(LFT series)
Development of Low Friction Torque/High Wear-Resistant Tapered Roller HUB unit

JTEKT Corporation (hereinafter JTEKT) has developed a tapered roller HUB unit for wheels (hereinafter T-HUB), by adopting the technology of torque reduction and wear-resistance improvement developed for the ball HUB units (hereinafter B-HUB).
The T-HUB is a HUB unit used for relatively large size vehicles, such as pickup trucks and full-size SUVs. The newly developed product contributes to the improvement of fuel efficiency by significantly reducing torque compared with the conventional HUB, while improving the wear-resistant performance during vehicle transportation through cold regions.
(Ref.: News Release on B-HUB development, http://www.jtekt.co.jp/e/news/160524.html)
JTEKT group adds this T-HUB to the line-up of LFT series and aims to expand the sales of T-HUB to various companies all around the world, especially Japanese, European and US automotive manufacturers.

JTEKT Corporation has newly created a tagline “Key of your operation Koyo” for the bearing brand “Koyo”. JTEKT will continue contributing to every industry including automotive manufacturers as an indispensable partner to solve customers' problems through working with customers and to provide benefits.

* LFT is an abbreviation for Low Friction Torque, and is a registered trademark of JTEKT Corporation.

Features

(1) Achieved pre-eminent torque reduction

[Point of development]

[Results]
Achieved 40% torque reduction compared with the conventional standard low torque T-HUB
Contributed to 0.5% improvement in vehicle fuel efficiency by using this T-HUB units on all four wheels

(2) Improvement in wear-resistance during vehicle transportation through cold regions

[Point of development]
Used additives suited to a low temperature environment, and improved the low temperature performance of base oil

[Result]
Reduced HUB raceway surface wear caused by vibration during train transportation of newly manufactured vehicles by 40% compared with the conventional HUB
(Especially, in extremely cold regions such as Russia and North Europe)

1.Detailed description

A HUB unit (hereinafter HUB) is used as a bearing which supports the wheels of automobiles. As the global regulations regarding fuel consumption and CO2 emission are gradually tightened, each automotive manufacturer continually sets higher goals concerning fuel consumption. Although fuel consumption regulations have mainly targeted passenger vehicles so far, recently the scope of regulation has widened to include large vehicles, such as pickup trucks and full size SUVs.
HUBs of large size vehicles use tapered rollers as rolling elements instead of balls so that they can withstand larger loads. Focusing on this point, JTEKT aimed to contribute to the improvement of fuel efficiency by reducing the torque of tapered HUBs (T-HUBs).

(Torque reduction)
A HUB, which consists of the “bearing that facilitates smooth tire rotation” and the “seal which prevents muddy water splashed by tires from entering the inside of the bearing”, loses torque due to “(1) bearing rolling resistance” and “(2) seal sliding resistance”.
For T-HUBs, we proceeded with the reduction of bearing rolling resistance using the conventional torque reduction techniques including optimization of shape and roughness of the inner ring rib/roller contact area and a special design for the crowning in the inner/outer ring raceways.
In order to further reduce these resistances, we applied the low viscosity grease developed for B-HUB, and refined the development of the grease by optimizing the base oil, thickener and additives for the T-HUB environment.
For the seal part, in addition to switching to a low torque type double axial lip seal, we employed a specific grease to be used only in the seal that utilizes an ultra-low viscosity base oil to achieve the best oil film characteristics that lead to the highest torque reduction around the seal lips.
As a result, the torque was reduced by 40% compared with the conventional low torque T-HUB.

(Wear-resistance)
When newly manufactured vehicles are transported by train in an extremely cold environment, such as Russia and Northern Europe, the raceway surface of HUB can be worn down due to the shaking at rail joints.
For this developed product, we added an additive suited to low temperature environments to the grease for the bearing part and improved the low temperature characteristics of the base oil to raise the wear-resistant performance of the grease, which reduced the bearing wear amount by 40% compared with the conventional HUB.

2.Sales plan

3.Manufacturing plan

Kagawa Plant
Koyo Bearing North America LLC (JTEKT group company)
JTEKT (THAILAND) CO., LTD. (JTEKT group compan)