The Cyclelock was available in 1941
http://www.trfindley.com/flschwinn_1941_1950/1941_cc_010_011.html
D97XE-1 Special for reference
http://www.trfindley.com/flschwinn_1941_1950/1941_cc_004.html
http://www.trfindley.com/flschwinn_1941_1950/1941_cc_010_011.html
D97XE-1 Special for reference
http://www.trfindley.com/flschwinn_1941_1950/1941_cc_004.html