To achieve the coupling between the shaft and the rudder blades on military ships is required the use of an hydraulic system for the operations.

The system developed by FPT is composed by two hydraulic nuts of particularly small dimensions in relation to the axial load provided, and optimized for the insertion on the blade. The hydraulic nuts have a peak pressure of 1.600 bar and a maximum stroke of 10 mm.

The connection between the conical surfaces of the blade and rod takes place by interference and the nut allows to obtain the value of the push-up of the project that guarantees the required coupling. The nuts are driven by FPT hydraulic hand pumps model PDS18, two-stage high pressure pump.

Subsequently, the locking ring nut is screwed and the stroke obtained during the operation of the push-up is maintained over time. The FPT hydraulic nuts thus remain on-board on the ship and allow to keep the coupling during time.