The Design of Rolling Bearing Mountings

51 Kiln trucks for sand lime brick worksOperating conditionsIn sand lime brick autoclaves the wheelset bearings ofthe kiln trucks are exposed for many hours to hotsteam of approximately 200 °C at 16 to 22 bars. Dueto corrosion hazard the bearing location should beprotected against penetration of the steam which isstrongly alkaline.BearingsSealing requires major attention when designing thebearing arrangement. The best solution is the use ofpulverized synthetic FAG sealing agent and solid lubricantArcanol DF. This lubricant is suitable for temperaturesranging between –200 °C and +300 °C and resistsalmost any chemical even at high temperatures. Itis non-ageing and water repellent. The powder ispacked into the bearing location penetrating into allcavities of the arrangement and forming a lubricatingfilm between balls and raceways, balls and cage andalso between outer ring and housing bore. The film inthe housing bore ensures easy bearing displaceability,even after prolonged operation. This protects the bearingagainst detrimental axial preload.In addition to lubrication Arcanol DF also acts as asealing agent. It settles in the sealing gaps of the axlepassage and protects the inside of the bearings againstthe ingress of alkaline condensate.The bearings are designed for a truck with two wheelsetsaccommodating a total weight F r of 43 kN.The bearing load for each bearing is relatively low atF r /4 allowing the use of inexpensive FAG6208.R200.250.S1 deep groove ball bearings.Considering the high operating temperatures thebearings have a particularly large radial clearance(200...250 or 250...350 microns), are heat-treatedaccording to S1 (200 °C) and are dimensionally stable.The bearings of the kiln trucks are mounted on theshaft as far as its shoulder by means of a punching capand fastened securely with a shaft end washer andscrew. They have a loose fit in the housing bore of theFAG series housing SUB6208. Two bolts attach thehousings to the frame of the trucks. Strips insertedbetween housing and frame compensate for any differencesin height due to warping of the truck frame.Machining tolerancesShaft: bearing seat j6.Housing: the diameter of bearing seat is between0.5 mm and 0.8 mm larger than the bearing O.D.SealingHeat-resistant aramide stuffing box packings seal thebearing area at the axle passage. The cover flange is alsoprovided with a heat-resistant seal.51: Kiln trucks for sand lime brick works73 FAG