Techno Linear Motion Catalog20Technical InformationRacewaysFilling slotsRolling Element Bearings, or roller bearings, make up the bulk ofcommercially available and applied bearings. These types of bearingsrely on either balls or rollers to carry the load. The rolling motionproduces less friction than found in plain bearings. For this reason,roller bearings are also referred to as antifriction bearings. Both radialloads and thrust loads can be supported by this type of bearing.Lubrication is either permanently sealed in the bearing or is requiredduring operation. The largest causes of failure are either exceedingtemperature, load and speed limits, or providing insufficient lubricationduring operation. Since roller bearing applications often involve heavyloads and high speeds, failure can be catastrophic, extremely costlyand time consuming to repair. Usually there will be an increase in thesound of the balls or rollers in the raceways when approaching failure.There are many different configurations of roller element bearings, andsome are discussed in the following section.Radial Ball Bearingscome in two basic variations whichare called the Conrad type, or nonfilling slot, and themaximum capacity type, or filling slot. The Conrad type hasa deep, uninterrupted raceway in inner and outer rings. Thisdesign is capable of carrying heavy radial and moderate bi-directional thrust loads. The maximum capacity bearing hasmore balls than an equivalent sized Conrad type, thereforecarries a higher radial load. However, the filling slots requirethat the thrust loads be light and applied only in combinationwith a heavier radial load. If moderate thrust loads arepresent, the maximum type can be replaced by a doublerow Conrad type bearing. Selection of this type bearing isoutlined in the following section.Thrust Ball Bearingsare designed toprovide axial shaft location and supportthrust loads. Angular contact ballbearings support radial as well as thrustloads, and the ratio of permissible radialto thrust loads depends upon the angleof contact between the races and thebearing axis. Thrust ball bearings arecommonly used in linear motionsystems to support the drive screw.Conrad-type ball bearing, left, andmaximum-capacity (filling slot) type, rightFlat-race, flat-seat thrust ball bearing, A, andgrooved-race, flat-seat thrust ball bearing, BAligning, double-acting, grooved-racethrust ball bearingABBanded thrust ball bearing, A, andaligning, single-acting, grooved-racethrust ball bearing, BBAOuter raceRolling elementInnerRaceROLLING ELEMENT