The hydraulic nut consists essentially of a piston, a cylinder and an integrated needle shut-off valve. The hydraulic nut is pressured up to the desired pre tensioning force while the needle shut off valve is open. The parts to be tensioned are now fixed. The introduced pressure is locked by closing the needle shut-off valve. Afterwards the pressure at the hydraulic aggregate can be released. This design is used when machine parts have to be clamped or positioned. It is particularly suitable for the clamping of rotating components that must be replaced in a short time. Frequently used applications are machine tools, cutting, straightening, cropping and sanding machines.
The advantages of this design are the simple operating work in the small size and the fast replacement time of the machine components. With the appropriate sensors (BomAS) a pressure monitoring during the operational phase can also take place, if they were included in the control circuit (Emergency stop or shutdown).