NEEDLE ROLLER BEARINGS CONSTRUCTION The prefi x letters in metric series drawn cup bearing designations denote whether the bearings are made with a full complement of needle rollers or caged needle rollers. The use of a full complement of needle rollers is indicated by the prefi x code letters BM, BHM, or YM and for use of caged needle rollers by the prefi x code letters HK, BKM, BTM, BHTM, BSM or BK. The outer ring, in the form of a cup, is accurately drawn and no subsequent machining is performed. Drawn cup needle roller bearings of series HK, BKM, BTM, BHTM, BSM, BM, BHM and YM have open ends. The HK and BKM series also are available with one seal, HK RS, and with two seals, HK 2RS and BKM UU. The stamped lip of a drawn cup needle roller bearing of series HK RS is at the seal end. Drawn cup needle roller bearings of series BK is closed at one end. They are used for shaft-end mounting. The open end is typically not sealed. The one-piece steel cage used in HK, BKM and BK series drawn cup bearings is designed to provide rigidity and minimize wear. This cage design separates the needle roller guiding and retention functions. DRAWN CUP NEEDLE ROLLER BEARINGS METRIC SERIES When a rolling bearing is needed for a compact and economic design and where it is not practical to harden and grind the housing bore, or where the housing materials are of low rigidity such as cast iron, aluminum or even plastics – drawn cup needle roller bearings should be considered. REFERENCE STANDARDS ARE: • ISO 3245 – rolling bearings – needle roller bearings, drawn cup, without inner ring, boundary dimensions and tolerances. • ANSI/ABMA 18.1 – needle roller bearings – radial, metric design. • DIN 618 – needle roller bearings with cage – drawn cups with open end, drawn cup with closed end. • JIS B 1536 – rolling bearings – needle roller bearings – boundary dimensions and tolerances. Before selecting specifi c drawn cup needle roller bearings, please review the engineering section of this catalog. Drawn cup needle roller bearing, caged, open ends Drawn cup needle roller bearing, caged, open ends Drawn cup needle roller bearing, caged, closed end Drawn cup needle roller bearing, caged, open ends, sealed BKM, BSM, HK BTM, BHTM BK HK RS Drawn cup needle roller bearing, full complement, open ends Drawn cup needle roller bearing, caged, closed end, sealed Drawn cup needle roller bearing, caged, open ends, sealed Fig. B2-1. Types of metric series drawn cup needle roller bearings BM, BHM YM BK RS BKM...UU, HK .2RS B B-2-6 NEEDLE ROLLER BEARINGS