What are these type of gearlevers ?

[Gravity Aided]

Those large stem shifters are proprietary to an old lower end Schwinn of 1970's vintage. I could look around...
I think I may have given my last set to another bicycle aficianado a few weeks ago, but you never know.

 

[tyred]

I had some on a Gitane, used catch the rear lever with my knee if in a low gear and getting out of the saddle, let you work out what happens when you drop from 2 to 5 in half a crank rotation.

This. I have been using my obscure German mixte as a utility bike and it is actually a damn fine bike to ride but I need to be careful if riding out if the saddle as the stem shifter comes worryingly close to my knee.