Did you know that the waviness of
bearing balls and bearing races surfaces is one of the reasons for bearing noise and vibrations?
One interesting atypical uses for bearing balls is at San Francisco International Airport. The building is supported by 267 columns, each of which rests on a steel ball with a diameter of 5 feet (1.5 m). The ball sits in a concave foundation. If an earthquake occurs, the ground can move up to 20 inches (0.51 m) in any direction, as the columns roll on their bases. This is an effective way to separate the building from the movement of the ground. After the earthquake has ended, the columns are re-centered on their bases by the force of gravity.
09-03-2009, 11:28 AM
Little Known Fact #42532 
