A portable, battery-operated hydraulic unit for hydraulic rescue tools , in particular for spreading and/or shearing tools, comprising - a control device - at least one hydraulic pump ; - at least one first and one second pressure line , which are coupled to a pressure outlet of the hydraulic pump ; - a hydraulic tank for a hydraulic fluid ; - at least one battery pack ; - an electromechanical interface for coupling and decoupling, as required, from the at least one battery pack ; - a mechanical-hydraulic interface for connecting the hydraulic rescue tool ; - and at least one electric motor for driving the at least one hydraulic pump , characterized in that a pressure relief valve is formed, which is arranged such that, when a maximum pressure is reached in at least one of the pressure lines , the hydraulic fluid is returned to the hydraulic tank via the pressure relief valve and a return line coupled to it, and that a pressure relief valve status detection device is configured to detect the response of the pressure relief valve , and that the control device is configured to reduce the rotational speed of the electric motor as a consequence of the detection of the response of the pressure relief valve , wherein the control device is configured such that it never reduces the rotational speed of the motor below a defined lower limit value. - a control device - at least one hydraulic pump ; - at least one first and one second pressure line , which are coupled to a pressure outlet of the hydraulic pump ; - a hydraulic tank for a hydraulic fluid ; - at least one battery pack ; - an electromechanical interface for coupling and decoupling, as required, from the at least one battery pack ; - a mechanical-hydraulic interface for connecting the hydraulic rescue tool ; - and at least one electric motor for driving the at least one hydraulic pump , characterized in that a pressure relief valve is formed, which is arranged such that, when a maximum pressure is reached in at least one of the pressure lines , the hydraulic fluid is returned to the hydraulic tank via the pressure relief valve and a return line coupled to it, and that a pressure relief valve status detection device is configured to detect the response of the pressure relief valve , and that the control device is configured to reduce the rotational speed of the electric motor as a consequence of the detection of the response of the pressure relief valve , wherein the control device is configured such that it never reduces the rotational speed of the motor below a defined lower limit value. a pressure relief valve is formed, which is arranged such that, when a maximum pressure is reached in at least one of the pressure lines , the hydraulic fluid is returned to the hydraulic tank via the pressure relief valve and a return line coupled to it, and that a pressure relief valve status detection device is configured to detect the response of the pressure relief valve , and that the control device is configured to reduce the rotational speed of the electric motor as a consequence of the detection of the response of the pressure relief valve , wherein the control device is configured such that it never reduces the rotational speed of the motor below a defined lower limit value. <EOS>