: A Textbook of Machine Design: Contents 1 Introduction 2 Engineering materials and their properties 3 Manufacturing considerations in machine. Veja grátis o arquivo A Textbook of Machine Design by AND J.K. GUPTA enviado para a disciplina de Elementos de Máquinas I Categoria: . A TEXTBOOK OF. (S.I. UNITS) [A Textbook for the Students of B.E. / , U.P.S.C. (Engg. Services); Section ‘B’ of A.M.I.E. (I)]. R.S. KHURMI J.K. GUPTA.
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It is denoted by h0 and occurs at the line of centres as shown in Fig. It is the temperature at which an oil gives off sufficient vapour to burn it continuously when ignited. A commonly used clearance in industrial machines is 0. However, space requirements, manufacturing, tolerances and shaft deflections are better met with a short bearing.
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Because of the side leakage of the lubricant from the bearing, the pressure in the film is atmospheric at the ends of the bearing. If the ratio of the length to the diameter of the journal i.
It is the minimum distance between the bearing and the journal, under complete lubrication condition. It the difference between the diameters of the bearing and the journal. Short and long bearing.
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It is the ratio of the eccentricity to the radial clearance. This is the region where the viscosity of the lubricant ceases to be a measure of friction characteristics but the oiliness of the lubricant is effective in preventing complete metal to metal contact and seizure of the parts.
The bearing should not be operated at this value of bearing modulus, because a slight decrease in speed or slight increase in pressure will break the oil film and make the journal to operate with metal to metal contact.
The following terms used in hydrodynamic journal bearing are important from the subject point of view: The density at any other temperature t may be obtained from the following relation, i. The diametral clearance c in a bearing should be small enough to produce the necessary velocity gradient, so that the pressure built up will support the load.
A Textbook of Machine Design by R.S.KHURMI AND J.K.GUPTA .0005
It is the lowest temperature at which an oil gives off sufficient vapour to support a momentary flash without actually setting fire to the oil when a flame is brought within 6 mm at the surface of the oil. It is the difference between the radii of the bearing and the journal. Also the small clearance has the advantage of decreasing side leakage. McKee in an actual test of friction is shown in Fig.
However, the allowance must be made for manu- facturing tolerances machinr the journal and bushing.
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Attitude or eccentricity ratio. This will result in high friction, wear and heating. The average pressure will be higher for a long bearing than for r.s.kgurmi short machinne square bearing. It has been shown by experiments that the coefficient of friction for a full lubricated journal bearing is a function of three variables, i.
Enviado por igualdi flag Denunciar. It is the ratio of the diametral clearance to the diameter of the journal.
When the length of the journal l is equal to the diameter of the journal dthen the bearing is called square bearing. Pour point or freezing point.
The thin film or boundary lubrication or imperfect lubrication exists between R and S on the curve. It is denoted by e. The term viscosity index is used to denote the degree of variation of viscosity with temperature. It is the temperature at which an oil will cease to flow when cooled.
Minimum desitn film thickness.