I was disassembling an old SAFE brand PTPK padlock the other day to clean it and make a key for it.
I was surprised to find ball bearings in the lock.
From further research I think that the lock was made for SAFE Padlock and Hardware by Corbin Cabinet Lock Co. See http://antique-padlocks.com/ptpk_l_p-s.htm
I am including photos.
Hope this is some interest to somebody as I have not seen mention of ball bearings in a PTPK padlock before.