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Super Long-Life Planetary Shaft for Automobile Transmissions
Tokyo, Japan, October 17, 2014 - NSK Ltd. (NSK; Headquarters: Tokyo, Japan; President and CEO: Norio Otsuka) today announced that it has developed a super long-life planetary shaft for use in planetary mechanisms* used in automobile automatic transmissions (AT), continuously variable transmissions (CVT), hybrid systems, etc.
NSK optimized the heat treatment process and materials in order to lengthen the life of the type of planetary shafts that are staked at both ends. As a result, the overall planetary mechanism can be smaller and lighter, contributing to improved fuel in automobiles.
NSK is targeting 2 billion yen in global sales for this product in 2018.
*Planetary mechanism: A mechanism that accelerates, decelerates and reverses the rotational force input from the engine by using a combination of the rotation and revolution of multiple gears.
Development Background
In recent years there has been an urgent need at a global level for higher efficiency in transmissions in order to meet the demand for better fuel efficiency in automobiles. In response to this need, the number of gears in transmissions is increasing, and transmissions are becoming more compact and lighter, while the friction loss of the lubrication inside transmissions is being reduced. There is even a demand for needle bearings, which are commonly used in planetary mechanisms, to be more compact and lighter.
Amidst this drive to make planetary mechanisms more compact, the use of the staking method on both ends of the planetary shaft for anchoring to the carrier is increasing.
Product Features
1. Use of staking on both ends (plastic forming) as an anchoring method
2. Longer life through new materials and heat treatment
NSK developed original material and optimized the heat treatment process to achieve longer life. Furthermore, application of induction hardening has proven effective in reducing the impact of increased hardness on both ends of the shaft, thereby making it possible to use staking (plastic forming) on both ends of the shaft, which in turn makes it possible to anchor the shaft to the carrier.
In this way, NSK has been able to maintain the same level of durability as its conventional long-life product (pin type) while also achieving a super-long-life of 2.5 times that of the long-life product.
In addition, if the product is designed to stay at the same life expectancy level, then it is possible to make it approximately 30% slimmer than the long-life product (staking type).
| Product Model | Inside Diameter | Outside Diameter | Thickness |
| 24184BK30+AH24184H NTN | 400 | 310 | |
| 23184BK+AH3184 NTN | 400 | 266 |