A study of bearing and its types conference Paper

5.1 Research and Development on The Tilting Pad Thrust Bearing 
In order to keep a machine workable for long periods, friction and wear of its parts must be kept low. It was in 
the 1880s when OIL FILM Lubrication was first observed and investigated during the experimental work of 
Beauchamp Tower with theoretical contributions from Osborn Reynolds.
The pivot pad bearing was invented by Anthony G. M. Michell in 1905 and independently by Albert Kingsbury 
in 1910 in a slightly different version. A G M Michell followed up, and made an important extension to, this 
initial work when he developed the mathematical basis for his revolutionary breakthrough in applying oil film 
lubrication to flat thrust faces. 
In 1905 Michell patented a type of bearing in which the load was carried upon the oil films generated by a series 
of pivoting white metal faced pads. The principle was applied to both thrust and journal bearings, and is now 
universally known as the MICHELL BEARING. 
 
VI. THE MICHELL PRINCIPLE 
There are two elements in a Michell Thrust Bearing- the rotating thrust collar and the pivoting thrust pads. 
These two elements never come in contact while the bearing is in operation; being forcibly separated and kept 
apart by tapered oil films, self generated from the normal oil supply. Figure 2b, illustrates how these 
indestructible pressure oil films are generated and maintained between the working surfaces of the thrust pads 
and collar. 
It is an important basic fact that the tapered pressure oil film or wedge of lubricant is self generated by the 
motion of the thrust collar and is not dependent on any extraneous pressure from an oil pump. All Michell thrust 
pads are designed and proportioned so that they tilt and generate a thick oil film to carry the thrust load. Figure 
3, shows an example of pressure distribution and typical oil flow lines across the face of a Michell thrust pad. 
With the working faces kept apart in this simple and well ordered manner, there is no metallic contact, no 
metallic friction, no wear and no renewal of parts – provided of course good uncontaminated oil is always 
present in sufficient volume at the thrust bearing.