The 2:1 Ratio is a geometric relationship which describes the allowable working space of plain bearings. It is the “Binding Ratio”, which is officially defined as the maximum ratio of moment arm distance to bearing length that will not bind (prevent motion). Since the 2:1 Ratio was first introduced to the marketplace by PBC Linear (originally Pacific Bearing Company) in the 1990’s, it has been quickly adapted by most self-lubricating, linear plain bearing manufacturers as one of the guiding principles regarding their use.
When a force is applied to a bearing at some distance away from the center of the bearing, a moment force is created. In order to resist the moment, two resulting forces are created at each end of the bearing. When these resulting forces are multiplied by the Coefficient of Friction, a drag force is created. At some point the drag force will surpass the drive force and motion will cease.
Within the Demystifying the 2:1 Ratio and the Stick-Slip Phenomenon white paper, we explain the importance of the 2:1 ratio as well as practical complications, limitations & troubleshooting. After reading this white paper, you should have a clearer understanding of the mathematics behind the 2:1 rule and a better comprehension of how to implement it.
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