Full Complement Bearings
Full complement ball bearings capitalise on the space usually occupied by the ball retainer, as removing the retainer enables additional balls to be fitted. This increase in ball complement allows for significant increases in bearing capacity in either axial or radial directions. Barden offers two basic designs of full complement bearings, each with different capabilities, limitations and fields of application:
Deep Groove Design
A filler notch bearing builds on existing deep groove bearing designs. Standard deep groove bearings are limited on the number of balls that can be fitted, effectively restricting the complement to 50% of the theoretical full complement. The introduction of a filler notch to both the inner and outer rings allows the remaining balls to be fitted.
The filler notch is ground into the ring so a dam is produced at the point of entry to the raceway. The dam, found on both rings, is calculated so that with the smallest ball and the maximum radial play, interference is maintained. After fitting the standard deep groove complement the notches are aligned and the balls pressed over the dams into the raceway.
The filler notch design bearing is primarily for use in applications where radial loads are dominant and the increased ball complements allow higher loads to be supported than in a standard caged deep groove bearing. Due to the introduction of a notch into each race on the same side, the filler notch design can be limited in its ability to carry axial load. For specific designs and applications the notch geometry can be optimised to carry an increased axial load in either one or both directions.
Angular Contact Design
In contrast to the filler notch design, the X205 builds on the angular contact bearing design. Again the retainer is removed from the bearing, generating space that can be occupied by additional balls. Since the usual ball complement for an angular contact bearing is higher than that of a deep groove bearing, the increase in capacity is not as high.
Standard angular contact components can be used and already incorporate a dam to retain the balls after assembly. The balls are carefully loaded into the deep groove race and are held in place by the relief of the angular contact ring. The application of heat to the outer ring causes expansion of the component, removing the interference between the balls and the dam. The rings to move into position and after the outer ring has cooled the balls are retained in the raceway.
X205 bearings also differ dramatically in their use, primarily being used in applications of high thrust loading. Radial load capacity of the bearing is greater than that of the original angular contact ball bearing, becoming limited by interaction of the contact ellipse with the dam.
With the retainer removed from the bearing the balls are no longer spaced apart and can make contact with each other. With the inner ring acting as a sun gear, each ball is driven in the same clockwise direction. At the points of contact the balls are travelling in opposing directions, leading to friction and wear. Due to the introduction of ball to ball friction the bearing torque is also increased. The use of ceramic balls can provide lower wear levels and reduced bearing friction/torque.
It is not recommended practice to use full complement X205 bearings in solidly preloaded systems.