Extended load capacity benefits to rolling stock Ultra-high performance Mancrodur bearings for railway applications
2017-10-04 | Frenchs Forest
Precision bearing manufacturer Schaeffler is extending into heavy rail the applications of its high-performance bearings made from proprietary Mancrodur rolling bearing steel, in combination with carbonitriding case hardening process.
Schaeffler Australia says its new High-Capacity TAROL Class K (HCT-K) tapered roller bearings for heavy rail traffic build on the success of its Mancrodur bearings that are already proving successful in wind turbines that are subjected to high loads, as well as in steel mills.
Compared with standard materials, Mancrodur's load-carrying capacity is approximately 30% higher. As a result, the nominal rating life of Mancrodur is more than twice as long. Increased load capacities and a substantially lower total cost of ownership (TCO) result from the greater surface hardness but, critically, also combined with improved ductility, says Schaeffler Australia.
Mancrodur bearings have been proved during extensive application in arduous operating conditions. “Even when subjected to extreme loads and shocks, this bearing consistently demonstrates its high-performance capabilities,” says Alexander Kabe, Project Manager High Capacity TAROL at Schaeffler. “Compared to the case hardening steel that is typically used in these applications, we are seeing significant performance gains with bearings made from Mancrodur.”
To help rail operators immediately achieve significant gains in the operating life of their fleets and to substantially lower their total cost of ownership (TCO), existing AAR Class K journals can easily be re-placed with Schaeffler's new HCT-K package bearing units.
Greater surface hardness, with improved ductility
Combining a high-performance steel with carbonitriding results in the highest load-carrying capacity for a given design envelope. From a materials-engineering perspective, this means this development represents the current state-of-the-art art with respect to bearing performance and efficiency.
Carbonitriding generates fine carbides and carbonitrides that are evenly distributed throughout the material. This results in a raceway surface that is harder and more resistant to wear. In addition, the heat treatment process increases the ductility of the raceway surface. Consequently, the material is less sensitive to contamination-induced overrolling.
In summary, compared to conventional materials and case hardening, Mancrodur with carbonitriding produces a material with high surface hardness and increased ductility. But only the combination of these two characteristics result in a significant increase in fatigue life.
TAROL bearing assembly: designed for heavy freight rail traffic
In addition to the new material, Schaeffler development engineers have added a number of other features to ensure that the HCT-K bearings can reliably handle millions of kilometres of use in heavy goods traffic.
These innovations include an inner ring that is heat stabilised up to 200-degrees C; a cage made from glass fibre-reinforced polyamide; and a bearing assembly that is fitted with extremely low-friction cartridge seals. To aid in providing an automated mounting process that is both reliable and efficient, the bearing also features a support ring.
Publisher: Schaeffler Australia Pty Ltd
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