What is this?

One of my historical society friends (I heard that! - yes, I do have more than one!) found the pictured object during excavation at the site of a railroad station that was built over a hundred years ago. It appears to be cast iron, about one foot long, with semi-circular mounting flanges at the midpoint, and, not visible in the photos, annular scratches on the inside that suggest it was used to clamp or retain a circular movable object, such as a metal rod. "B&M" and "4" are cast near one end, and "048" at the opposite end. I can't guess the function of the two projections on the side, but the observation that one of them is cracked probably explains why it was discarded.

http://photos.nerail.org/s/?p=218534" onclick="window.open(this.href);return false;

http://photos.nerail.org/s/?p=218533" onclick="window.open(this.href);return false;

PBM

Almost looks like a cast wheel bearing shim. That would be my guess

I would go with Mike on that one. I've seen a few of these myself. The outside is shaped to "nest" inside the journal box. The grooves on the inside are to allow oil to seep in to reach the bearing surface.

Thank you, gentlemen, I believe I've got it. I found this drawing of an arch bar truck that appears to clearly show the shim front and center, mounted in place.
http://photos.nerail.org/s/?p=218563" onclick="window.open(this.href);return false;
PBM

Good deal, man... and nice find on that drawing!

I'd be surprised to see cast iron used as a bearing material. I think this is a bearing 'shell'. I think they put this part into a larger mold which formed the cylindrical axle opening and poured molten Babbitt metal into the interior, where it was held in place by the grooves. When the iron cracked, they would have melted the Babbitt out of it but maybe not have hurried to scrap the shell if the price of cast iron was low.

jbvb,

I agree, cast iron would make a pretty poor bearing surface. There would have to be a liner or sleeve or something similar between the shim and the axle bearing, which is not depicted in the small-scale drawing or evident from the photos, but I believe we have identified the object.

PBM

This is not the bearing surface. It is a shim. Holds the bearing material in place. I found one recently that the bearing had failed and the axle wore a grove into the shim.