TABLE OF CONTENTS We use the term bearing here in its most general sense. Whenever two parts have relative motion, they constitute a bearing by definition, regardless of their shape or configuration. Usually, lubrication is needed in any bearing to reduce friction and remove heat. Bearings may roll or slide or do both simultaneously. Thus, a cam-follower joint fits this definition of bearing, whether a flat-faced follower sliding against a cam or a roller follower rolling against a cam with a small amount of slip. The design and/or selection of bearings to support the camshaft will not be addressed here. See reference [3] for information on that topic.
Lubrication theory for surfaces in relative motion is extremely complex mathematically. Solutions to the partial differential equations that govern the behavior are based on simplifying assumptions that yield only approximate solutions. This chapter does not attempt to present a complete discussion or explanation of all the complicated phenomena of dynamic lubrication, as that is far beyond the scope of this text. Rather an introductory discussion of a few of the common cases encountered in machine design is presented. Boundary, hydrostatic, hydrodynamic, and elastohydrodynamic lubrication are introduced and described, and the theory for the last two conditions is discussed without presentation of complete derivations of the governing equations, due to space limitations.
Such topics as squeeze-film theory are not addressed at all, nor are the issues of lubricant supply to, and heat transfer from, the cam-follower joint. Derivations of the governing equations are...
