armature problem

using the ipo thingy i need to get the green part to always connect with the blue piece.
on the right hand side is an orangish part that i need to move ONLY in the x direction, but i need the bottom piece to remain connected to the big pinkish piece.
does this all make sense?.
the bits that stick out the right side are pistons so they have to stay level.
if i rotate the green bit then the top one wont stay level.

PS see the arrow on the blend file? what is the item i have it pointing to?
thanks all

PPS i had to remove the other wheels to get the file below 1meg. has the new forum page increased that limit?


BBarmatureproblem.blend (914 KB)