| 1931 FREDERICK Ratchet Mechanism Timepieces Art |
| 1931 MAGEE Mechanism Attaching Fringe To Edges Carpet |
| 1931 GEORGE Valve Operating Mechanism Tanks Art |
| 1931 MCGLONE Retarding Mechanism Railway Rolling Stock |
| 1931 KNEELAND Charging Mechanism Blasting Cartridges |
| 1931 COLT S CO Reversible Feed Mechanism Machine Guns |
| 1931 ALBERT Impulse Mechanism Pendulums Clockworks |
| 1931 ANDREW A KRAMER Valve Operating Mechanism Tanks |
| 1931 WATERBURY CLOCK CO Ratchet Mechanism Timepieces |
| 1931 J E BROWNING Breech Mechanism Firearms Art |
| 1931 FAHRNEY Propelling Mechanism Boats Art |
| 1931 EDUARD Pointing Mechanism For Guns Patent |
| 1931 PEDERSEN Rear Sight Mechanism Small Arms |
| 1931 CLAUDE Starter Mechanism Lock Patent Print |
| 1931 COLT S CO Firing Mechanism Automatic Firearms |
| 1931 UNION Feeding Mechanism Top Rock Shaft Machines |
| 1931 HATCHER Belt Feed Mechanism Machine Guns |
| 1931 CRAIG Mechanism Lock For Motor Cars Patent |
| 1931 KIENZLE Electrical Striking Mechanism Clocks |
| 1931 ARTHUR Mechanism Use In Musical Instruction |