The admissible values for the same combination of two materials, such as Bronze/Steel, varies according to the author ofthe document (see references [2], [4], [6]). Also the method and precise conditions of the tests differs between them and in some cases is unknown. CETIM has thus manufactured three disc/roller simulators for testing combinations of materials used in worm gears, The fatigue curves obtained will be introduced later in the
analytical calculation methods for load capacities [3], [8], [9]. For each combination of materials tested it was decided to metallurgically analyse the structure of the different bronze types. Also the cracks within simulated test rollers were observed to try and explain the fatigue phenomenon of contact pressure on the bronze surface.