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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.
A ball bearing. A bearing is a machine element that constrains relative motion to only the desired motion and reduces friction between moving parts.The design of the bearing may, for example, provide for free linear movement of the moving part or for free rotation around a fixed axis; or, it may prevent a motion by controlling the vectors of normal forces that bear on the moving parts.
The two surfaces do not touch, thus avoiding the problems of friction, wear, particulates, and lubricant handling associated with conventional bearings, and air bearings offer distinct advantages in precision positioning, such as lacking backlash and static friction, as well as in high-speed applications. [1]
Flexure bearings can give very low friction and also give very predictable friction. Many other bearings rely on sliding or rolling motions (rolling-element bearings), which are necessarily uneven because the bearing surfaces are never perfectly flat. A flexure bearing operates by bending of materials, which causes motion at microscopic level ...
Friction disc shock absorbers or André Hartford dampers were an early form of shock absorber or damper used for car suspension. They were commonly used in the 1930s but were considered obsolete post-war. [1] Compared to modern shock absorbers friction dampers only provided limited shock absorption but served mainly to damp down oscillation.
Fluid bearings generally have very low friction—far better than mechanical bearings. One source of friction in a fluid bearing is the viscosity of the fluid leading to dynamic friction that increases with speed, but static friction is typically negligible. Hydrostatic gas bearings are among the lowest friction bearings even at very high speeds.
A starting point for solving contact problems is to understand the effect of a "point-load" applied to an isotropic, homogeneous, and linear elastic half-plane, shown in the figure to the right. The problem may be either plane stress or plane strain. This is a boundary value problem of linear elasticity subject to the traction boundary conditions:
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] In locomotive and railroad car applications a journal bearing specifically referred to the plain bearing once used at the ends of the axles of railroad wheel sets, enclosed by axleboxes (also called journal ...