A clamping device for releasably holding a tool holder shank, the clamping device comprising: - a housing; - a spindle rotatably mounted inside the housing and having a front end, a rear end and a bore which intersects the front end and extends rearwardly therefrom, wherein a mounting portion for receiving the tool holder shank is provided at a front end of the bore; - a drawbar slidably mounted inside the bore so as to be reciprocally moveable in the bore along a longitudinal axis thereof between an advanced releasing position and a retracted locking position; - engagement members arranged around the drawbar at a front end thereof, wherein the engagement members, under the effect of a movement of the drawbar from the advanced releasing position to the retracted locking position, are moveable from a first position, in which the engagement members allow the tool holder shank to move into and out of said mounting portion of the bore, to a second position, in which the engagement members are in locking engagement with the tool holder shank and keep it secured to the spindle; - an actuating member arranged inside the housing, wherein the actuating member is slidably mounted to the spindle so as to be moveable in relation to the spindle in the axial direction thereof; and - a motion transferring mechanism arranged inside the housing, wherein the motion transferring mechanism is mounted to the spindle and configured to transfer a movement of the actuating member in a first axial direction in relation to the spindle into a movement of the drawbar from the advanced releasing position to the retracted locking position; characterized in that the clamping device further comprises: - two or more hydraulic actuators arranged in or mounted on the housing on different sides of the spindle and configured to move the actuating member axially in relation to the spindle, wherein each hydraulic actuator comprises one or more piston members (52a, 52b), each of which being slidably received in a space of the hydraulic actuator at the side of and at a distance from the spindle so as to be hydraulically moveable axially in this space in parallel with the longitudinal axis; and - a connecting element at least partly arranged inside the housing and configured to form a connection in radial direction between the actuating member and the piston members (52a, 52b) of the hydraulic actuators, wherein the connecting element is configured to transfer an axial movement of the piston members (52a, 52b) in relation to the housing into a corresponding axial movement of the actuating member in relation to the spindle. - a housing; - a spindle rotatably mounted inside the housing and having a front end, a rear end and a bore which intersects the front end and extends rearwardly therefrom, wherein a mounting portion for receiving the tool holder shank is provided at a front end of the bore; - a drawbar slidably mounted inside the bore so as to be reciprocally moveable in the bore along a longitudinal axis thereof between an advanced releasing position and a retracted locking position; - engagement members arranged around the drawbar at a front end thereof, wherein the engagement members, under the effect of a movement of the drawbar from the advanced releasing position to the retracted locking position, are moveable from a first position, in which the engagement members allow the tool holder shank to move into and out of said mounting portion of the bore, to a second position, in which the engagement members are in locking engagement with the tool holder shank and keep it secured to the spindle; - an actuating member arranged inside the housing, wherein the actuating member is slidably mounted to the spindle so as to be moveable in relation to the spindle in the axial direction thereof; and - a motion transferring mechanism arranged inside the housing, wherein the motion transferring mechanism is mounted to the spindle and configured to transfer a movement of the actuating member in a first axial direction in relation to the spindle into a movement of the drawbar from the advanced releasing position to the retracted locking position; - two or more hydraulic actuators arranged in or mounted on the housing on different sides of the spindle and configured to move the actuating member axially in relation to the spindle, wherein each hydraulic actuator comprises one or more piston members (52a, 52b), each of which being slidably received in a space of the hydraulic actuator at the side of and at a distance from the spindle so as to be hydraulically moveable axially in this space in parallel with the longitudinal axis; and - a connecting element at least partly arranged inside the housing and configured to form a connection in radial direction between the actuating member and the piston members (52a, 52b) of the hydraulic actuators, wherein the connecting element is configured to transfer an axial movement of the piston members (52a, 52b) in relation to the housing into a corresponding axial movement of the actuating member in relation to the spindle.