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 (16, 23), 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 (16, 23), 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 (16, 23), 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 (16, 23), 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 (16, 23), 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.