Tractor carries more than his own weight on its trolley. The linkage between the tractor and the trolley is far away from the tractor. So, the whole weight of the trolley is on the back of the tractor. But why does not a tractor do wheelie with more weight on his behind?
To make it understandable, here are some photos I designed:
Tractor with empty trolley:
What is the reason for that?