A HOT BOX.
When a box heats in the least degree, it is a sign that for lack of oil or for some other reason the metals are wearing together.
The first thing to do, of course, is to see that the box is supplied with plenty of good oil or grease.
If this does not cause the box to cool off, take it apart and clean it thoroughly. Then coat the journal with white lead mixed with good oil. Great care should be exercised to keep all dirt or grit out of your can of lead and away from the bearing.
Replace the oil or grease cup, and the box will soon cool down.