Like yann said there are many ways to rig this type of mechanical structure.
I used a Track To Bone constraint on the support bone that goes between the top and the road.
The rig set up is rather simple. The road bone (the bone selected in the gif) has a Limit Rotation constraint on it, that is the bone I rotate.
The top bone is simply copying the rotation of the road bone, via a Copy Rotation constraint.
Now the support bone is parented to the road bone, thus the location of the head stays correct. Now in a perfect setup all you would need to do is uncheck Inherit Rotation for that bone, and you'd be done. However it is probably better to use a Track To constraint to make sure the tail of the support bone stays exactly at the top where you want it. I have the Track To to the tail of my top bone.
The blend because I know in rigging it helps to see what is going on.