This one is from before 1927, when an "improvement" to it was patented.
It is a rotating type, and had a pin set up externally to trip the head by pushing in the lever. I have never seen the pin setup, and can't find a patent for the head prior to the 1927 improvement.
The improvement was to add a "tripping shell" with a sloping groove, that was held back by a fork setup, to trip the lever when the lever was pushed in by the sloping internal groove in the shell as the head advanced.
This unit never had a shell, it is prior to that.
It is a rotating type, and had a pin set up externally to trip the head by pushing in the lever. I have never seen the pin setup, and can't find a patent for the head prior to the 1927 improvement.
The improvement was to add a "tripping shell" with a sloping groove, that was held back by a fork setup, to trip the lever when the lever was pushed in by the sloping internal groove in the shell as the head advanced.
This unit never had a shell, it is prior to that.