{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,4]],"date-time":"2026-05-04T08:02:46Z","timestamp":1777881766704,"version":"3.51.4"},"reference-count":28,"publisher":"SAGE Publications","issue":"3","license":[{"start":{"date-parts":[[2007,3,1]],"date-time":"2007-03-01T00:00:00Z","timestamp":1172707200000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.sagepub.com\/page\/policies\/text-and-data-mining-license"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology"],"published-print":{"date-parts":[[2007,3,1]]},"abstract":"<jats:p>This work compares the friction between two contacting discs with the friction between gear teeth, using a mixed film lubrication model developed for the evaluation of contact pressure and shear stress fields [5]. Such model is used to analyse twin-disc contacts with smooth surfaces and gear teeth contacts with rough surfaces, both lubricated with an additive-free ISO VG 150 mineral oil.<\/jats:p>\n                  <jats:p>Experimental lubricant traction curves [4], measured in a twin-disc machine under full film elastohydrodynamic (EHD) lubrication (\u039b &gt; 2), were used to evaluate the lubricant rheological parameters, taking into account the surface roughness of the contacting discs. Experimental power loss measurements, made during gear efficiency tests performed in a Forschungsstelle f\u00fcr Zahnr\u00e4der und Getriebebau (FZG) test rig [4], were used to evaluate the average friction coefficient between gear teeth along the meshing line, considering the surface roughness of the tooth flanks.<\/jats:p>\n                  <jats:p>The experimental friction coefficients between gear teeth were compared with predictions obtained using three different approaches: (a) values directly extrapolated from the experimental lubricant traction curves, (b) values calculated using a full film EHD lubrication model, considering surface roughness, and (c) values from a mixed film lubrication model. These analysis were performed at three different scales, from the roughness peaks (inside contact) to the entire gear meshing line, passing through the contact dimension.<\/jats:p>\n                  <jats:p>The results obtained show that the mixed film lubrication model is able to evaluate accurately the friction between gear teeth in power transmission equipment whatever the lubrication regime, boundary, mixed or full film.<\/jats:p>","DOI":"10.1243\/13506501jet257","type":"journal-article","created":{"date-parts":[[2007,5,15]],"date-time":"2007-05-15T09:39:20Z","timestamp":1179221960000},"page":"399-411","source":"Crossref","is-referenced-by-count":49,"title":["Coefficient of friction in mixed film lubrication: Gears versus twin-discs"],"prefix":"10.1177","volume":"221","author":[{"given":"J","family":"Castro","sequence":"first","affiliation":[{"name":"Departamento de Engenharia Mec\u00e2nica, Instituto Superior de Engenharia do Porto, Porto, Portugal"}]},{"given":"J","family":"Seabra","sequence":"additional","affiliation":[{"name":"Faculdade de Engenharia, da Universidade do Porto, Porto, Portugal"}]}],"member":"179","published-online":{"date-parts":[[2007,3,1]]},"reference":[{"key":"bibr1-13506501JET257","first-page":"651","volume-title":"In Proceedings of the 30th Leeds-Lyon Symposium on","author":"Sottomayor A."},{"key":"bibr2-13506501JET257","unstructured":"Winter H., Michaelis K. FZG gear test rig - description and test possibilities. Co-ordinate European Council Second International Symposium on The Performance Evaluation of Automotive Fuels and Lubricants, Wolfsburg, West Germany, 5-7 June 1985, pp. 29\u201342."},{"key":"bibr3-13506501JET257","unstructured":"Castro J. Gripagem de engrenagens FZG lubrificadas com \u00f3leos base. Novos crit\u00e9rios de gripagem globais e locais. PhD Thesis, Demegi, FEUP, November 2004."},{"key":"bibr4-13506501JET257","doi-asserted-by":"publisher","DOI":"10.1016\/S0167-8922(01)80156-5"},{"key":"bibr5-13506501JET257","first-page":"525","volume-title":"Tribology and interface engineering","author":"Castro J."},{"key":"bibr6-13506501JET257","unstructured":"H\u00f6hn B.R., Michaelis K., Vollmer T. Thermal rating of gear drives balance between power loss and heat dissipation. AGMA Technical Paper, October 1996, 96FTM8, 12 pp."},{"key":"bibr7-13506501JET257","doi-asserted-by":"crossref","unstructured":"Sottomayor A., Seabra J., Campos A., Ferreira L. Thermal and non-Newtonian analysis of EHD line contacts. In Proceedings of the 21st Leeds-Lyon Symposium on Tribology, Tribology Series 30, Lubricants and Lubrication, 1995, pp. 229\u2013247.","DOI":"10.1016\/S0167-8922(08)70633-3"},{"key":"bibr8-13506501JET257","first-page":"129","volume-title":"Boundary and mixed lubrication: science and applications","author":"Robbe-Valoire F."},{"key":"bibr9-13506501JET257","first-page":"37","volume-title":"Boundary and mixed lubrication: science and applications","author":"Williams J. A.","year":"2002"},{"key":"bibr10-13506501JET257","volume-title":"Life ratings for modern rolling bearings: a design guide for the application of international standard ISO 281\/2","author":"ASME Tribology Division Technical Committee.","year":"2003"},{"key":"bibr11-13506501JET257","doi-asserted-by":"publisher","DOI":"10.1016\/S0301-679X(00)00024-4"},{"key":"bibr12-13506501JET257","volume-title":"Mechanical engineering series","author":"Hamrock B. J.","year":"1994"},{"key":"bibr13-13506501JET257","doi-asserted-by":"publisher","DOI":"10.1016\/S0043-1648(98)00221-X"},{"key":"bibr14-13506501JET257","doi-asserted-by":"publisher","DOI":"10.1080\/10402000108982471"},{"key":"bibr15-13506501JET257","doi-asserted-by":"publisher","DOI":"10.1007\/978-94-010-0736-8_54"},{"key":"bibr16-13506501JET257","unstructured":"Winter H., Michaelis K. Scoring load capacity of gears lubricated with EP-oils. AGMA Fall Technical Meeting, Montreal, Canada, October 1983."},{"key":"bibr17-13506501JET257","doi-asserted-by":"publisher","DOI":"10.1115\/1.2928879"},{"key":"bibr18-13506501JET257","unstructured":"Barral R. Mod\u00e9lisation du champ de pression, du film de lubrifiant et des contraintes tangentielles dans un contact EHD rugueux. Premi\u00e8res \u00e9tudes des contraintes engendr\u00e9es dans les massifs. Rapport technique T03, Etude du pitting de mat\u00e9rieux d'engrenages de boites de vitesses manuelles - approche th\u00e9orique et pratique, RVBV 10 (RENAULT - DIMAT) e 98.21.01 (INEGI - CETRIB), 1999."},{"key":"bibr19-13506501JET257","volume-title":"Elastohydrodynamic lubrication","author":"Dowson D."},{"key":"bibr20-13506501JET257","volume-title":"Ellis Horwood series in mechanical engineering","author":"Gohar R.","year":"1988"},{"key":"bibr21-13506501JET257","doi-asserted-by":"publisher","DOI":"10.1115\/1.3453342"},{"key":"bibr22-13506501JET257","unstructured":"Tevaarwerk J. L. Traction calculations using the shear plane hypothesis. In Proceeding of the 6th Leeds-Lyon Symposium on Tribology, Lyon, September 1979, pp. 201\u2013213."},{"key":"bibr23-13506501JET257","doi-asserted-by":"publisher","DOI":"10.1201\/9780849377877.ch29"},{"key":"bibr24-13506501JET257","first-page":"19","volume-title":"Boundary and mixed lubrication: science and applications","author":"Cheng H."},{"key":"bibr25-13506501JET257","doi-asserted-by":"publisher","DOI":"10.1080\/10402000308982626"},{"key":"bibr26-13506501JET257","doi-asserted-by":"publisher","DOI":"10.1115\/1.3261472"},{"key":"bibr27-13506501JET257","unstructured":"Seabra J. Influence de l'ondulation des surfaces sur le comportement des contacts Hertziens secs ou lubrif\u00edes. PhD Thesis, no 8ISAL0018, INSA, Lyon, 1988."},{"key":"bibr28-13506501JET257","unstructured":"Campos A. Determina\u00e7\u00e3o da geometria do filme lubrificante, da distribui\u00e7\u00e3o de press\u00e3o e das tens\u00f1oes de corte num contacto elastohidrodin\u00e2 mico. Aplica\u00e7\u00e3o a rolamentos de rolos. MSc Thesis, Demegi, FEUP, 1994."}],"container-title":["Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/journals.sagepub.com\/doi\/pdf\/10.1243\/13506501JET257","content-type":"application\/pdf","content-version":"vor","intended-application":"text-mining"},{"URL":"https:\/\/journals.sagepub.com\/doi\/pdf\/10.1243\/13506501JET257","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,5,1]],"date-time":"2026-05-01T00:52:29Z","timestamp":1777596749000},"score":1,"resource":{"primary":{"URL":"https:\/\/journals.sagepub.com\/doi\/10.1243\/13506501JET257"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2007,3,1]]},"references-count":28,"journal-issue":{"issue":"3","published-print":{"date-parts":[[2007,3,1]]}},"alternative-id":["10.1243\/13506501JET257"],"URL":"https:\/\/doi.org\/10.1243\/13506501jet257","relation":{},"ISSN":["1350-6501","2041-305X"],"issn-type":[{"value":"1350-6501","type":"print"},{"value":"2041-305X","type":"electronic"}],"subject":[],"published":{"date-parts":[[2007,3,1]]}}}