raised into a pedestrian protection position prior to an impact of a pedestrian on the front hood, by an actuator activated by a sensor device. The helper spring is preloaded with a preloading force which, in case of a malfunction in which the gas spring has no gas pressure or a reduced gas pressure, is sufficient to adjust the front hood into the raised pedestrian protection position and to hold the front hood in the raised pedestrian protection position prior to the impact.

Abstract: A suspension system for a vehicle has an upper control arm and an associated lower control arm for mounting a wheel on the vehicle body. A hydro-pneumatic spring is connected between one of the control arms and the vehicle body. A compensating spring is associated with the hydro-pneumatic spring and is operable to act in opposition to the force exerted by the hydro-pneumatic spring as the hydro-pneumatic spring approaches full extension.

Abstract: A suspension device (S) of the present invention comprises: an actuator (A) including a motion conversion mechanism (T) for converting a linear motion to a rotational motion, and a motor (M) connected to a rotational member (1) which performs the rotational motion in the motion conversion mechanism (T); a fluid pressure damper (D) connected to a linear motion member (2) which performs the linear motion in the motion conversion mechanism (T); a mount (22) connected to a sprung member of a vehicle; and suspension springs (38) and (38) interposed between the mount (22) and an unsprung member, the actuator (A) being elastically supported by the mount (22) through a rubber vibration isolator (21).

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: A plastic spring having a corrugated tubular body with connection surfaces at its ends for transmitting force between two structural component parts which are movable relative to one another. A connection surface of the plastic spring is constructed as a tubular body which engages in a cup element of one of the supporting structural component parts. The cup element can be filled with a displacement mass, and the tubular body accordingly carries out a displacing movement within the cup element for axially adjusting the preloading of the plastic spring.

Abstract: A support strut includes a strut isolator with a first strut end member and a second strut end member, the second strut end distal from the first strut end. The first strut end member includes an outer rigid housing with an inner cavity. The second strut end member includes an inner rigid member extending into the outer rigid housing inner cavity and includes an inertial track extending in a direction from the first strut end towards the second strut end. The inertial track has a first entrance end proximate the first strut end and a second entrance end proximate the second strut end. The isolator includes a first outer tubular elastomer disposed between the outer rigid housing and the inner rigid member. The isolator includes a second inner end tubular elastomer disposed between the outer rigid housing and the inner rigid member proximate the second strut end.

Abstract: The present disclosure relates to a spring system comprising a strut for arrangement between a dolly and a body of a rail vehicle with a cylinder and a piston displaceably received in the cylinder which bound a piston chamber, with the piston or the cylinder being connectable to the dolly and the other of the components being connectable to the body and with one or more spring which cushion the body with respect to the dolly, with a non-resilient hydraulic system which is in communication with the piston chamber and by means of which the amount of the hydraulic medium in the piston chamber can be varied for the purpose of adjusting the strut length, with an abutment member being provided by means of which the end position of the piston can be changed in the cylinder and with means being provided which are made such that the means actuates the abutment member when the piston chamber of the hydraulic system is pressure-less or the pressure in the piston chamber or in the hydraulic system falls below a value.