6.8 Flashcards
what is a bearing
a machine element that constrains relative motion
what are the 2 key functions of bearings
reduce friction and keep things where they should be
what are the 2 groups of bearings
plain bearing that has no moving part and rolling element bearing that has rolling components
what are the 2 sub divisions of bearings
ball and roller bearings
what are the 2 characteristics of a good bearing
must be made of a strong material and the parts must be held in a position with very close tolerances
what are the 2 different types of forces that a bearing can be subject to
axial/thrust load acting along the supported shaft
radial/journal load acting at a right angle to the shaft
what type of load is a plain bearing usually designed to take
radial loads
when are plain bearings used
when the loads are relatively light and there is relatively constant motion
what are the advantages of anti friction bearings
very low starting friction, carry heavy loads, suitable for reversing or oscillating movement, run cooler than plain bearings
what are the 5 basic types of anti friction bearings
tapered, needle, ball, spherical and cylindrical
what does an anti friction bearing usually consist of
outer and inner raceway, a rolling element and usually a rolling element cage
what is the distinction between ball and roller bearings
ball bearings are suitable for high rotational speeds and roller bearings are used if the stresses are too severe for ball bearings
what is the reason why ball bearings aren’t good for oscillating loads
because they have a small contact point which means that all the stress would be concentrated on a tiny area
what is the main use for needle roller bearings
for high radial load capacity
what feature allows spherical roller bearings to allow minor angular displacements
self aligning feature
