An experimental investigation was conducted to measure the friction forces between a vane tip and cam-ring in oil vane pumps. The incentive of this work is to study the effect of important parameters on the friction coefficient between a vane tip and cam-ring. Such parameters are relative speed between the vane tip and cam-ring, normal vane force, pressure difference between the two sides of the vane, and coating of the vane tip. A comparison was performed between five different (Physical Vapor Deposition) PVD-coated vane tips and the normal vane without coating. To satisfy
such requirements a special test rig was designed and constructed in the lab. The results show that the effect of the vane force and the pressure difference between the two sides of the vane are very small compared to the relative speed. The coating material shows no significant effect on the friction force in vane pumps. Therefore the wear properties of the coating materials should be considered in future studies. For friction measurements in oil vane pumps a simple test rig design with no pressure difference between the two sides of the vane is proposed.



Keywords: vane pump, friction, PVD, hydraulic, power steering, coating