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Wheels with Asanti 28 in (710 mm) rims on a police Hummer H2 car. The wheel size is the size designation of a wheel given by its diameter, width, and offset. The diameter of the wheel is the diameter of the cylindrical surface on which the tire bead rides. The width is the inside distance between the bead seat faces.
P – these tires are for a passenger vehicle. However 'P' denotes P metric size load and speed rating changes for P tire & non-P tires; 195 – the nominal width of the tire is approximately 195 mm at the widest point; 55 – indicates that the height of the sidewall of the tire is 55% of the width (107 mm) R – this is a radial tire
As an example of development, the Chrysler 277" polyspheric V8, first introduced in 1956, was gradually increased in size by bore and stroke to 326" by 1959, then received a drastic make-over in 1964 to conventional "wedge" combustion chambers, then modified again for stud-mounted rocker arms, and finally underwent an even greater re-design to ...
Tapered roller bearings were a breakthrough at the end of the 19th century because bearings used in wheel axles had not changed much since ancient times. They consisted of a cylindrical seat on the frame and part of the axle enclosed in a case or box that held a lubricant.
For a bearing where average of outer diameter of bearing and diameter of axle hole is 50 mm, and that is rotating at 3000 RPM, recommended dynamic viscosity is 12 mm 2 /s. [7] Note that dynamic viscosity of oil varies strongly with temperature: a temperature increase of 50–70 °C causes the viscosity to decrease by factor 10. [7]
BMX 3-Piece bottom brackets typically use a spindle either 19 mm or 19.05 mm (3/4″), 22 mm or 22.2 mm (7/8″), or 24 mm in diameter. The majority of newer or Asian parts are made to metric round numbers, and mixes of metric and non-metric (e.g. 19 mm and 19.05 mm) spindles and bearings may not be compatible, and can result in stuck parts.
Although bearings tend to wear out with use, designers can make tradeoffs of bearing size and cost versus lifetime. A bearing can last indefinitely—longer than the rest of the machine—if it is kept cool, clean, lubricated, is run within the rated load, and if the bearing materials are sufficiently free of microscopic defects.
Railroads normally use roller bearings which are either cylindrical (Russia) [63] or tapered (United States). [64] The specific rolling resistance in bearings varies with both wheel loading and speed. [65] Wheel bearing rolling resistance is lowest with high axle loads and intermediate speeds of 60–80 km/h with a Crr of 0.00013 (axle load of ...