An experimental rig for testing bearings with different types of oil jet supplies has been used in neutron radiography and in positron emission tomography imaging. This rig had been manufactured from aluminium and steel.

A recent test was carried out of this rig on a thermal neutron beam. The rig was not being operated and it had been completely drained of oil. Some dried-out hydrocarbon material had remained deposited near the two jet feed pipes. A thermal neutron radiograph was taken of the dry rig following which a small quantity of water was poured into each of the two jet feed pipes and allowed to drain away. A second neutron radiograph shows that internal surfaces of the feed pipes in the region of the jets were wet with a water film. This demonstrates the sensitivity of the NR method for detecting hydrogenous materials even through thick metallic sections.


 

Neutron imaging of a bearing rig

We had also carried out PET imaging with this same test rig. Oil doped with Gallium-68 was injected in one or other of the jet inlet feeds whilst the bearing was being spun with an electric motor. The interest was to know how effective lubrication of the large bearing was if the oil was injected near to the ball race. For lubrication to be effective, positron activity should be seen on both sides of the bearing as was shown in the PET image.