Development of next-generation long-life bearing (NK bearing)
JTEKT Corporation has developed a next generation long-life bearing (NK bearing) for the use in harsh conditions mainly on agricultural and construction machinery. Through the optimization of material components and heat treatment conditions, we have succeeded in achieving further long life with improved robustness.
As such, JTEKT contributes to customers’ vehicle reliability improvement and maintenance manhour reduction, as well as the promotion of autonomous driving of agricultural and construction machinery and other machinery/vehicles.
* NK is the abbreviation for “new advanced knowledge”.
Application example: Tapered roller bearing
1. Background of development
Bearings used under harsh conditions such as on agricultural and construction machinery are required to have high robustness, and as such, JTEKT has been continuously developing and launching long-life bearings (such as KE bearing and SH bearing) on the market that satisfy the demand of high robustness. However, since the development of vehicles that require autonomous driving such as unmanned dump trucks and tractors is recently making progress in the agricultural and construction machinery industries, a bearing failure during the autonomous driving could be a severe problem. Furthermore, the demand for life cycle cost reduction and overhaul period extension are also increasing, so the expectations toward longer life and higher robustness are growing.
In response, JTEKT has developed a further long life bearing through the materials and heat treatment that have new concepts in order to achieve long life and high robustness. We will contribute to the customers’ vehicle reliability improvement, maintenance manhour reduction, and size reduction through this development.
2. Features of the developed product
Bearing damages are broadly divided into subsurface-initiated flaking and peeling. For agricultural and construction machinery bearings, improvement of durability against subsurface-initiated flaking as well as peeling initiated from brinelling under contaminated oil is an effective method.
(1)Structural toughening through the optimization of material components and heat treatment conditions
(2)High hardness of race surface resulting from precipitation of fine precipitates
(3)Fatigue strength increasing through securing the appropriate volume fraction of retained austenite (retained γ)
Flaking types and countermeasure
Development concept of long life material
Life test result of NK bearing in contaminated oil