M., Aroudj1,F., Inel22023-05-222023-05-222019-06-01M. Aroudj1, F. Inel2. INFLUENCE OF COEFFICIENT OF FRICTION ON THE PERFORMANCE OF PARALLEL GEARS. Journal of Fundamental and sciences. vol.11, no 3. june 2019. Faculty of exact sciences. university of el oued. [visited in 01/09/2019. available from [copy the link here]http://dspace.univ-eloued.dz/handle/123456789/23794articalGears performance is a very essential value that concluded the success of our system so researchers have worked hard to find mathematical relationships to calculate performance. Between these relationships we have the J.F. Debongnie method and the f.VILLE and VELEX method. In this work the yield of the parallel gears was calculated with the change of the modulus and the number of teeth using the J.F. Debongnie method and comparing them with the f.VILLE and VELEX method and associating them with the experimental results to be studied which is more close to the experimental results and the effect of the parameters selected in each method. After the comparison we found that the coefficient of friction the greatest impact on the performance whenever the lack of friction coefficient the greater the performance and the values of the J.F. Debongnie method higher than the values of the f.VILLE and VELEX method of the effect of the loss factor because it also affects the performance the greater the coefficient of loss whenever the performance.engear; performance; coefficient of friction; rotation speed; comparisonArticle