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To analyze the work principle and capacity of energy conversion in each segment of profile lines, the energy transfer from impeller to transmission medium is separated into head coefficient and load coefficient to analyze the energy transfer process. The concepts of airfoil lift coefficient and drag coefficient are used; the third manifestation of the Euler equations is used as well.

The numerical simulation of energy conversion mechanism based on load criteria of vane airfoil has been established in screw centrifugal pump to explain its energy conversion mechanism in an impeller. Upon this basis, the velocity and pressure along the entire blade are investigated through the numerical simulation of internal solid–liquid flow in the pump. The energy conversion process under load criteria in the blade airfoil has also been obtained.

The research suggests that the mathematical model of energy conversion mechanism based on the load criteria of the vane airfoil is reliable in the screw centrifugal pump. The screw centrifugal blade has twice or even several times the wrap angle than the ordinary centrifugal blade. It is a large wrap angle that forms the unique flow channel which lays the foundation for solid particles to pass smoothly and for soft energy conversion. At the same time, load distribution along the profile line on the long-screw centrifugal blade is an important factor affecting the energy conversion efficiency of the impeller.

The quantitative analysis method of energy in the screw centrifugal pump can help the pump designer improve certain features of the pump and shorten the research cycle.

FOR THE PURPOSE OF HANDLING HEAVY and light bunker fuel oil at Kuwait Harbour, five large pumps have recently been completed by Stothert and Pitt Limited at their Bath works. They are, in fact, the largest screw‐type pumps yet made by the company, having been called size 350, which is the measurement of their diameter over the screw threads in millimetres.

THE past two years have seen a notable increase in the number of services on aircraft for which some form of power is required. First, retractable undercarriages, followed by wing flaps, gun turrets, and automatic pilots, have demanded a light and compact source of power, capable of being transmitted to remote points on the machine. As suitable power units have become available, so have other applications presented themselves, with the consequent freeing of the pilot and crew from irksome manual effort.

This paper aims to revisit the preventive maintenance scheduling literature. The problem to be solved is the simultaneous scheduling of resource‐constrained preventive maintenance and operations. In particular, the expression that defines the period‐dependent cost function for a preventive maintenance scheduling activity is redefined. A case study is presented from the shipping industry.

In this paper a mathematical theory of differential calculus known as three‐dimensional wave equation is applied. The methodology involves transforming the preventive maintenance cost function that is expressed in terms of several variables into a more precise framework. The motivation for the work is the need to measure the total preventive maintenance scheduling cost more precisely than with the use of the existing linear cost structure.

In this paper the findings from the analysis carried out found evidence that validates the claim of the feasibility of analyzing preventive maintenance cost using the approach proposed.

The paper shows that, in practice, maintenance managers strive to reduce the cost of preventive maintenance activities in order to achieve low cost production of goods. This would encourage a high patronage of customers and prevent decisions being made on wrong data. The approach presented here aims at correcting this weakness by revealing a more precise and reliable method of preventive maintenance scheduling cost computation. This is a scientific tool that should be of immense benefit to maintenance planners, particularly those actively engaged in scheduling functions.

The work in this paper is new, since a novel framework is presented in a way that has not been documented earlier.

Hardsurfacing with Ni/Cr‐base alloys gives additional advantages in protection against corrosion and atmospheric and high‐temperature oxidation. The latter effects frequently contribute greatly to the rate of wear. The self‐fluxing characteristics of such boron‐containing alloys, coupled with a wide melting range, enables the coating of contoured surfaces and application by spraying and fusing. Using a bonding agent very thin protective coatings may be applied by furnace fusion.

This survey covers civil, electrical and electronics, energy, environment, general, materials, mechanical, and traffic and transportation engineering. Areas such as biomedical and chemical engineering will be dealt with in future issues. Readers may find that the classifications included in this survey are not mutually exclusive but do occasionally overlap with one another. For instance, the section on environmental engineering includes a review of a book on the environmental impact of nuclear power plants, which might as easily have been part of the section on energy technology. Before we go into a discussion of data bases and indexes, I would like to note in this introductory section some recent bibliographic aids published during the period surveyed. Most engineering libraries will find them very valuable in their reference and acquisition functions. Since normal review sources will cover these books, I am merely listing them below: Malinowski, Harold Robert, Richard A. Gray and Dorothy A. Gray. Science and Engineering Literature. 2d ed., Littleton, Colorado, Libraries Unlimited, 1976. 368p. LC 76–17794 ISBN 0–87287–098–7. $13.30; Mildren, K. W., ed. Use of Engineering Literature. Woburn, Mass., Butterworths, 1976. 621p. ISBN 0–408–70714–3. $37.95. Mount, Ellis. Guide to Basic Information Sources in Engineering. New York, Wiley, Halsted Press, 1976. 196p. LC 75–43261 ISBN 0–47070–15013–0. $11.95 and Guide to European Sources of Technical Information. 4th ed., edited by Ann Pernet. Guernsey, Eng., F. Hodgson, 1976. 415p. ISBN 0–85280–161–0. $52.00.

This study aims to solve the premature failure of the rubber stator due to wear, reduce the frictional resistance moment of the screw pump to solve the problem of a model of Daqing oilfield screw pump oil recovery system shutdown after the difficult start.

For the first time, the rotor surface of a screw pump was treated with dot-matrix texture to study the effect of dot matrix texture on the tribological performance of the stator-rotor friction subsets of screw pump. Reciprocating friction tests with different texture morphologies (S-shape, double tongue) and angular parameters (0°, 45° and 90°) were conducted at 10% of the texture area and pump silicone grease.

When point texture was added to the surface of the rotor sample, the friction coefficient and wear quantity of the sample were lower than those of the surface without texture treatment, and the double tongue 0° combination showed the best tribological properties. At this time, the average coefficient of friction and wear is reduced by 22.8% and 62%, 28.6% and 64.8%.

The introduction of texture can effectively improve the tribological performance of progressive screw pumps, and this paper provides important theoretical and experimental support for the design of progressive screw pumps in practical applications.

THE following description of the fuel supply systems of the BMW 132K and 132N, “Bramo” Fafnir 323 P‐1 and BMW 801 air‐cooled radial engines is based on the following reports supplied by the Ministry of Aircraft Production.

The rotor in screw motor is driven to rotate by highly pressure difference of drilling fluid (DF), while rotor drives drill bit to break rocks. DF works in the volume cavity (VC) which exists between the stator and rotor (SAR), these process realizes the conversion from hydraulic energy to mechanical energy finally. In order to assure seal performance and output power reliability of VC in common hypocycloid screw motor (CHSM), it’s essential to survey SAR end-face profile.

In this article, based on the internal and external cycloid method given for SAR end-face of φ172 7/8-head LZ type CHSM, the interference among SAR is established based on the meshing model through theoretical equilibrium method (TEM). Last, the reasonable design value of SAR interference in TEM is verified with the hydraulic parameters test results.

The profile optimization that top-root part of rotor end-face profiles is replaced by elliptical-circular arcs (ECA) makes the transition area of tooth-top and tooth-root connect smoother than before. The reasonable interference of SAR in TEM is almost 0.16mm~0.22mm to ensure better sealing performance. Through the hydraulic test, the interference positive fluctuation or the number of SAR head reduces increase (starting-pressure-drop) SPD while negative fluctuations by contraries. Meanwhile, DF penetration also decreases the revolution speed with the SAR interference decreases. The less SAR head revolution speed is always below the more with the constant driving power and DF hydraulic drop. Ultimately, decreasing in overall-efficiency occurs for larger fluctuation of interference or or less interference among SAR.

The line type optimization and analysis in TEM for CHSM improves the motor seal and output performance, also has important application values simultaneously.

ABOUT two years ago—early in 1928—rumours first began to circulate that the Packard Company had built a successful air‐cooled radial Diesel engine which had satisfactorily completed flight tests.