The Design of Rolling Bearing Mountings

81 Crane hookThe load suspended from a crane hook often has to beswivelled before being lowered. Therefore, the hooksof heavy-duty cranes are designed for these swivellingmotions.Bearing selection, dimensioningSince the weight of the payload acts vertically downward,the load is pure thrust. Therefore, loose radialguidance of the shaft in the crosshead is satisfactory.The load carrying capacity of the bearing is based onits static load rating. A thrust ball bearing FAG51152FP with a static load rating C 0 = 1,020 kN ismounted. Based on the maximum hook load of1,000 kN plus a safety margin of 10 %, the index ofstatic stressing f s = C 0 /P 0 = 1,020 / 1,100 = 0.93; i. e.,permanent deformation occurs at maximum load.However, it is so small that it does not interfere withthe swivelling of the load.The bearing is adjusted against the collar at the hookshaft by means of a locknut. This prevents the shaftwasher from separating when the crane hook is set onthe ground.Machining tolerancesThe bearing seats are machined to j6 (washer) and toH7 (housing).Lubrication, sealingThe bearing assembly is packed to capacity withlithium soap base grease with EP additives (FAG rollingbearing grease Arcanol L186V). Maintenance of thebearing is not required. Above the crane hook nut asheet steel cap is provided which protects the bearingagainst contamination.81: Crane hook mountingFAG 116