- Bearing Design as Related to Maximum Loads , Speeds , and Operating Temperatures

This paper outlines briefly a method suggested as a basis for journal-bearing design more especially for applications where the loads and speeds are variable and may reach relatively high values. This method is based upon two primary considerations; first, that the bearing shall operate in the region of stable lubrication, and second, that the operating temperature of the bearing shall not exceed some fixed value. Equations are derived for the rate of heat generation and for the rate of heat dissipation in terms of factors of construction and operation. Equating the rates of heat generation and dissipation yields an approximate relation between the construction and operation factors and the rise in temperature of a bearing above its surroundings when operating in the region of stable lubrication. The product of the maximum allowable pressures and speeds at which a bearing will operate under the conditions prescribed for safety is obtained by substituting in the above relation permissible values for the temperature rise and the generalized operating variable ZN/ P, where Z is the viscosity of the oil, N the speed of the journal, and P the bearing pressure. In a numerical example to illustrate the application of the method, individual values for the maximum permissible pressure and speed for a given bearing when using a given lubricant are obtained from the equation for the product of the speed and pressure and the minimum permissible value of ZN/P for stable lubrication. I. II. III. IV. V. VI. VII. VIII. CONTENTS Page Introduction ____ _____________ ____ _________________________ __ __ 457 Heat generated in bearing ____ _____ ___________________ __ _____ ___ _ 459 Heat dissipated ________ _____________ __ ___ ____ __ ________________ 459 Application to design _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ 461 ~~~f~~~~~~~~~~e:~~= = ===== = ========= = ======================== !~l Symbols ___ _________ ________ __ _____ ____ __ ___ __ __ ______________ 465 References ______ _________ ________ ______ __ ____ ___ ______________ 465