four-point contact bearing race profiles

[johnyeye]

Hi,

I am looking for the race profile/contour for four-point contact bearings. From reading through other threads I am aware that most use a Gothic arch design for the race, but I am looking for what the radius of one side of the arch would be relative to the ball diameter. I have the axial internal clearance specifications for four-point bearings and I need to design around 45 degree contact angles, a 15/32" ball diameter and there is not a cage for the balls.

For some background on this project, I am working on a 1903 White Steam Engine that has a crankshaft that spins on ball bearings, three radial and one four-point thrust. In addition, the two connecting rods and the Stevenson links also operate with ball bearings. The challenge with the job is that all of the bearing races are integral to the components in one way or another, substituting new complete bearings is out of the question, our only option is to grind the races for larger ball sizes. I have designed all of the radial ball bearings using race profiles of 53% ball diam for the outer, 52% for the inner, and C3 radial internal clearance, these bearings also have no cages and the outer races are split and bolted. Back to the four-point contact bearing, does each side of the Gothic arch follow the same principle as the radial, 53% and 52% of the ball diameter profiles?

Any advice and help would be appreciated.

 

[dinjin]

Usally they are the same for both sides.

 

[johnyeye]

Thanks for the information, I will adjust my design using the same radius for the inner and outer raceway Gothic arch profiles. I was planning on designing the axial clearance into the inner race by adjusting the distance between the two sides of the arch at their tangent point of contact with the ball, does this sound correct?

 

[dinjin]

I see no problem of making the inner be a closer conformance.
It probably would give you better life. When we make 4 point
contact bearings, ours are much larger and we grind both outer and inner to the same conformity. We are talking about much larger ball diameters ie 1.00 to 3.00 inch balls. I assume you are seeing greater wear on the inner races. How did you select the new ball size?

 

[johnyeye]

The ball size was selected from common nominal dimensioned balls, knowing that we would need to at least remove a minimum amount of material to clean up the worn races, instead of choosing a random number, we went for nice fractional size as a starting point. At the moment, we are having difficulty finding someone to jig grind the races since the first two shops turned down the job.