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Many Tribology Group publications are Open Access thanks to funding from the EPSRC.

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  • Journal article
    Cann PM, Spikes HA, 1987,

    The influence of lubricant on temperature generated in elasto-hydrodynamic contacts.

    , Tribology Series, Vol: 12, Pages: 183-192, ISSN: 0167-8922

    Direct measurement of temperatures generated in concentrated contacts by infra-red (IR) radiometry can be used to explore the rheological properties of lubricants under elastohydrodynamic (EHD) conditions. This paper describes the influence of lubricant composition on thermal effects in EHD and attempts to relate rheological characteristics of the fluids to the temperature produced. The lubricants have been chosen to provide a range of rheological and chemical properties. They include synthetic hydrocarbons, polyglycols, perfluorethers, and a traction fluid. An emission technique similar to that employed by Winer and coworkers (1976) has been used to measure the surface temperature distribution within an EHD contact. Significant differences have been found between the surface temperature response of these fluids. The role of lubricant rheology in determining temperature with EHD contacts is discussed together with the implications of such measurement in the study of the traction response of lubricants.
  • Journal article
    Spikes HA, 1987,

    Wear and fatigue problems in connection with water‐based hydraulic fluids

    , Journal of Synthetic Lubrication, Vol: 4, Pages: 115-135, ISSN: 0265-6582

    Water‐containing fluids are widely used in hydraulic applications where there is a significant risk of fire, as in underground mining and metal working applications. Although primarily intended as power transmitting media, hydraulic fluids need to possess a modicum of lubricating ability to limit wear, seizure and contact fatigue of pumps and other rubbing parts. Unfortunately water‐based hydraulic fluids generally show significantly poorer wear and rolling‐contact fatigue performance than mineral or synthetic oil‐based fluids of similar viscosity and this means that pumping equipment usually has to be derated when used with water‐based fluids. This paper examines the poor wear and fatigue performance of water‐based fluids and discusses, in some detail, the origins of this poor performance and the ways it can be mitigated. Copyright © 1987 John Wiley & Sons, Ltd
  • Conference paper
    Spikes HA, 1986,

    HELICOPTER LUBRICATION.

    , Pages: 59-74

    Helicopter systems, and in particular helicopter transmissions, pose severe problems of lubrication and these are reflected in shorter overhaul periods and lower reliability than other, comparable systems in fixed wing aircraft. Many of these problems may be met by the introduction of new materials, such as ceramic engine bearings, flexible rotor parts, new gear steels and synthetic transmission oils. One stumbling block should, however be recognised. Helicopters, though important and irreplaceable for some applications, are not produced in large numbers and the cost of applying new technology can be prohibitive if a significant amount of development work needs to be done. Even the validation of a new material is enormously expensive, involving as it must, helicopter flying time. It is these costs, rather than the merits or availability of new materials and technologies that may be the main barrier to improvements in helicopter lubrication.
  • Journal article
    Spikes HA, Olver AV, Macpherson PB, 1986,

    Wear in rolling contacts

    , Wear, Vol: 112, Pages: 121-144, ISSN: 0043-1648
  • Journal article
    Spikes HA, 1986,

    Future helicopter transmission oils

    , Journal of Synthetic Lubrication, Vol: 3, Pages: 181-208, ISSN: 0265-6582

    <jats:title>Abstract</jats:title><jats:p>For many years helicopter transmissions have shown low reliability relative to planned overhaul lives and to other comparable lubricated systems. Reasons for this include the extremely wide range of conditions encountered by the lubricant in helicopter transmissions and also the requirement that, in many cases, the oil be common to both transmission and gas turbine engines.</jats:p><jats:p>Recently acquired understanding of lubrication mechanisms shows that potential exists both for improved performance and for the ability to cater for higher temperatures by the development of new helicopter transmission oils based on synthetic lubricants.</jats:p><jats:p>This paper discusses the particular lubricating problems associated with helicopter transmission lubrication and describes test methods and formulation approaches to improving such lubricants.</jats:p>
  • Journal article
    Danping W, Spikes HA, 1986,

    The lubricity of diesel fuels

    , Wear, Vol: 111, Pages: 217-235, ISSN: 0043-1648
  • Journal article
    WEBSTER MN, SAYLES RS, 1986,

    A NUMERICAL-MODEL FOR THE ELASTIC FRICTIONLESS CONTACT OF REAL ROUGH SURFACES

    , JOURNAL OF TRIBOLOGY-TRANSACTIONS OF THE ASME, Vol: 108, Pages: 314-320, ISSN: 0742-4787
  • Journal article
    WEBSTER MN, WEST MA, SAYLES RS, 1986,

    A METHOD OF 3-DIMENSIONAL TOPOGRAPHY MEASUREMENT AND ANALYSIS ON ARCUATE SURFACES

    , WEAR, Vol: 109, Pages: 385-399, ISSN: 0043-1648
  • Journal article
    Olver AV, Spikes HA, Bower AF, Johnson KLet al., 1986,

    The residual stress distribution in a plastically deformed model asperity

    , Wear, Vol: 107, Pages: 151-174, ISSN: 0043-1648
  • Journal article
    Lacey IN, Kelsall GH, Spikes HA, Macpherson PBet al., 1986,

    Thick Antiwear Films in Elastohydrodynamic Contacts. Part I: Film Growth in Rolling/Sliding EHD Contacts

    , A S L E Transactions, Vol: 29, Pages: 299-305, ISSN: 0569-8197
  • Journal article
    Lacey IN, Kelsall GH, Spikes HA, Macpherson PBet al., 1986,

    Thick Antiwear Films in Elastohydrodynamic Contacts. Part II: Chemical Nature of the Deposited Films

    , A S L E Transactions, Vol: 29, Pages: 306-311, ISSN: 0569-8197
  • Conference paper
    Olver AV, Spikes HA, MacPherson PB, 1985,

    WEAR IN ROLLING CONTACTS.

    , Pages: 254-272, ISSN: 0192-4990

    Unexpectedly high, uniform rates of wear occur from time to time in concentrated, lubricated, rolling contacts having low slide-roll ratios. Such wear can occur under quite mild conditions and this poses a significant practical problem, especially in gears. This phenomenon of high wear rate at low slide-roll ratio has been reproduced consistently and studied in the laboratory using a disc machine. The outcome of this study is reported. It is shown that the wear is caused by plastic deformation, fatigue cracking, ductile extrusion and fracture on a scale associated with asperity contact.
  • Journal article
    Spikes HA, Cann P, Caporiccio G, 1984,

    Elastohydrodynamic film thickness measurements of perfluoropolyether fluids

    , Journal of Synthetic Lubrication, Vol: 1, Pages: 73-86, ISSN: 0265-6582
  • Conference paper
    Cann P, Spikes H, 1984,

    DETERMINATION OF OIL FILMS ON LUBRICATED SURFACES.

    , Pages: 79-82

    It is often important in Tribology to be able to determine the thickness of lubricant on surfaces before and after rubbing. This paper describes a method of measuring oil film thickness in the range 20-1000nm using reflection infrared spectroscopy. Results for some practical applications are included and their implications are discussed.
  • Journal article
    Wan GTY, Kenny P, Spikes HA, 1984,

    Elastohydrodynamic properties of water-based fire-resistant hydraulic fluids

    , Tribology International, Vol: 17, Pages: 309-315, ISSN: 0301-679X

    The elastohydrodynamic (ehd) lubricating properties of commercial fire-resistant hydraulic fluids in rolling point contacts are described. Earlier work is reviewed and new work presented on water-in-oil and oil-in-water emulsions. It is shown that in general, elastohydrodynamic film thicknesses of water-in-oil emulsions are close to those of their base oils. For very fine particle size emulsions, however, thicker films are observed. Commercial oil-in-water emulsions in fully flooded conditions have not been found to give measurable elastohydrodynamic films. However, when the emulsions are destabilized, a localized pool of oil collects in the contact zone which enables ehd films to form, though these films do not survive very high rolling speeds. Polyglycol solutions give low ehd film thicknesses, approximately one third those of mineral oils of corresponding viscosity. This can be attributed to the low pressure-viscosity coefficient of these solutions. © 1984.
  • Journal article
    Wan GTY, Spikes HA, 1984,

    The elastohydrodynamic lubricating properties of water-polyglycol fire-resistant fluids

    , ASLE Transactions, Vol: 27, Pages: 366-372, ISSN: 0569-8197

    Commercial aqueous polyglycol hydraulic fluids are found to give very low elastohydrodynamic film thicknesses. By studying mixtures of polyglycol, monoglycol, and water, it is shown that this is became the pressure-viscosity coefficients of polyglycol and monoglycol fall very sharply when they are mixed together or when water is added. Over the polyglycol, monoglycol, water mixture range, pressure-viscosity coefficient appears to be inversely related to free volume. Presented as an American Society of Lubrication Engineers paper at the ASLE/ASME Lubrication Conference in Hartford, Connecticut, October 18–20, 1983. © 1984 Taylor & Francis Group, LLC.
  • Journal article
    CANN P, CAMERON A, 1984,

    STUDIES OF THICK BOUNDARY LUBRICATION - INFLUENCE OF ZD DP AND OXIDIZED HEXADECANE

    , TRIBOLOGY INTERNATIONAL, Vol: 17, Pages: 205-208, ISSN: 0301-679X
  • Journal article
    Cann P, Spikes HA, Cameron A, 1983,

    Thick Film Formation by Zinc Dialkyldithiophosphates

    , A S L E Transactions, Vol: 26, Pages: 48-52, ISSN: 0569-8197
  • Journal article
    SAYLES RS, MOSS TR, DANIELS BK, 1983,

    DISCRIMINANT FUNCTION-ANALYSIS OF TURBOGENERATOR DATA

    , RELIABILITY ENGINEERING & SYSTEM SAFETY, Vol: 6, Pages: 83-102, ISSN: 0951-8320
  • Journal article
    SAYLES RS, 1983,

    THE USE OF DISCRIMINANT FUNCTION TECHNIQUES IN RELIABILITY ASSESSMENT AND DATA CLASSIFICATION

    , RELIABILITY ENGINEERING & SYSTEM SAFETY, Vol: 6, Pages: 103-124, ISSN: 0951-8320
  • Journal article
    HARRIES CJ, WEBSTER M, SAYLES RS, MACPHERSON PBet al., 1983,

    BI-MODAL FAILURE MECHANISMS IN TRIBOLOGICAL COMPONENTS

    , RELIABILITY ENGINEERING & SYSTEM SAFETY, Vol: 4, Pages: 169-180, ISSN: 0951-8320
  • Journal article
    Stinton HC, Spikes HA, Cameron A, 1982,

    A study of friction polymer formation

    , ASLE Transactions, Vol: 25, Pages: 355-360, ISSN: 0569-8197

    Surfactant solutions in hexadecane have been studied to assess their capabilities in forming friction polymer. Only alcohols form adherent films, resistant to simple washing, on rubbing surfaces. There is no evidence of polymer formation on rubbed surfaces, even with mixtures of diacids and diols. © 1982 Taylor & Francis Group, LLC.
  • Journal article
    Spikes HA, Hammond CJ, 1981,

    The Elastohydrodynamic Film Thicknesses of Binary Ester-Ether Mixtures

    , A S L E Transactions, Vol: 24, Pages: 542-548, ISSN: 0569-8197
  • Journal article
    SAYLES RS, DESILVA GMS, LEATHER JA, ANDERSON JC, MACPHERSON PBet al., 1981,

    ELASTIC CONFORMITY IN HERTZIAN CONTACTS

    , TRIBOLOGY INTERNATIONAL, Vol: 14, Pages: 315-322, ISSN: 0301-679X
  • Journal article
    SAYLES RS, POON SY, 1981,

    SURFACE-TOPOGRAPHY AND ROLLING ELEMENT VIBRATION

    , PRECISION ENGINEERING-JOURNAL OF THE AMERICAN SOCIETY FOR PRECISION ENGINEERING, Vol: 3, Pages: 137-144, ISSN: 0141-6359
  • Journal article
    HILEY RW, SPIKES HA, CAMERON A, 1981,

    POLYSULFIDES AS EXTREME-PRESSURE LUBRICANT ADDITIVES

    , LUBRICATION ENGINEERING, Vol: 37, Pages: 732-737, ISSN: 0024-7154
  • Journal article
    Newley RA, Spikes HA, Macpherson PB, 1980,

    Oxidative Wear in Lubricated Contact

    , Journal of Lubrication Technology, Vol: 102, Pages: 539-544, ISSN: 0022-2305

    <jats:p>Lubricant antioxidant additives are known to reduce fretting wear. Wear tests have been carried out in association with chemical analyses of the test lubricant to elucidate the mechanism of oxidative wear. It is shown that the rate of wear is not directly related to the concentration in the lubricant of either acids or peroxides. It is proposed that the metal is oxidized by reacting with peroxy radicals which form as intermediates as the lubricant is oxidized. The reduction of wear in the presence of antioxidants is a result of the elimination of these radicals by the additive.</jats:p>
  • Journal article
    THOMAS TR, SAYLES RS, HASLOCK I, 1980,

    HUMAN JOINT PERFORMANCE AND THE ROUGHNESS OF ARTICULAR-CARTILAGE

    , JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME, Vol: 102, Pages: 50-56, ISSN: 0148-0731
  • Journal article
    Hamaguchi H, Spikes HA, Cameron A, 1977,

    Elastohydrodynamic properties of water in oil emulsions

    , Wear, Vol: 43, Pages: 17-24, ISSN: 0043-1648
  • Journal article
    , 1974,

    A comparison of adsorption and boundary lubricant failure

    , Proceedings of the Royal Society of London. A. Mathematical and Physical Sciences, Vol: 336, Pages: 407-419, ISSN: 0080-4630

    <jats:p>A comparison has been made between the reversible adsorption and the friction-reducing properties of long-chain fatty amines on stainless steel. This has shown that adsorption and lubricant failure depend on concentration of amine and temperature in a similar way. Breakdown of lubrication may therefore be associated with reversible desorption of amines from steel surfaces. Measurement of the adsorption properties of the fatty amines indicates a lowering of the isosteric heat of adsorption at low temperatures, which may result from ‘pre-freezing’ of the hydrocarbon solvent.</jats:p>
  • Journal article
    Spikes HA, Cameron A, 1974,

    Additive Interference in Dibenzyl Disulfide Extreme Pressure Lubrication

    , A S L E Transactions, Vol: 17, Pages: 283-289, ISSN: 0569-8197
  • Journal article
    Spikes HA, Cameron A, 1974,

    Scuffing as a Desorption Process—An Explanation of the Borsoff Effect

    , A S L E Transactions, Vol: 17, Pages: 92-96, ISSN: 0569-8197

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