Press Release

NSK Develops Shaft Seal Type Sealed Clean Ball Bearing for Transmission Applications

Smaller, Lighter and Less Friction Loss

Shaft Seal Type Sealed Clean Ball Bearing for Transmission Applications

Tokyo, Japan, July 3, 2013 – NSK Ltd. (NSK; Headquarters: Tokyo, Japan; President and CEO: Norio Otsuka) today announced that it has developed a shaft seal type sealed clean ball bearing for transmission applications such as manual transmissions (MT) and dual clutch transmissions (DCT). The new bearing helps reduce friction loss and enables more compact, lighter solutions.
NSK is targeting 1.8 billion yen in annual sales of this product in 2018, anticipating an increase in demand for MTs and DCTs in Europe and emerging markets.

Development Background

As demand for better fuel economy has increased in recent years, it has become more and more critical to improve the efficiency of transmissions designed for automobiles by making them more compact and lighter and reducing friction loss. This means that transmission shafts also have to be more compact, lighter and with less friction loss. However, in order to keep foreign objects (such as the abrasive powder generated when meshing with the gears) from penetrating the ball bearings used in MTs and DCTs, seals are required, resulting in the problem of friction loss due to the sliding movement of the seals. Also, the conventional shape of such seals requires spacers due to the abrasion caused by contact with surrounding parts, resulting in an increase in number of components.

Bearing Usage

Product Features

In response to these challenges, NSK has developed a shaft seal type sealed clean ball bearing that helps reduce friction loss and makes for smaller and lighter solutions for further improvement of transmission efficiency.

1. Half the friction loss
NSK developed a proprietary seal shape that maintains sealing performance while reducing contact force.* In doing so, bearing durability is maintained and sliding friction is cut in half, for improved transmission efficiency.
* Contact force: Tightening force of seal on the shaft. The higher the contact force, the higher the friction loss; the smaller the contact force, the lower the sealing performance.
2. More compact and lighter transmissions now possible
In optimizing the shape of the inner race, NSK was able to improve the permissible load in the axial direction by approximately 20% over the conventional product, making it possible to make the bearing even more compact. Also, in employing a shaft seal that directly slides on the outside diameter of the inner race, NSK has eliminated the need for a spacer, thus reducing the number of components needed.

NSK bearing products for transmissions such as its sealed clean ball bearings, which prevent the instruction of foreign objects, and its HTF ball bearings, which have improved resistance to foreign objects due to stronger materials, are being applied by a wide variety of automobile manufacturers throughout the world. NSK is committed to continuing to work on developing products that help automobile manufacturers reduce size, weight and torque for better fuel economy.

New Bearing Feature Shaft Seal
Shape of the New Shaft Seal