EHL Bearing Rig

Ball on Disc EHD lubrication apparatus

This apparatus is used to generate a single EHD lubricated contact. A rubber ball is supported on rollers and hydraulically loaded onto the underside of a steel disc. The ball is rotated at constant speed by an electric motor through a gear box and quill shaft. The Perspex disc is held stationary such that the ball is completely sliding against the underside of the disc. The ball-disc contact is flooded with a mineral oil, which is entrained into the contact to form an EHD film. A focused transducer is mounted above the contact in a water bath. The transducer is positioned directly above the contact region and at a distance such that the wave is focused on the ball-disc interface.

A schematic is shown below.


  • Load: 0 - 60 N
  • Maximum Hertzian pressure: 0 - 0.8 GPa (steel on glass)
  • Rolling speed: 0 - 2500 rpm (+/- 1%)
  • Slide/Roll Ratio: - 0.08 ± 0.1
  • Bulk oil temperature: 20 - 200 0C