Clamping device, designed as a collet chuck, with a housing defining a clamping axis with a base body, an actuating unit which is held axially adjustable in the housing, a clamping sleeve in the form of a collet chuck, which is held on the actuating unit in order to be adjusted axially with the latter and which has a central receptacle, open towards a front side of the housing, for a component to be clamped, and a clamping ring closed in the circumferential direction, which is fixed to the housing, wherein engagement surfaces (16, 17) corresponding to one another are formed on the outside of the clamping sleeve and the inside of the clamping ring, which surfaces engage with one another and interact in order to convert an axial clamping movement of the actuating unit and thus of the clamping sleeve, in particular directed towards the rear, into a radially inwardly directed elastic deformation of the clamping sleeve in order to clamp a component, wherein hydraulic expansion clamping means are provided, which are designed and suitable for releasably fixing the clamping ring to the housing, characterized in that the housing has a central opening open to a front side, and the hydraulic expansion clamping means comprise a pressure chamber formed in the housing which can be acted upon by a hydraulic medium, and surrounds the central opening in an annular manner or has a plurality of pressure chamber sections distributed over the circumference, a thin wall being provided between the central opening and the pressure chamber, which wall can be elastically deformed radially inwards by increasing the pressure in the pressure chamber in order to fix the clamping ring in the central opening in a force-locking manner. a housing defining a clamping axis with a base body, an actuating unit which is held axially adjustable in the housing, a clamping sleeve in the form of a collet chuck, which is held on the actuating unit in order to be adjusted axially with the latter and which has a central receptacle, open towards a front side of the housing, for a component to be clamped, and a clamping ring closed in the circumferential direction, which is fixed to the housing, wherein engagement surfaces (16, 17) corresponding to one another are formed on the outside of the clamping sleeve and the inside of the clamping ring, which surfaces engage with one another and interact in order to convert an axial clamping movement of the actuating unit and thus of the clamping sleeve, in particular directed towards the rear, into a radially inwardly directed elastic deformation of the clamping sleeve in order to clamp a component, wherein hydraulic expansion clamping means are provided, which are designed and suitable for releasably fixing the clamping ring to the housing, characterized in that the housing has a central opening open to a front side, and the hydraulic expansion clamping means comprise a pressure chamber formed in the housing which can be acted upon by a hydraulic medium, and surrounds the central opening in an annular manner or has a plurality of pressure chamber sections distributed over the circumference, a thin wall being provided between the central opening and the pressure chamber, which wall can be elastically deformed radially inwards by increasing the pressure in the pressure chamber in order to fix the clamping ring in the central opening in a force-locking manner.