| 1939 LLOYD RITTENHOUSE Signal Device Patent |
| 1939 MARX LOUIS Siding Control Signal Toy Railroads |
| 1939 UNION SWITCH SIGNAL CO Train Control System |
| 1939 SPARKS WITHINGTON CO Warning Signal Patent |
| 1939 GUYMAN CLARENCE Trawling Signal Patent |
| 1939 NICHOLSON Line Release Clip Signal Patent 7012 |
| 1939 FIELD Light Signal For Railroads Patent |
| 1939 STEVENS Pneumatic Signal Device Patent |
| 1939 SCOFLELD THEODORE Warning Signal Patent |
| 1939 LUECK LAWRENCE Distress Signal Patent Print |
| 1939 NICHOLSON Line Release Clip And Signal |
| 1939 SEAMAN DELBERT Signal Switch Patent Print |
| 1939 EAVES Audible Railroad Signal Patent Print |
| 1939 CRITEHFIELD Sounding Signal Device Patent |
| 1939 MAUD COURY Antitheft Signal Device Patent |
| 1939 UNION SWITCH SIGNAL CO Recording Mechanism |
| 1939 UNION SWITCH SIGNAL CO Interlocking Control |
| 1939 UNION SWITCH SIGNAL CO Remote Control System |
| 1939 WILLIAM Automobile Direction Signal Switch |
| 1939 SUBMARINE SIGNAL CO Sound Transmitting Receiving |
| 1939 ATLANTIC COAST FISHERIES CO Trawling Signal |
| 1939 UNION SWITCH SIGNAL CO Railway Signaling |
| 1939 UNION SWITCH SIGNAL CO Railway Switch Operating |
| 1939 CARL H FOWLER Audible Railroad Signal Art |
| 1939 UNION SWITCH SIGNAL CO Electrical Relay Art |
| 1939 ZIEGLER Hot Box Detector Signal Appliance |
| 1939 EAGLE SIGNAL CORP Timing Switch Mechanism |
| 1939 WESTINGHOUSE AIR BRAKE CO Pneumatic Signal |
| 1939 A E RITTENHOUSE CO INC Signal Device Patent |
| 1939 LINDSEY Signal Device For Railroads Patent |
| 1939 WELD Warning Signal Mechanism Art Print |
| 1939 ANDERSON Railroad Grade Crossing Signal Art |
| 1939 WESTINGHOUSE BRAKE SIGNAL Automatic Slack Adjuster |
| 1939 HOWARD Vehicle Signal Switch Patent Print |
| 1939 UNION SWITCH SIGNAL CO Railway Signaling System |
| 1939 RITTENHOUSE Housing Signal Tool Patent 26159 |
| 1939 GEN MOTORS CORP Sounding Signal Art Print |
| 1939 SCHAFER Antitheft Signal Device Patent |
| 1939 GEARIN DEWEY Signal Guard Patent Print Art |
| 1939 GEN RAILWAY SIGNAL CO Light Signal Railroads |
| 1939 UNION SWITCH SIGNAL CO Switch Control System |
| 1939 GEN RAILWAY SIGNAL CO Control Switch Patent |
| 1939 GAMEWELL Warning Signal Mechanism Art |