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The design of a plain bearing depends on the type of motion the bearing must provide. The three types of motions possible are: Journal (friction, radial or rotary) bearing: This is the most common type of plain bearing; it is simply a shaft rotating in a hole. [3]
An axlebox, also known as a journal box in North America, is the mechanical subassembly on each end of the axles under a railway wagon, coach or locomotive; it contains bearings and thus transfers the wagon, coach or locomotive weight to the wheels and rails; the bearing design is typically oil-bathed plain bearings on older rolling stock, or roller bearings on newer rolling stock.
For any given bearing, there is a value for indicated by C, for which the coefficient of friction is at a minimum. The bearing should not be operated at this value of bearing modulus, since a slight decrease in speed or a slight increase in pressure will make the part of a shaft or axle that rests on bearings operate in partial lubrication ...
S is the Sommerfeld Number or bearing characteristic number r is the shaft radius c is the radial clearance μ is the absolute viscosity of the lubricant N is the speed of the rotating shaft in rev/s P is the load per unit of projected bearing area. The second part of the equation is seen to be the Hersey number.
Some small single-cylinder engines have only one main bearing, [citation needed] in which case it must withstand the bending moment created by the offset distance from the connecting rod to the main bearing. When describing a crankshaft design, the number of main bearings is generally quoted, as the number of crank pins is determined by the ...
Hersey's original formula uses the rotational speed (revolutions per unit time) for N and the load per projected area (i.e. the product of a journal bearing's length and diameter) for P. Alternatively, the Hersey number is the dimensionless number obtained from the velocity (m/s) times the dynamic viscosity (Pa∙s = N∙s/m2), divided by the ...
The ABEC scale is designed to provide bearing manufacturers dimensional specifications that meet the standards of precision bearings in a specified class. The scale is also used by manufacturers who produce equipment that require bearings must also know the dimensional tolerances to design parts that will accommodate a bearing.
A foil bearing, also known as a foil-air bearing, is a type of air bearing. A shaft is supported by a compliant, spring-loaded foil journal lining. Once the shaft is spinning fast enough, the working fluid (usually air ) pushes the foil away from the shaft so that no contact occurs.