From time to time we’ve discussed flooring next to vault doors that can be lowered to allow the door to swing. This allows the opening to be more use-friendly. In an earlier thread (http://www.antique-locks.com/showthread.php/2315-York-Round-Door) Doug MacQueen discussed his experience with a large York door and its movable floor segments.
I ran across some US patents related to such flooring –
1,180,106 Depressible Flooring, Thomas M. Brintnall, 1916
1,369,960 Bank Vault Flooring, Thomas M. Brintnall, 1921
1,547,556 Automatic Floor Structure, Thomas M. Brintnall, 1921
1,578,004 Counter Weighted Lowering Floor, Thomas M. Brintnall, 1926
These were found because in another thread discussing the National Bank of Arizona in Phoenix, Brintnall is given credit as the vault designer so I went looking for his patents on http://www.freepatentsonline.com.
