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This paper aims to study a dynamic analysis of a double-helical geared rotor system with oil-film bearing.

A finite element model of a double-helical geared rotor system with oil-film bearing is developed, in which a rigid mass is used to represent the gear and the Timoshenko beam finite element represents the shaft; the equations of motion are obtained by applying Lagrange’s equation. Natural frequencies, Campbell diagram, lateral responses, axial responses, bearing stiffness coefficients, bearing damping coefficients and bearing force are investigated.

Natural frequencies and Campbell diagram of a double-helical geared rotor system with oil-film bearing are investigated. An increased helical angle enhanced the axial response of the system and reduced its lateral response. The distance between the node and bearing affected the lateral response magnitude on the node. The farther away the gear pair was from the central part of the shaft, the higher the system’s resonance frequency became. The different gear pair position has a significant influence on the bearing stiffness coefficient and bearing force, but it just has a little effect on the bearing damping coefficient.

The model of a double-helical geared rotor system with oil-film bearing is established in this paper. The dynamic characteristics of a double-helical geared rotor system with oil-film bearing are investigated. The numerical results of this study can be used as a reference for subsequent personnel research.

Although the dynamics characteristics of geared rotor bearing system have been reported in some literature, the dynamic analysis of a double-helical geared rotor-bearing system is still rarely investigated. This paper showed some novel results that lateral and axial response results are obtained by the different helical angle and different gear positions. In the future, it makes valuable contributions for further development of dynamic analysis of a double-helical geared rotor-bearing system.

AT THE INTERNATIONAL CONFERENCE ON GEARING arranged by the Institution of Mechanical Engineers in London from the 23rd to 25th September, a special session was set aside for the Discussion of Lubrication and the following papers were presented :—

SINCE so little information has been made available in this country with regard to Russian aero‐engines, it was thought worth‐while to attempt to compile a description of this engine, although it was first produced at least fifteen years ago. This description is necessarily incomplete and to some extent disjointed because most of it is based on references contained in the book Aero‐Engines—Design and Detail Calculations, edited by A. E. Zaikin, of the Joukowsky Military Aviation Academy of Kiev, and published in 1941 by the State Publishing House of the Defence Industry. This book was not intended to describe any one engine but rather, to indicate the merits and demerits of various components of many engines including English, American, French and German products. It is known that most of the aero‐engines produced in Russia are of foreign origin and for this reason it was assumed that interest would be taken in the AM.34 which does appear to be of Russian design.

FROM the very beginning of their career as aircraft engine builders in 1915, Messrs. Rolls‐Royce have held the view that any sacrifice of efficiency in the interests of expediency was not permissible. It was for this reason that water‐cooling was adopted from the outset and has been developed continuously up to the production of their latest “F” and “H” engines, which form the subject of this article.

The purpose of this paper is to explore the possibilities of improving the quality of existing maintenance task of the atomizer of milk powder manufacturing unit of a dairy plant. Looking to the past business volume and expected growth, the milk powder manufacturing unit forms a noticeable sector of processing plant. The lack of quality in maintenance standards leads to reliability losses of about 20–25% with low productivity and profit. Such facts and challenges of keeping the system in ready-state motivate a definite maintenance plan to be modeled based on a live failure analysis to be executed during shutdown or scheduled period.

The deliverables are achieved by collecting the historical failure data i.e. downtime and failure frequencies; from January 2020 to July 2020 at Dudhsagar dairy, Gujarat, India. Reliability modeling is done in a view to understand the failure pattern behavior of the milk powder manufacturing unit. The atomizer is discriminated as a critical component based on these data and their functional failures, failure causes, effects and repercussions of failures with existing control and maintenance practices has been modeled based on live shop-floor study. Scores are assigned on 1 to 10 levels by analyzing attributes effects from lowest to highest concern respectively for every modes of failure through realistic brain-storming among maintenance team by incorporating some advanced attributes like maintainability, economic safety, economic cost and spares with basic criteria in this study. The maintainability criticality index (MCI) is narrated by these score values through multi-attribute decision-making (MADM) based failure analysis models like Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS).

The primary findings of this research work are to propose improvements in the quality of the maintenance plan of critical component like; atomizer of a milk powder manufacturing unit which is commonly representing critical component in a major range of industrial processes. The case study recommended four silent maintenance strategies i.e. scheduled maintenance scheduled discard, scheduled failure finding and redesign as a qualified maintenance plan for the atomizer based on MCI and rankings of its potential failure causes. The results are helpful in upgrading quality standards for the maintenance activities of a process industry of alike or of dissimilar kinds in accordance with the failure analysis.

Originality mainly consists of investigating the scope of enhancing the existing maintenance practices through actual failure analysis with the help of TOPSIS. The criteria employed in this study are probability of chances of failure, degree of detectability and degree of severity as basic criteria along with some advanced criteria like; maintainability, spare parts, economic cost, economic safety are selected based on the outcome of shop-floor study and reliability modeling. The notable past failure statistics (downtime, frequency of failures) of a milk powder manufacturing unit were recorded and these data are analyzed based on reliability to extract an explicative component i.e. atomizer.

The metering pump is recognised as an efficient means of dosing or “injecting” predetermined quantities of liquid and semi‐solid materials into a processing stream. Originally designed for simple dosing applications, technological developments introduced in response to the ever‐changing demands of industry have made this a highly accurate item of processing equipment that is hard to surpass.

Part One in this series appeared in our January issue and dealt with fundamental factors and properties required by gear lubricants. Part Two in our February issue covered the lubrication of worm gear units. The next part will give details of gear manufacturers' recommendations and their formulae for arriving at the most suitable oil viscosity for lubrication of their respective gear units. Future parts will include full details of the causes and elimination of gear wear, fracture and breakdowns caused by incorrect lubrication or application of lubricants, and of course those troubles frequently and erroneously blamed on to the lubricant.

Stimulated by previous reference, which proposed making straight line of regression to test gear gravimetric wear loss sequence distribution, this paper aims to propose using straight line of regression to fit gear gravimetric wear loss sequence based on stationary random process suppose. Faced to that the stationary random sequence suppose had not been proved by previous reference, and that prediction did not present high precision, this paper proposes a method of fitting non-stationary random process probability distribution function.

Firstly, this paper proposes using weighted sum of Gauss items to fit zero-step approximate probability density. Secondly, for the beginning, this paper uses the method with few Gauss items under low precision. With the amount of points increasing, this paper uses more Gauss items under higher precision, and some Gauss items and some former points are deleted under precision condition. Thirdly, for particle swarm optimization with constraint problem, this paper proposed improved method, and the stop condition is under precision condition.

In experiment data analysis section, gear wear loss prediction is done by the method proposed by this paper. Compared with the method based on the stationary random sequence suppose by prediction relative error, the method proposed by this paper lowers the relative error whose absolute values are more than 5%, except when the current point sequence number is 2, and retains the relative error, whose absolute values are lower than 5%, still lower than 5%.

Finally, the method proposed by this paper based on non-stationary random sequence suppose is proved to be the better method in gear gravimetric wear loss prediction.

FORMED in 1927 by a group of engineers and first established in a small works in Staines, Middlesex, the business of the company had grown so much within eight years that more extensive premises were required. Accordingly, a factory was built at Staines which helped to meet the large demand for gear cutting machines and tools for military equipment that came with the Second World War. Prior to the War and as soon as possible afterwards, W E Sykes developed a considerable export trade as well as an increasing home market and by 1951, a large expansion was required. The original small premises became the Sykes Machine Tool Co, a leading importer of tools and equipment from Europe and the USA. The export trade of the main company was facilitated by the formation of subsidiaries in Canada and Australia and by the appointment of numerous established firms as agents.

MANY who realise the implications of White's book on The Organisation Man have probably closed it with the self‐satisfied reflection that ‘it can't happen here.’ That is the anodyne we generally swallow to protect us from disagreeable fears.