Clamping device, designed as a collet chuck , with a housing defining a clamping axis (X) 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 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 (X) 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 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. <EOS>