Abstract: The invention relates to a bearing for axially mounting a rotor of a gas turbine. Said bearing comprises a bearing body that is disposed stationary relative to the position of the rotor, a hydraulic piston arrangement which is accommodated by the bearing body, and a hydraulic system that is fluidically connected to the hydraulic piston- arrangement. In order to create a bearing which also absorbs bearing forces that occur due to high dynamic thrusts of the rotor while ensuring secure mounting of the rotor, a diaphragm is mounted between the hydraulic piston arrangement and the hydraulic system.