Analysis of information sources in references of the Wikipedia article "سير مسنن" in Arabic language version.
Sprockets on the cam and intermediate shaft are twice the diameter of the sprocket on the crank, so for every two turns of the crankshaft the cam and intermediate shaft is turned one time.
This should be checked at the midpoint between the cam sprocket and the crankshaft sprocket.
sprocket pitch circle
This should be checked at the midpoint between the cam sprocket and the crankshaft sprocket.
Sprockets on the cam and intermediate shaft are twice the diameter of the sprocket on the crank, so for every two turns of the crankshaft the cam and intermediate shaft is turned one time.
sprocket pitch circle