Study on the friction in the tripod type couplings with external contacts

One of the basic criteria which is influencing the choosing process of a tripod coupling in a mechanical transmission is the friction. Due to their, construction the elements being in contact between the driver and the driven elements, are suppose to be optimized; this optimization it could be according to the shape or/and according to the materials. In the paper there are performed tests for the case of the line type contacts between the driver and the driven elements, in analogy with the tripod coupling with the cylinder on cylinder contacts. There are studied two cases: steel pin on steel disk and steel pin on PA66 polyamide type contacts. The test are performed for a set of rotational speeds of 500, 1000, 2000 and 3000 rpm and a set of normal forces as 3, 5, 7 and 9 N, in non-lubricated conditions. There are identified conclusions regarding the friction coefficient evolution and values in the case of steel on steel and steel on PA66 polyamide type contacts. (paper)