Bearing with low wear and low power loss characteristics

In a differential for a vehicle, with the differential including a housing, head and tail bearings in the housing where they define a bearing axis, a pinion shaft mounted in the bearings for rotation about the bearing axis, a pinion on the pinion shaft and within the housing, and a ring gear in the housing and meshing with the pinion, whereby rotation of the pinion shaft will rotate the ring gear, and wherein the head bearing comprises:

• a cone fitted to pinion shaft and having a tapered raceway that is presented away from the axis, and a thrust rib provided with a rib face located on the thrust rib at the large end of the raceway and oriented at a substantial angle with respect to the raceway;
• a cup having a tapered raceway that is presented inwardly toward the axis and the cone raceway at an angle of 20° to 30° with respect to the axis;
• and tapered rollers organized in a row between the cone and the cup and having tapered side faces along which the rollers contact the raceways and large end faces along which the rollers contact the rib face of the thrust rib;
• wherein the ratio between the roller length and the diameter of the roller at its large end does not exceed about 1.5;
• wherein the raceways and the side faces of the rollers are crowned to provide reliefs at both ends of the raceways, and the reliefs are between 700 μin. and 1500 μin per inch;
• the rib face lying within a conical envelope having its center at the axis;
• the side face of each roller lying in a conical envelope having its center along the axis;
• the large end face of each roller lying within a spherical envelope having its center along the axis of the roller and a radius greater than 90% of the distance between the apex for the envelope defined by the side face and the spherical envelope of the end face measured along the axis of the roller.

A tapered roller bearing in a differential for a vehicle, for accommodating rotation about a bearing axis, said bearing comprising:

• a cone having a tapered raceway that is presented outwardly from the axis and a thrust rib at the large end of the tapered raceway, the tapered raceway being crowned, yet generally lying in a conical envelope having its apex along the axis, the thrust rib having a rib face to which the tapered raceway leads, with the rib face being presented at a substantial angle with respect to the raceway;
• a cup surrounding the cone and having a tapered raceway that is presented inwardly toward the axis at an angle of 20° to 30° with respect to the axis, the cup raceway being crowned and generally lying in a conical envelope that has its apex along the axis at generally the same location as the apex for the envelope of the cone raceway;
• tapered rollers arranged in a circular row between the cone and cup with each having a roller axis and also tapered side face along which it contacts the raceways and a large end face along which it contacts the rib face, the side face being crowned and the large end face lying in a spherical envelope having its center along the roller axis, the crowning of the raceways and the side face of each roller being such that the centers of the regions of contact between the side face and the raceways are offset toward the rib face, wherein the sum of the misalignments between the side face of each roller and the cone raceway and the side face of that roller and the cup raceway is between about 0.0003 and 0.002 radians.