Yale & Towne Cast Bronze Pin-tumbler Padlocks - 800 Series Models - Manufacture Date?

[Iowa Tom L]

See image here from Supplee Hardware Co. catalog ca. 1902 which illustrates some paracentric Yale key blanks from the era:
http://www.antique-locks.com/attachm...chmentid=12252

Pete Schifferli

Thank you Pete, I appreciate the ad image. In my investigations on this site and others, along with searching out Yale ads; here is what I have been able to assemble on Yale keys for the 800 series.

The Yale Paracentric style key was patented on December 13, 1898 (US29786), I do not know when it went into production. Obviously, at least by 1902 as the image you posted indicates. Initially, the blade of the key contained patent dates and, on the reverse side of the bow, it had "Y & T Trade Mark" inside a trefoil outline.

By 1908 at least, the key bow maintained the same design but now "Security" was stamped on the blade (see attached images, key on the right).

The "Y&T" ceased to be the Yale trademark in 1909 and was gradually phased out; the 800 series padlock itself, retained it until about 1925. However, by 1915, the "Y&T" trefoil and "Yale Paracentric" had been phased out from the key bow (maybe someone can nail this date down better than me?). It was replaced by "YALE" with a plaque outline (see the attached images, key on the left) with "Security" stamped on the blade. This key design was in use from approximately 1915 – 1926 (again, maybe someone here might be able to provide more definitive dates?).

Around 1927, plaque outline was dropped and the Yale key design displayed “YALE” in uppercase, block letters without any outline. This key design was maintained through approximately 1971, after which “Yale” was displayed in uppercase and lowercase letters without a border.

So a Yale 800 Series lock with an original key would help establish the build date and it may even be associated with two original key designs. Did the Yale locks in this series start production with the "Patented..." stamp, or was it added later for a period of time? I know that Yale was producing this series with the "Patented..." stamp sometime after 1905; but did they begin production with the stamp?

Thanks to all of you for sharing your knowledge with me.

Tom