# Outline Hydrodynamic/Journal/Sleeve Bearings Rolling-Element Bearings

## Presentation on theme: "Outline Hydrodynamic/Journal/Sleeve Bearings Rolling-Element Bearings"— Presentation transcript:

Outline Hydrodynamic/Journal/Sleeve Bearings Rolling-Element Bearings
types selection of roller bearings

all 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 Journal
Rolling Bearing are better because: low starting and good operating friction radial and thrust loads no self-excited instabilities less space axially can seal lubricant in bearing Journal Bearings are better because: fatigue failure not a problem less space radially less noise more tolerant to misalignment less expensive, except for oiling system less operating friction deep groove ball full journal pg. 654 in Norton

Rolling Element Bearings

Ball Bearings good for smaller sizes, lighter loads

Roller Bearings good for larger sizes, heavier loads

Rolling Element Comparisons
Figure 10-21, Pg. 658 in Norton Rolling Element Comparisons

Rolling Element Analysis
Load Rating Calculate P lookup C, C0 in table calculate for a specific number of cycles Rating Life, L10 life at which 10% of bearings have failed in millions of revolutions or in hours Equivalent load for combined conditions needed when axial and thrust loads are present Variable loading

Bearing Selection, P 10-26,27 Get tangential load on Gear 2 from equal & opposite torques Get radial loads using radial load factor Get bearing reactions in x-dir from gear loads in x-z plane only Get bearing reactions in y-dir from gear loads in y-z plane only Get total vector load at each bearing (sqrt of sum of squares) Calculate needed minimum C, use Fig 10-23