The Design of Rolling Bearing Mountings

58–59 Spherical roller thrust bearings as rudder carriersSpherical roller thrust bearings are used when the topbearing mainly has to take up the weight of the rudderand shaft. This is the case for all rudder drives notloaded by lateral forces, such as for rotary vane steeringgears and four-cylinder engines, which do not operatespade-type rudders.The two designs, N and W, for rudder carriers, differonly in their sealing.Bearing selection, dimensioningThe shaft diameter is determined according to formulaeof the Classification Societies. Thus the bore diameterof the rolling bearing is fixed. Due to the highaxial load carrying capacity a spherical roller thrustbearing FAG 29284E.MB with the dimensions 420 x580 x 95 mm is mounted directly on the shaft. Thebearing's index of static stressing f s ≥ 10.The welded housings are extraordinarily flat – theyprotrude just slightly beyond the deck or mountingbase. This provides advantages especially for largersteering engines, since the rudder shaft extension canbe kept short due to the low mounting and dismountingheight.Powerful springs under the bearing outer ring providea permanent positive contact of rollers and raceways.The supplementary plain bearing also accommodatesradial forces, if for example a cylinder in a four-cylindersteering engine fails.Machining tolerancesShaft h7. The housing is relief turned to ensure axialspring preload via the housing washer.Lubrication, sealingDuring mounting, the cavities of the spherical rollerthrust bearings and housings are completely filled withlithium soap base grease (consistency number 2 with EPadditives). As with radial spherical roller rudder bearings,there are also two designs (N and W) in the caseof rudder carrier bearings. Only the seal differs:FAG RS9284N.1..... rudder carrier bearings have feltseals, the rudder carrier bearings FAG RS9284W.1.....are sealed with seawater-proof shaft sealing rings.Both designs have a V-ring seal at the housing cover.58: Rudder carrier bearing FAG RS9284N.1..... 59: Rudder carrier bearing FAG RS9284W.1.....81 FAG