Thanks for the replies folks...
Sternjaeger,
The chaika doesn't have such a cog-rack construction. I don't know how it works on the chaika but Kodoss's his suggestion makes sense and matches with the pictures I have of the gear. Anyway, good picture of a basically very simple solution to rotate the main strut on the P-40.
Here's another great picture (although it doesn't show the hinge (left) clearly):
and also a clear picture of the construction as used on the P-40:
