Outside the inner steel ring, are successively ranged the first layer of balls or rollers, freely rolling steel ring, the second layer of balls or rollers and outer steel ring. That is to say, between the inner and outer steel rings, there are two layers of balls or rollers and a sandwiched steel ring, and all these can reduce friction resistance through rolling. Compared with background technology, the present invention has high efficiency of reducing friction resistance and can be used in various machinery. |