The Design of Rolling Bearing Mountings

38 Steering king pin of a truckA variety of steering king pin mounting arrangementsare possible. The bearing arrangement with two adjustedtapered roller bearings for accommodating the axialloads is generally used in driven truck front wheels. Inother cases the axial loads are accommodated by thrustball bearings or tapered roller thrust bearings. Sincethe radial mounting space for king pin bearing mountingarrangements is usually very limited the radialloads (steering and guiding forces) are accommodatedby a plain bearing made of bronze and drawn cupneedle roller bearings which provide for easy steering.Mounting with a tapered roller thrust bearingThe shock loads on the steering king pin are very high.Therefore, the thrust bearing must have a high loadcarrying capacity and be mounted with zero clearanceor preload. As the king pin performs only slight slewingmotions no cage is required so that the number ofrolling elements and, consequently, the load carryingcapacity can be increased.The example features a full-complement tapered rollerthrust bearing as the thrust bearing. It has a profiledshaft-washer raceway and a flat housing-washer raceway.The sealed bearing is held together by a pressedsteel cap, which simplifies mounting.The bearing is filled with special grease; it can be relubricatedif necessary. Openings in the sealing lip andthe elasticity of the sealing material ensure the escapeof the spent grease.The clearance between the knuckle and the crossmember is compensated for by shims. In this way, thethrust bearing can have zero clearance at best, whichmeans higher shock-type loads. Experience has shownthat this can be taken into account by means of an impactfactor of f z = 5...6, in the case of adjusted taperedroller bearings with an impact factor of f z = 3...5.The shaft washer of tapered roller thrust bearings islocated by a relatively loose fit on the steering kin pin(g6); the housing washer has no radial guidance.38: Steering king pin of a truckFAG 58