I don't really understand how the broken arm on a FAKA trebuchet works. Is it just an axle going through two pieces of wood and letting it drop until friction catches the loose arm or is there some type of mechanism that makes the loose arm move after the fixed arm hits a certain angle? If someone could help me I would appreciate it.
The Secondary Trigger. See the FAKA Page of information. In general, it is not based on friction. Even without a secondary trigger (which is sometimes done, though I think its a poor choice), the arm torque on the arm will naturally switch directions during the throw starting it moving. Also, nothing about the arm is "Broken".