Spherical roller bearings are double-row, self-containing units that comprise solid outer rings with a concave raceway, solid inner rings and barrel rollers with cages.
球面滚子轴承是双列，自我包含的单位，包括坚实的外圈与凹面滚，固体和内圈与辊每桶笼。
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There are also two roller straightening machine, relying on two rollers (Concave Intermediate, hyperbolic roll) the perspective of the different changes in the diameter of the material straightening.