Abstract: Hydraulic fluid is fed to a hydraulic cylinder via a feed line, and the hydraulic cylinder raises and lowers a mechanical device with a tool, where a lowering motion of the tool is reached by closing a second valve. Thereby, a third valve and a first valve are opened so that a first pressure is set between the first valve and the third valve, which corresponds to a pressure in the feed line and the cylinder at which the predetermined pressure or force effect can be exerted with the tool on the surface of the object. 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, the second valve is opened so that a pressure is maintained in the feed line up to the piston inside the hydraulic cylinder.