This was a switch lock on the famed Pennsylvania railroad.
The padlock is made of steel. On the front side, the swinging latch that covers the key hole has large embossed letters "P R R", and underneath that in smaller blobby letters "Slaymaker" (the manufacturer of the lock). There are a few other even smaller letters that are too blobby and small, hard to read. The letters, and therefore the latch cover, appear to have been cast, not stamped. There are no other marking on the lock, front or back.. This appears to be an older lock. The original chain is gone and there is no key.
The condition is very good.. The padlock body and shackle are still rust free. The surface texture of the lock is a bit odd, appearing sort of wrinkled and leathery in spots. Under magnification you can see it is just the original cast surface which was left as is, not ground down or polished. This is a nice display piece; a variation on the more commonly seen PRR switch locks.
This lock came from the Indiana estate of a long-time railroad employee.