US Patent 8667789 Hydraulic pressure supply unit for a power screwdriver

The pressure supply unit has a pressure generating aggregate (10), which generates a supply pressure (PL) for the intermittent operation of a power screwdriver (11). So as to allow also a tensioning cylinder unit (33) to be operated alternatively to the power screwdriver (11), which requires higher pressure, a pressure intensifier (30) is provided which is included in a separate module (31) and generates high pressure (PH) from the supply pressure (PL). The reversal of the pressure intensifier (30) for carrying out strokes is achieved by the same stroke switch valve (20) which otherwise performs the reversal of the power screwdriver (11).