Achim/Dave,
Many thanks for posting the images. Certainly looks like a Birkigt trigger motor to me, that's quite a coup. There is one rigged slightly differently in Woodman's "Early Aircraft Armament" on p 198. These are the type we need to complete restoration on our "Spad" Colt Vickers so expect that we will grovel a bit
.
I've attached images of the type C CC gear trigger motor for your comparison and a Hazelton device, we are also looking for these in case someone finds one in a yard sale. As always we are quite happy to reverse engineer from originals and return them unaltered. Again, congrats on your find Dave and thanks for sharing it with us. Do you know any of its history/application?
Best,
William