Development of Low Friction Torque/High Wear-resistant Ball HUB units

JTEKT Corporation (hereinafter called “JTEKT”) has newly created a tagline “Key of your operation Koyo” for the bearing brand “Koyo”. JTEKT contributes to every industry as an indispensable partner to solve customers' problems through working with customers and to provide benefits.
We developed a ball hub unit for wheels (hereinafter HUB) for various types of vehicles from compact vehicles to SUVs by greatly improving the wear resistance during vehicle transportation in cold regions and significantly reducing the torque during regular use compared with conventional products in order to improve fuel efficiency.
JTEKT group will expand the sales of this product to various companies all around the world, especially Japan-affiliated automotive manufacturers.

1.Features

(1) Achieved pre-eminent torque reduction

[Point of development]

[Results]
Achieved 50% torque reduction compared with conventional products
Contributed to 0.5% improvement in vehicle fuel consumption by using this ball hub unit on all four wheels

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

[Point of development]
Combined additives suited to low temperature environments with the grease for the bearing part

[Result]
Reduced HUB raceway surface wear caused by vibration during train transportation of newly manufactured vehicles by 70% compared with the conventional HUB
(Especially, in extremely cold regions such as Russia and North Europe)

2.Detailed description

A HUB is used as a bearing which supports the wheels of automobiles.
Global regulations regarding fuel consumption and CO2 emission are gradually tightened. Therefore, JTEKT aims at contributing to the improvement of fuel efficiency by reducing the torque of HUB.

(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”.
This product was developed by especially focusing on the grease and seal shape in order to reduce the abovementioned resistances.
With regard to grease for the bearing part, we changed from the conventionally used mineral oil to a low-viscosity synthetic oil to optimize the grease composition according to the environments where HUBs are used, thus solving the trade-off relationship between long bearing life and low torque and achieving both of them at the same time.
Moreover, as for the grease for the seal part, we employed an ultra-low viscosity base oil to reduce torque while keeping the necessary oil film characteristics required for the seal lip.
For the seal shape, we employed the double axial seal which enabled torque reduction without a reduction in the sealing ability.
As a result, we have completed the development of the HUB unit which reduces torque by 50% compared with the conventional HUB.

(Wear-resistance)
When newly manufactured vehicles are transported by train in an extremely cold environment, such as Russia or Northern Europe, the raceway surface of HUB can be worn down due to the shaking at rail joints.
For this developed product, an additive suited to low temperature environments was added in order to increase the wear resistance of HUBs. Owing to this, the wear amount was reduced by 70% compared with the conventional HUB.

3.Sales plan

4.Production plant

HUB unit production plants in Japan and overseas