Spring element which is adjustable in its stiffness by hydraulically generated pressure, suitable for pressures from 100 bar to 1500 bar, comprising (i) two or more elastomer layers and one or more non-elastic interlayers, where the elastomer layers are separated from one another by the non-elastic interlayers and the non-elastic interlayers have a centrally arranged opening or hole, so that the spring element has, at least in the interior, a continuous elastomeric core region to which the individual elastomer layers are connected, and (ii) at least one hydraulic device (4, 7, 9, 11, 12), which is mounted at the upper and/or lower end of the layer-like spring element and causes compression of the elastomer material in the vertical direction to the layers of the spring element by introduction of a hydraulic fluid into the spring element by means of hydraulic pressure and thus leads to the formation or enlargement of a displacement space containing hydraulic fluid in the elastomeric core region of the spring element, where (a) an elastic, correspondingly shaped pressure membrane, is arranged between the elastomer layers of the spring element and the displacement space and is securely connected at its edge to the hydraulic device or parts thereof, so that a membrane space containing hydraulic fluid forms, which corresponds to the displacement space in the case of a hydraulic pressure, and (b) the hydraulic device is connected to the membrane space via a hydraulic line, characterised in that the hydraulic device comprises one or more sealing elements (10, 10a, 6, 21, 22, 24) which have a pre-tension and are arranged in such a way that they generate an increased pressure, compared with the pressure in the membrane space, on the pressure membrane in the region of their secure connection to the hydraulic device, so that the membrane space is closed off in a pressure-tight manner from the layers of the spring element on the one hand and from the hydraulic device or parts thereof on the other hand. (i) two or more elastomer layers and one or more non-elastic interlayers, where the elastomer layers are separated from one another by the non-elastic interlayers and the non-elastic interlayers have a centrally arranged opening or hole, so that the spring element has, at least in the interior, a continuous elastomeric core region to which the individual elastomer layers are connected, and (ii) at least one hydraulic device (4, 7, 9, 11, 12), which is mounted at the upper and/or lower end of the layer-like spring element and causes compression of the elastomer material in the vertical direction to the layers of the spring element by introduction of a hydraulic fluid into the spring element by means of hydraulic pressure and thus leads to the formation or enlargement of a displacement space containing hydraulic fluid in the elastomeric core region of the spring element, where (a) an elastic, correspondingly shaped pressure membrane, is arranged between the elastomer layers of the spring element and the displacement space and is securely connected at its edge to the hydraulic device or parts thereof, so that a membrane space containing hydraulic fluid forms, which corresponds to the displacement space in the case of a hydraulic pressure, and (b) the hydraulic device is connected to the membrane space via a hydraulic line, (a) an elastic, correspondingly shaped pressure membrane, is arranged between the elastomer layers of the spring element and the displacement space and is securely connected at its edge to the hydraulic device or parts thereof, so that a membrane space containing hydraulic fluid forms, which corresponds to the displacement space in the case of a hydraulic pressure, and (b) the hydraulic device is connected to the membrane space via a hydraulic line,