Method for hydraulically lowering tools onto a surface of an object

A method for hydraulically lowering tools onto a surface of an object with predeterminable force and/or predeterminable pressure, in which hydraulic fluid is fed from a pump via a feed line, in which three valves are interposed in a series arrangement, to a hydraulic cylinder, and the hydraulic cylinder raises and lowers a mechanical device comprising a lever, wherein a tool is attached to the mechanical device, which tool is lowered onto a surface of the object during a lowering motion of the piston of the hydraulic cylinder by closing a second valve, which is disposed in the feed line closest to the hydraulic cylinder, when the piston is to be moved for lowering the tool, wherein

• a third valve, which is disposed between the pump and the hydraulic cylinder upstream of a first valve, which is disposed upstream of the second valve in the flow direction of the hydraulic fluid for raising the tool, and the first valve are opened so that
• between the first valve and the third valve, a first pressure is set with a predetermined value corresponding to a pressure in the feed line and the hydraulic cylinder at which the predetermined pressure or force effect can be exerted by means of the tool on the surface of the object, and
• when a second pressure in the feed line between the hydraulic cylinder and the second valve is reduced to a value corresponding to the previously reached first pressure between the third valve and the first valve, the second valve is opened so that
• in the feed line up to the piston inside the hydraulic cylinder, the pressure is maintained at which the predetermined pressure or force effect of the tool is exerted on the surface of the object.