Jeweled bearings use a metal spindle with a jewel lined pivot hole (pictured below). They have been important in the manufacture of mechanical timepieces since the early 1700's. Their importance lies in the fact that they can be machined to very high accuracy, they have low and predictable friction, and their hardness gives them very low wear. They are known for operating in sealed environments for decades with no servicing.
With the advent of synthetic crystal manufacturing in the early 1900's jeweled bearings became the standard for every important bearing in mechanical timepieces. Every quality mechanical watch manufactured these days, for instance, has at least 17 jeweled bearings for the 'going train'.
My questions are:
- Are there any other common applications for jeweled bearings besides mechanical timepieces?
- If so, what are the largest jeweled bearings used for?