Shock absorber with adjustable damping force, comprising a pressure tube filled with damping medium, in which a piston on an axially movable piston rod divides a work chamber into a piston-side and a non piston-side chamber, whereby there is a damping medium flow between the two work chambers, which is divided into a main flow and a bypass flow, a damping valve device consisting of a damping valve body, with a main stage valve for each flow direction, each of which is formed by a main stage valve body, and a pilot stage valve which activates the main stage valve, an adjustable actuator, which controls a flow connection between the control chamber and a work chamber, whereby the control chamber is limited axially by the first and second spring-loaded main stage valve bodies, whereby the first main stage valve body, during the inflow from the closed valve position into an open position, is moved axially into the control chamber toward the second main stage valve body, which is held in the closed valve position by the damping medium, and when the inflow is in the reverse direction, the second main stage valve body is moved out of the closed valve position into an open position, axially toward the first main valve stage body which is in the closed valve position.

A vibration damper is disclosed having a valve actuation device and a housing, in which housing the valve actuation device can be located. The valve actuation device has a controllable coil form, a coil core, and a movable armature for executing an actuation motion. At least a portion of the housing of the vibration damper can represent a magnetic return body for the magnetic flux generated by the coil form.