The Ball Roller – An Efficient Solution for Rotary Axes

Schaeffler Group Industrial has developed an efficient bearing concept for rotary axes. Based on the new “ball roller”, the special advantages of this solution lie in a significantly simplified adjacent structure and excellent transferability of bearing running accuracy to the rotary axis module, which is achieved thanks to a preloaded compact bearing support with single-piece bearing rings. The kinematic characteristics of the ball roller bearing also enable high limiting speeds while offering low friction and demand-oriented rigidity.


Ball roller offers numerous advantages

The innovation is based on a double-row angular contact thrust ball roller bearing in O-arrangement with novel rolling elements. All areas of the conventional rolling element “ball” that are not under load are removed, which means that 15 percent of the ball diameter is cut off on both sides of the ball. The result is the so-called ball roller, being 30 percent narrower and correspondingly lighter than a true ball. A bearing equipped with ball rollers has the same functionality and accuracy as a ball bearing. Various applications, e.g. in automotive and precision engineering, already benefit from the advantages offered by ball rollers, which include less space requirement, less weight, larger grease reservoir and higher load ratings.

Simpler, longer-lived and more cost-effective

In machine tool applications these characteristics offer advantages that increase the efficiency of the overall system:


The simplified adjacent structure results in reduced manufacturing costs: Due to the axial displacement of the bearing rings relative to each other, the bearing can be simply bolted to planed surfaces. Moreover, high-precision bearing seatings that support the bearing along the entire height are not required thanks to the rigid bearing design.

Mounting becomes simpler and faster: The single-piece bearing rings ensure improved transfer of the bearing’s running accuracy to the machine assembly. Moreover, a rolling bearing transportation safety device needed to hold split bearing rings together is not required. Mounting errors are thus avoided.

An increase in service life is achieved: The larger grease reservoir permits e.g. extended relubrication intervals and even maintenance-free operation in some applications. This is also supported by sealing gap systems on both sides that reliably retain the lubricant inside the bearing even at high speeds.

Pilot applications as from 2010

The double-row angular contact thrust ball roller bearing has already proved its functionality in the scope of the development project. Starting with bore diameter size 325 mm, the speed strength during continuous operation as well as the bearing behavior under load were tested under realistic operation cycles. Under all conditions, the tests of the prototypes were so positive that the extensive validation process will be continued with optimized and near-series prototypes. First pilot applications are scheduled to commence at the beginning of 2010. Potential initial users are still being sought.

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