I am wondering if anyone knows when Yale started producing their cast bronze, pin-tumbler padlocks of the 800 Series (such as the 830, 840, 850, etc. models)?

I can find them in the 1908 Yale catalog but not in the 1893 catalog (I do not have any catalogs for years in between these). I have looked for patents and searched this forum unsuccessfully for an answer.

Based on their build characteristics, I am guessing that they started being manufactured sometime after January 1901 when the patent application for the locking of the heel and toe of the shackle was filed (Patent #US685289) and before the spring of 1908 when the catalog was published. The Yale Paracentric key with the round bow and Y&T trefoil design (Patent #USD29786) seems to be the earliest key design associated with this series of padlocks.

If someone on this forum could help me find the answer to this question I would appreciate it.

Thank You,

Tom