FUNDAMENTALS OF LUBRICATIONELLIS, E.G.
1967 Industrial Lubrication and Tribology
doi: 10.1108/eb052844
A series of articles dealing, in as simple a way as possible, with the basic facts of lubrication, lubricants, their selection and prescription, specification, application, and testing. This series is primarily intended for students, engineering personnel who may be unfamiliar with certain aspects and others who, one way or another, are interested in this important subject.
Solution of Problems Involving Grease Flow in Straight Pipe or TubingRein, S.W.; Brehmer, J.R.; Gesdorf, E.J.; Wegmann, J.
1967 Industrial Lubrication and Tribology
doi: 10.1108/eb052845
A SIMPLE method for solving problems involving steady flow of grease in pipes or tubing is being developed by the NLGI Subcommittee on Grease Dispensing in Central Systems. The method, based largely on a 1964 NLGI Annual Meeting paper, uses a graphical presentation of the Poiseuille equation for laminar flow. For this purpose, the Subcommittee has prepared charts that are direct reading in pressure drop and flow rate for pipe and tubing sizes commonly used in centralised systems and in transfer of grease from one point to another. The user of the charts must know the apparent viscosity characteristics of the particular grease of interest to him. When these data are plotted on the proposed NLGI chart as lines of shear stress vs. shear rate at constant temperature, various types of flow problems can be solved by drawing a few straight lines on the chart. Since the apparent viscosity is equal to the shear stress divided by the shear rate, the shear stress is found by multiplying each apparent viscosity value by its corresponding shear rate.
The Use of Depolymerised Natural Rubber as an Additive for Lubricating OilsWest, G.H.
1967 Industrial Lubrication and Tribology
doi: 10.1108/eb052846
Solutions of three types of depolymerised natural rubber were prepared using several lubricating oils as solvents. The zero shear viscosities of these solutions were measured over the range 3595C. employing a Ferranti concentric cylinder viscometer and it was found that the temperature dependence of the zero shear viscosity could be represented by a W.L.F. type relation. On this basis the variable parameter Ts in the W.L.F. relation was adopted as a suitable means of representing viscosity change with temperature. The experimental results showed that higher molecular weight, linear, depolymerised rubber was most effective in reducing the temperature change of viscosity of the base oil. The nature of the lubricating oil was found to be critical in this respect, only oils with an appreciable naphthenic content displaying improved temperature characteristics on addition of rubber.