An excavator boom mountable hydraulic tool, the tool comprising: an electric power generation assembly including: a hydraulic motor having a motor output shaft , and a motor non-contact coupling mounted on the motor output shaft; an electric generator having a generator input shaft and a generator non-contact coupling coupled to the generator input shaft, the motor non-contact coupling being drivingly coupled to the generator non-contact coupling; tool electrical components electrically coupled to the electric generator of the electric power generation assembly to receive power from the electric generator; characterized in that the tool is a high-pressure hydraulic tool and having a full rated pressure, in that the hydraulic motor has a sealed housing enclosing an entirety of the motor output shaft within an interior thereof, wherein the motor non-contact coupling is mounted on the motor output shaft within the sealed housing and the generator non-contact coupling is positioned entirely outside the sealed housing, and in that the tool further comprises a high pressure hydraulic tool circuit including a hydraulic tool load and the hydraulic motor of the electric power generation assembly coupleable between a hydraulic boom inlet line and a hydraulic boom return line; wherein both the hydraulic tool load and the hydraulic motor of the electric power generation assembly are designed to input hydraulic fluid up to the full rated pressure of the tool; and wherein the sealed housing of the hydraulic motor of the electric power generation assembly is designed to retain hydraulic fluid within the interior up to the full rated pressure of the tool so that no case drain or separate low pressure return line is necessary. an electric power generation assembly including: a hydraulic motor having a motor output shaft , and a motor non-contact coupling mounted on the motor output shaft; an electric generator having a generator input shaft and a generator non-contact coupling coupled to the generator input shaft, the motor non-contact coupling being drivingly coupled to the generator non-contact coupling; a hydraulic motor having a motor output shaft , and a motor non-contact coupling mounted on the motor output shaft; an electric generator having a generator input shaft and a generator non-contact coupling coupled to the generator input shaft, the motor non-contact coupling being drivingly coupled to the generator non-contact coupling; tool electrical components electrically coupled to the electric generator of the electric power generation assembly to receive power from the electric generator; characterized in that the tool is a high-pressure hydraulic tool and having a full rated pressure, in that the hydraulic motor has a sealed housing enclosing an entirety of the motor output shaft within an interior thereof, wherein the motor non-contact coupling is mounted on the motor output shaft within the sealed housing and the generator non-contact coupling is positioned entirely outside the sealed housing, and in that the tool further comprises a high pressure hydraulic tool circuit including a hydraulic tool load and the hydraulic motor of the electric power generation assembly coupleable between a hydraulic boom inlet line and a hydraulic boom return line; wherein both the hydraulic tool load and the hydraulic motor of the electric power generation assembly are designed to input hydraulic fluid up to the full rated pressure of the tool; and wherein the sealed housing of the hydraulic motor of the electric power generation assembly is designed to retain hydraulic fluid within the interior up to the full rated pressure of the tool so that no case drain or separate low pressure return line is necessary. <EOS>