STUDY OF THE BEARING FRICTION INSIDE ON A MOBILE COUPLING JOINT

The mobile couplings are used in movement and torque transmission between two main shafts usually and have a wide application in transportation and machining systems. These mobile coupling must undertake the shafts misalignments that could appear, usually in the transversal plane and in the longitudinal plane. The friction which appears in coupling’s joints between the involved parts has an important influence on their dynamic behaviour, wear and lifetime. A solution to reduce the friction inside the mobile coupling is to place bearings in joints. The paper presents some general aspects on mobile tripod couplings and following this, using the inside relative movement in joints between parts and corresponding adequate bearing, the friction coefficient is studied. There are considered two cases for the studied radial ball bearings: a sealed one and a non-sealed one. The measurements are accomplished by using a tribometer for different radial loadings and rotational speeds of the inner ring of the bearings. In the final part of the paper, the results present the exploitation conditions of the bearings which assure small frictional loses. According to the obtained results, in order to gain small frictional loses, the mobile tripod coupling with external contacts are suitable to be used in the case of high loads, with small influences on the frictional behaviour of the rotational speeds.