A Pantographic Knife is a folding knife whose blade is opened by a unique scissors method. The manner is similar to a balisong knife (also called a butterfly knife in western countries) - with which it is often confused. But, unlike the balisong knife handles that swing freely and independently, the pantographic knife uses a pantograph linkage to keep the handles aligned during opening and closing.
The pantographic knife is very strong when compared to most other folding knife designs, being joined at several points and along several planes - this increases the force required to break the blade away from the handle. By enclosing the blade on both sides, double edged blades can be used. The Pantographic Knife looks similar to an OTF gravity knife used by German paratroopers.... hence it is sometimes called a "Paratroopers knife."
Wikipedia states some of these with brass handles with text in English language are post war (1948).
This is NOT an automatic, or spring assisted knife, or an OTF knife, there are no springs or assisted mechanisms, and takes two hands to open...
In the illustration:
- Figure A shows the closed knife, with blade retracted.
- Figure B shows the pantographic legs opening. The collar is shown sliding down the blade.
- Figure C shows the blade almost extended.
- And finally, Figure D shows the pantographic legs folded together, making a handle that is half as long as when the knife was closed.
Pantographic knife information & illustration courtesy of Wikipedia®