OutlineBearingsComparing Rolling to JournalPowerPoint PresentationRolling Element BearingsBall BearingsRoller BearingsRolling Element ComparisonsRolling Element AnalysisSlide 10Slide 11Bearing Selection, P 10-26,27OutlineHydrodynamic/Journal/Sleeve BearingsRolling-Element Bearingstypesselection of roller bearingsBearingsall bearings are of course only necessary evils, contributing nothing to the product or function of the machine; and any virtues they can have are only of a negative order. Their merits consist in absorbing as little power as possible, wearing out as slowly as possible, occupying as little space as possible, and costing as little as possible(Michell, 1929)Comparing Rolling to JournalRolling Bearing are better because:low starting and good operating frictionradial and thrust loadsno self-excited instabilitiesless space axiallycan seal lubricant in bearingJournal Bearings are better because:fatigue failure not a problemless space radiallyless noisemore tolerant to misalignmentless expensive, except for oiling systemless operating frictiondeep groove ballfull journalpg. 654 in NortonReprinted From: "Design Data" Teague & Dunn, Machine Elements See http://www.engineersedge.com/bearing_application.htmRolling Element BearingsBall Bearingsgood for smaller sizes, lighter loadsRoller Bearingsgood for larger sizes, heavier loadshandle shock and impact loading wellPlainTaperedSphericalRolling Element ComparisonsFigure 10-21, Pg. 658 in NortonRolling Element AnalysisLoad RatingCalculate Plookup C, C0 in tablecalculate for a specific number of cyclesRating Life, L10life at which 10% of bearings have failedin millions of revolutions or in hoursEquivalent load for combined conditionsneeded when axial and thrust loads are presentVariable loadingBearing Selection, P 10-26,27Get tangential load on Gear 2 from equal & opposite torquesGet radial loads using radial load factorGet bearing reactions in x-dir from gear loads in x-z plane onlyGet bearing reactions in y-dir from gear loads in y-z plane onlyGet total vector load at each bearing (sqrt of sum of squares)Calculate needed minimum C, use Fig
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