The main sizes of the tapered roller bearings conform to DIN ISO 355 and DIN 720. Dimensional and running tolerances correspond to tolerance class PN acc. to 
DIN 620. These tolerance classes are standard and are perfect for most applications.
The bearings are separable. This implies the bearing parts could be fitted independently of each different. The bearings are provided without seals. They might be lubricated with grease or essential oil from the side.
The rollers are processed to create pore-like micro indents in the surface of the steel (rolling contact area and roller head). This microstructure helps maintain an oil film that’s perfect for tapered roller bearing applications. Improved essential oil film retention substantially inhibits surface damage, obtaining more than eight moments higher durability and equal or increased seizure resistance in comparison to conventional products.
Improved lubricant oil accumulation and retention (simpler to form oil film) in the roller surface contributes to 10% lower friction for low speeds in comparison to conventional products.
Tapered roller bearings may accept high radial and axial loads. Axial loads are absorbed in mere one way. For axial counter support a second bearing mounted inverse is required. Ideal for medium speeds.
Bigger efficiency transmission systems have emerged as key to increasing fuel economy, so NSK set out to develop a substantial reliability bearing capable of overcoming these hurdles.
To improve fuel economy, there’s been a shift to using less lubricant and/or cheaper viscosity lubricant in tranny systems. Consequently, tapered roller bearings in transmissions are being subject to increasingly severe lubrication conditions, increasing the risk of lubrication oil film depletion (lean lubrication circumstances), surface damage, and bearing seizure.