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The SATISFACTORY LUBRICATION OF Diesel engines presents some of the most difficult problems encountered by oil technologists. This is especially true of large marine engines, where, due to low speeds and high loads, it is difficult to establish fluid film lubrication. Cylinder lubrication is particularly difficult due to the high temperatures encountered. This problem is more difficult in two‐stroke engines than in four‐stroke engines as, in the former, there is no non‐working stroke during which it is easier to form an oil film on the cylinder walls. Pressure‐charged two‐stroke engines are the most difficult of all to lubricate satisfactorily. The problem is aggravated in engines operating on residual fuel due to the high sulphur content increasing corrosive wear, and to the abrasive ash forming constituents present in such fuels. In addition, the contaminating influences of partially burnt products of combustion on the crankcase oil have to be considered. The ever‐present risk of water leakage into the crankcase oil, either from condensation, or from leakage of the cooling system, influences and often restricts the use of otherwise beneficial additives.

The low‐ and medium‐speed diesel engine design changes that have taken place to date, and are predicted to continue for the foreseeable future, present the marine diesel lubricant with a difficult environment which is expected to become more severe with respect to both wear and cleanliness performance, on account of increasing specific power output and wider use of lower grade residual fuels. This article describes in some detail the main in‐house laboratory rig and engine techniques and procedures which have been developed by the Authors' company for assessing the important aspect of wear control; it highlights the special techniques used during shipboard testing for determining cylinder liner and piston ring wear and shows that the results from field testing correlate with those obtained from the in‐house tests used to develop the latest generation of superior quality marine diesel lubricants.

Part One which appeared in our March issue dealt with Cylinder Lubrication and Wear and referred to Corrosive and Abrasive Wear and the Effects of Sulphur Compounds. This is a further extract from Mr. Clark's book on The Lubrication of Marine Machinery which will be published later this year.

The purpose of this paper is to develop a good calculation model to accurately predict the lubrication characteristic of main bearings of diesel engine and improve the service life.

Based on the coupling of the whole flexible engine block and the flexible crankshaft reduced by the Component Mode Synthesis (CMS) method, considering mass-conserving boundary conditions, the average flow model equation and Greenwood/Tripp asperity contact theory, an elastohydrodynamic (EHD)-mixed lubrication model of the main bearings for the diesel engine is developed and researched with the finite volume method and the finite element method.

Obviously, the mixed lubrication of bearings is normal, while full hydrodynamic lubrication is transient. The results show that under the whole flexible block model, maximum oil film pressure, maximum asperity contact pressure and radial shell deformation decrease, while minimum oil film thickness increases. Oil flow over edge decreases, and so does friction loss. Therefore, coordination deformation ability of whole engine block is favorable to mean load. In the whole block model, friction contact happens on both upper shell and lower shell positions. In addition, average oil film fill ratio at the key position becomes smaller in the whole engine block model, and consequently increases the chances of cavitations erosion more. So, wearing resistance of both upper and lower shells and anti-cavitations erosion ability must be enhanced simultaneously.

Based on the coupling of the whole flexible engine block and the flexible crankshaft reduced by the CMS method, considering mass-conserving boundary conditions, the average flow model equation and Greenwood/Tripp asperity contact theory, an EHD-mixed lubrication model of the main bearings for the diesel engine is built, which can predict the lubrication of journal bearings more accurately.

The above is the title of a paper by A. J. S. Baker and R. T. Davies (Esso Research Ltd.) presented to The Institute of Petroleum on 13th November in London. They pointed out the need for a suitable engine to test lubricating oils for marine diesel engine cylinder use. A two cylinder Bolnes engine was used having a 7.5 in. bore and 13.8 in. stroke, run under test conditions of 37.5 bhp/cylinder and 430 r.p.m. Lubricant was delivered to the working cylinders by sight feed lubricator, two feeds per cylinder discharging through open‐ended quills into an oil distribution groove in the liner below the scavenge ports. The test fuel had a sulphur content of 3.74%. The first test procedure consisted of a continuous period of 500 hr. operation, with cylinder oil fed at the rate of 1 g/bph/hr.—a rate recommended by the engine maker. Wear rates were higher than those obtained on engines at sea, but they provided a correct reflection of field performance.

In a paper to The Institute of Marine Engineers in London on January 29th, entitled Recent Development of the M.A.N. Marine Diesel Engine, Prof. Dr. Ing. E. Sorenson (Director in Charge of research and development, M.A.N.) and Dr. Ing. F. Schmidt (Engineer in charge of the design of large two‐cycle engines, M.A.N.) gave some information concerning the lubrication of these large engines. In connection with cyclinder lubrication, they said :—

A RECENT paper given to The Institute of Marine Engineers by Comm. K. I. Short, O.B.E., D.S.C., R.N., was concerned with operational experiences with medium speed Diesel engines and referred to several instances in which lubrication design could be improved. His first comments referred to lubricating oil pumps. Instances were quoted in which in order to avoid an unnecessary ‘extra’ the electrically driven system was adopted with the lubricating oil fed from essential services. Lack of electrical power or reduction of oil pressure shut down the engine but in practice there have been a series of incidents involving loss of pressure and failure to shut down the engine causing bearing damage. The author believed that the failures reported are enough to demand engine driven primary lubricating oil pumps as a prudent precaution, and especially in non‐reversing engines.

THE Engineering, Marine, Welding and Nuclear Energy Exhibition opens at Olympia on April 16th and runs until April 30. It is open from 10 a.m. to 6 p.m. each day (except Sundays), with the exception of April 27th, 28th, and 29th, when it remains open until 8 p.m. Price of admission is 3s. There are well over 500 stands and of these between 60 and 70 are showing products that should be of interest to most readers of Scientific Lubrication, since they concern some type of lubrication equipment. Amongst these are the following, and the illustrations reproduced here concern items which will be exhibited on the stands. Items in bold type describe new products or products being exhibited for the first time.

NEW LABORATORIES for additive testing, for general lubricants testing, and even for motor oils testing, are increasing in number all over the world, but the new laboratory opened on April 9th at the Royal Dutch/Shell Laboratory in Amsterdam will be concerned only with research and development work on lubricants for large, low‐speed marine diesel engines. It will be marine engines and their oils with which they will be concerned, but we have little doubt that a lot of work done here will provide valuable information also for other large diesel engine installation in various industrial fields.