Help with Bausch Lomb old shutter

[lungovw]

I recently acquired an old Planar mounted in a Bausch Lomb shutter and I was not able to figure out how it works. I understood where and how speeds and apertures are set but not quite about how to fire it. I noticed that I have to turn lever A clock-wise (in attached picture) to arm it, and I can fire it by lifting arm B. But I believe there might be another proper way to fire it. Does anybody could indicate an online source or share any literature about this shutter, or at least tell me which model it is? I tried already a search but to no avail.

[Steven Tribe]

It looks like a lot of similar first generation shutters like the unicum. THere are some photos of the inside of the dial and the main spring here (Search for unicum!). Bilb air release is through the cylinder on the B side, whilst the other cylinder is a brake cylinder and there is no opening at the end. The piston must be free to move in the cylinder.