Techno Linear Motion Catalog24Technical InformationPlain bearings rarely ever carry more than 3000 psi.Another way of determining a bearings load capacity is through maximum PV factor. This is the value ofpressure on the bearing (psi) times the shaft speed (feet/min).If the PV value for the application is less than the maximum PV value for the bearingconsidered, and if the application pressure load does not exceed the compressivestrength of the bearing material, and if the application speed does not exceed themaximum permissible speed of the bearing considered, then the bearing consideredmay well serve the application.Ball Bearing Selection: The nature of the application load must be known and compared to the loadcarrying capability of the considered bearing. Combination loads should be converted into a single equivalentradial or thrust load using manufacturers equations to size the application requirement. Regarding speedrequirements, tolerance grade, lubrication, retainer design and bearing seal type must be considered, andthe maximum application speed must not exceed the maximum allowable bearing speed. A useful guide forball bearing selection is to consider the DN value (speed value) of the bearing. The DN value is the productof the bore size (mm) and the shaft speed (rpm). This quantity will suggest the type of lubrication andtolerance grade required. Use for the ball bearing type include applications involving shafts that may beslightly misaligned.Linear Ball Bearing Selection: This selection is generally based on speed and load requirements.Understanding the orientation and magnitude of the application loads on the bearing is of paramountimportance. Most manufacturers and suppliers of such bearings will include information regarding the loadcapabilities with respect to load orientation, as shown below.Roller Bearing Selection: Load, speed, and shaft alignment are the most important features to considerwhen selecting roller bearings. It is suggested that, in the case of needle bearings, the shaft parallelism beless than 0.0003" for the entire length of the bearing section. Further, the shaft should be round to within0.0002" or to within half the shaft tolerance.FZFAFY1.00.90.80.70.70.80.91.0FYXFZAF80°60°40°20°0°20°40°60°80°Force on Single BearingForce on Double Bearing