Patent ID: 8919176

Claim:
A hydrodynamic tool for compression and/or cutting comprising: an electric motor with a drive shaft, a transformation mechanism connected with the drive shaft and suitable for transforming a rotary motion of the drive shaft into an oscillating translation motion of a translatable body, a hydraulic pump connected to the transformation mechanism and suitable for carrying out a pressure increase of a hydraulic liquid acting on an actuation piston in an actuation cylinder, in response to the oscillating translation movement, wherein the hydraulic pump comprises: a pumping cylinder having an intake opening in non-return communication with a tank of pressure fluid and a delivery opening in non-return communication with the actuation cylinder, a pumping piston received in the pumping cylinder and fixedly connected to the translatable body so as to translate together with it, an auxiliary piston received in the pumping cylinder and fixedly connected to the translatable body through the interposition of a switching spring with elastic preload, so that: when the pressure of fluid acting on the auxiliary piston is smaller than the elastic preload of the switching spring, the auxiliary piston and the pumping piston translate together with the translatable body, making a first pumping flow rate with a first pressure, when the pressure of fluid acting on the auxiliary piston is greater than the elastic preload of the switching spring, the auxiliary piston does not translate together with the pumping piston, making a second pumping flow rate with a second pressure, wherein the first pumping flow rate is greater than the second pumping flow rate and the second pressure is greater than the first pressure.