A gas spring system comprising: a first part which defines a cylinder, which comprises a longitudinal axis and which is closed at a first end along the longitudinal axis, a piston which is arranged to be movable in the cylinder along the longitudinal axis, a piston rod which is connected to the piston and projects out through a second end of the cylinder, a separating piston, which is arranged to be movable in the cylinder along the longitudinal axis between the piston and the first end, gas which is contained in the cylinder between the separating piston and the first end, and liquid which is contained between the separating piston and the piston, wherein the gas spring system comprises an expansion chamber for the liquid, wherein the gas spring system comprises a pressure regulating device, which is adapted to control the liquid transport between the cylinder and the expansion chamber in dependence of the temperature, thereby keeping the force characteristics of the gas spring substantially independent of the temperature, wherein the pressure regulating device comprises a measuring liquid chamber, which contains measuring liquid, and a pressure tube in which a pressure spindle is movably arranged, the position of the pressure spindle in the pressure tube being dependent on the volume of the measuring liquid and the liquid transport between the cylinder and the expansion chamber being adapted to be controlled by the position of the pressure spindle, the measuring liquid chamber is arranged in the piston rod, and the piston rod comprises a piston rod cylinder, the measuring liquid chamber being arranged in a measuring liquid piston which is movably arranged in the piston rod cylinder, wherein the pressure regulating device comprises a valve mechanism which is fixedly arranged relative to the piston, said valve mechanism comprising a regulating space, which is coaxial with the pressure tube and in which the pressure spindle is movably arranged, wherein the valve mechanism comprises a first liquid line for conducting liquid from the cylinder to the expansion chamber, a first valve which is arranged in the first liquid line for controlling the liquid flow through the first liquid line, a second liquid line for conducting liquid to the cylinder from the expansion chamber, and a second valve which is arranged in the second liquid line for controlling the liquid flow through the second liquid line, the first valve and the second valve being controlled by the axial position of the pressure spindle relative to the valve mechanism. a first part which defines a cylinder, which comprises a longitudinal axis and which is closed at a first end along the longitudinal axis, a piston which is arranged to be movable in the cylinder along the longitudinal axis, a piston rod which is connected to the piston and projects out through a second end of the cylinder, a separating piston, which is arranged to be movable in the cylinder along the longitudinal axis between the piston and the first end, gas which is contained in the cylinder between the separating piston and the first end, and liquid which is contained between the separating piston and the piston, wherein the gas spring system comprises an expansion chamber for the liquid, wherein the gas spring system comprises a pressure regulating device, which is adapted to control the liquid transport between the cylinder and the expansion chamber in dependence of the temperature, thereby keeping the force characteristics of the gas spring substantially independent of the temperature, wherein the pressure regulating device comprises a measuring liquid chamber, which contains measuring liquid, and a pressure tube in which a pressure spindle is movably arranged, the position of the pressure spindle in the pressure tube being dependent on the volume of the measuring liquid and the liquid transport between the cylinder and the expansion chamber being adapted to be controlled by the position of the pressure spindle, the measuring liquid chamber is arranged in the piston rod, and the piston rod comprises a piston rod cylinder, the measuring liquid chamber being arranged in a measuring liquid piston which is movably arranged in the piston rod cylinder, wherein the pressure regulating device comprises a valve mechanism which is fixedly arranged relative to the piston, said valve mechanism comprising a regulating space, which is coaxial with the pressure tube and in which the pressure spindle is movably arranged, wherein the valve mechanism comprises a first liquid line for conducting liquid from the cylinder to the expansion chamber, a first valve which is arranged in the first liquid line for controlling the liquid flow through the first liquid line, a second liquid line for conducting liquid to the cylinder from the expansion chamber, and a second valve which is arranged in the second liquid line for controlling the liquid flow through the second liquid line, the first valve and the second valve being controlled by the axial position of the pressure spindle relative to the valve mechanism.