Ntn Corporation

Kouji Kametaka

Hisashi Ohtsuki

Kazuo Komori

Hiroki Tsuchiyama

Tadatoshi Suzuki

A vehicle wheel bearing apparatus has an outer member formed, on its inner circumference, with double row outer raceway surfaces. An inner member includes a wheel hub integrally formed with a wheel mounting flange at its one end. The wheel hub outer circumference surface has double row inner raceway surfaces arranged opposite to the double row outer raceway surfaces. Double row balls are freely rollably contained between the outer raceway surfaces and inner raceway surfaces, respectively, of the outer member and the inner member. A pitch circle diameter of the double row ball group of the outer-side is larger than a pitch circle diameter of the double row ball group of the inner-side. At least the outer member and the wheel hub are formed of medium/high carbon steel including carbon of 0.40&#x2dc;0.80% by weight. The inner and outer raceway surfaces are formed, respectively, with predetermined hardened layers with a surface hardness of 58&#x2dc;64 HRC. The grain size number of austenite crystal grains of the metallographic structure in the hardened layers is selected larger than #7.

Wheel bearing apparatus for a vehicle

A vehicle wheel bearing apparatus has a double row angular ball bearing including double rows of ball groups. A pitch circle diameter of the double row ball group of the outer side is larger than a pitch circle diameter of the double row ball group of the inner side. The outer member is made of medium carbon steel including carbon of 0.40&#x2dc;0.80% by weight. It is hardened by high frequency induction quenching so that each of the outer raceway surfaces is formed with a hardened layer having a surface hardness of 58&#x2dc;64 HRC. The effective depth of hardened layer is set at at least 2 mm. The minimum wall thickness of the outer member at these outer raceway surfaces is set at at least 4 mm.

Wheel bearing apparatus

A cam follower with roller of the present invention includes a cam follower body having a roller supporting portion integrated therein, a roller supporting shaft having both ends fixed to the roller supporting portion and a roller rotatably supported on the roller supporting shaft with a plurality of needle rollers interposed. At least one of the supporting shaft and the needle roller has a nitride layer on the surface thereof, and has a surface hardness of at least HV 650 and an amount of retained austenite of at least 25% by volume and at most 50% by volume. Thus, a cam follower with roller having excellent durability and fatigue life can be obtained.

Growing community of inventors

Iwata, Japan

Kouji Kametaka