NTN Bearings Develops the Revolutionary SFJ, Shudderless Freering Tripod Joint

Constant velocity Joints (CVJ's) are used in a variety of applications including front-wheel-drive (FWD) and four-wheel-drive (4WD) vehicles. Because they efficiently deliver torque to the wheels, providing turning flexibility, they are indispensable for stable and smooth driving. Here we introduce the new SFJ (Shudderless Freering Tripod Joint) which has even better performance than other CVJ's.

SFJ (Shudderless Freering Tripod Joint)

What is the SFJ?
A drive shaft is comprised of a shaft flanked by two CVJs, generally of different types. Usually a fixed joint CVJ, for example a ball fixed joint (BJ) or undercut free joint (UJ) is installed on the wheel side, while a sliding CVJ called a plunging joint, such as a double offset joint (DOJ), a tripod joint (TJ), a freering tripod joint (FTJ) or a cross groove joint (LJ) is used on the engine side. The SFJ introduced here is an improved FTJ and it ensures a smoother, more comfortable ride.

The SFJ Mechanism and Future Potential
TJ type CVJ's have low slide resistance and are highly effective in eliminating vibration during idling for A/T vehicles. However, resonance between the engine mount and the CVJ's induced cyclical axial load sometimes causes shudder when the vehicle starts to move. Consequently, there was a strong demand from automobile manufacturers for a CVJ with less induced cyclic axial load.

We began with a standard TJ, developing and mass producing low vibration joints known as the AC-TJ and the FTJ. Subsequently, in response to requests from automobile manufacturers for even lower vibration, we developed the SFJ. Because we were able to keep costs lower than those for the FTJ, we have received many inquiries, not only from Japan but also from automobile manufacturers in North America, Europe and Korea. Since March 1997, the SFJ has been used in Fuji Heavy Industry's FWD and 4WD Legacy and in the 4WD Impreza and Forester. Some of the above, we have been told, were only made possible by the new SFJ. A dramatic new development, the SFJ is an outstanding CVJ. (Y. Tanigaki, NTN Corp. Osaka, Japan).