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n. Abbr. bb
1. A friction-reducing bearing consisting essentially of a ring-shaped track containing freely revolving hard metal balls against which a rotating shaft or other part turns.
2. A hard ball used in such a bearing.
1. (Mechanical Engineering) a bearing consisting of a number of hard steel balls rolling between a metal sleeve fitted over the rotating shaft and an outer sleeve held in the bearing housing, so reducing friction between moving parts while providing support for the shaft
2. (Mechanical Engineering) a metal ball, esp one used in such a bearing
1. a bearing consisting of a number of hard balls running in grooves in the surfaces of two concentric rings, one of which is mounted on a rotating or oscillating shaft.
2. a ball so used.