Abstract: In the case of a vibration damper with a by-pass (32, 32a) between an annular working chamber and a compensating chamber (28), there is in the by-pass (32, 32a) a shut-off valve assembly (36) with a valve shut-off element (42) and a valve seat (40b). The valve shut-off element (42) is for its part subject to the pressure (p.sub.1) in a first section (32) of the by-pass and on the other to the pressure (p.sub.2) in a control chamber (48). The cross-section of a control chamber outlet (46c) can be controlled by an outlet cross-section dimensioning device (52). The shut-off valve assembly (36) is so constructed that at maximum control chamber outlet cross-section the valve shut-off element (42) begins to be lifted off the valve seat (40b) when the throughflow rate through the control chamber outlet (46c) amounts to at least 0.2 times the total throughflow rate through the shut-off valve assembly (36) which becomes adjusted to a damper velocity of 1 m/sec.

Abstract: According to an illustrative example of this invention, the piston of a hydraulic oscillation damper is provided with a traction valve, i.e. a valve which is intended to damp the outward movement of the piston rod. This traction valve includes two valve discs and a valve member. The valve member is biased towards a closed position and urges the valve discs against a valve face of the piston. In response to a predetermined pressure difference between the two working chambers on both sides of the piston, a flow passage is opened by lifting the valve discs and the valve member from the valve face. Below said predetermined pressure difference, a preliminary restricted flow passage exists. This preliminary restricted flow passage extends in series across the radially inner circumferential edge of a first valve disc adjacent to the piston and through radially inner edge recesses and through radially outer edge recesses of a second valve disc adjacent to the first valve disc.

Abstract: In a double-tube vibration damper the flow of liquid from the lower working chamber to the reservoir chamber is controlled by a bottom valve. This bottom valve has additionally the function of hydraulic abutment for the piston rod when the piston rod approaches its innermost position. An abutment spring is connected with the inner end of the piston rod. This abutment spring cooperates with a control body being a part of the bottom valve and being urged towards a minimum damping position by a return spring. When the abutment spring abuts against the control body at a predetermined position of inward movement of the piston rod the control body is displaced towards a maximum damping position. The control body cooperates with a flow passage. Various embodiments of the flow passage are proposed in order to vary the characteristics of the bottom valve with respect to its function as hydraulic abutment.

Abstract: In a shock absorber unit for vehicles of the double-tube type a piston rod guiding and sealing unit is provided adjacent a first end of a cylinder and a container surrounding the cylinder, and a bottom valve unit is provided at a second end of the cylinder and the container, respectively. The cavity within the cylinder is divided into two working chambers by a piston unit. The piston unit is connected to a piston rod extending through the piston rod guiding and sealing unit. The cavity within the cylinder is filled with a damping liquid. The compensation chamber defined radially between the cylinder and the container is partially filled with damping liquid and partially filled with gas. Adjacent the piston rod guiding and sealing unit, there is provided a by-pass connection the working chamber adjacent the piston rod guiding and sealing unit and the compensation chamber. This by-pass defines a throttling flow cross-sectional area.

Abstract: A hydraulic vibration damper featuring reduced noise characteristics wherein a first and a second damping valve system operate in response to fluid pressure to control flow of damping fluid in each direction of movement, respectively, of a piston of the damper. The first and second damping valve systems include a preliminary throttling aperture, an aperture disc defining a preliminary aperture located downstream relative to the direction of fluid flow through the respective damping valve systems, and a noise reduction mechanism for producing a post-throttling effect downstream of the preliminary aperture, the noise reduction mechanism being formed by a baffle plate located to be impinged by fluid flowing through the preliminary aperture, the baffle plate being arranged to define a quieting duct immediately adjacent the baffle plate upstream thereof.