This is my largest Lego creation to not have any working electronics in it - its PFless. It was built for the August 2010 Technic Challenge
Besides having a fully-functioning crane arm (rotating base, lift via linear actuator, extending boom, adjustable counter-weight, and winch), the entire truck can be lifted off the ground by outriggers!! This is done by pumping the four pneumatic pistons located in between the middle two axles and behind the rear axle. The front two axles have stepped-steering -meaning that the front axle steers more than the second axle behind it. The V10 engine under the cabin is driven by the rear axles. The cabin itself, however, has its own function -the top half can be moved forward by rotating a gear on its side. As pictured below, this movement lifts a stand from above the engine -this serves as a place for the crane arm to sit on when it is lowered.