Mounting and dismounting
Using the SKF oil injection method the propeller is pressed onto the tapered seat hydraulically by a hydraulic ring or nut. The large drive up force needed to obtain the interference fit is greatly reduced by the oil forced between the mating surfaces during the entire assembly procedure. The thin film of oil that separates the surfaces not only reduces the friction forces but also minimize the risk of fretting damage to the contact surfaces.
When the required axial drive up is reached, the oil between the contact surfaces is released. A powerful grip is thus established between the hub and the shaft and all the shaft surfaces can be utilized for power transmission.
When dismounting, oil is injected between the surfaces and the propeller is released from its tapered seat by the axial component of the compression force. For safety reasons the hydraulic ring or nut is used to brake the propellers axial travel. The same technique can be used for mounting components like rudder pintles and tillers.
It is a great advantage to the user to know that SKF can supply all the equipment to fit components hydraulically. A complete range of hydraulic rings and nuts, pumps and high pressure oil injectors are available.