How to animate mechanical parts

Hi, 

   I have 3 mechanical parts in AftereEffects A, B and C on different layers. There are 3 axis of rotation m, n and o. Green part is rigid (static). How to animate A around m in such a way that B should move respectively (B is attached to axis n) but other end of B is also attached to C on axis o. B should push the C in a linear direction along with Brown part.