If you want to see, you have to Look.
I agree...very nice combination of colors. I'm not 100% sure, but I believe the wheels are used when that section of the boom is lowered and extended for disassembly. It allows the end to roll along the ground until is is completely flat. Once it is flat it can be taken apart for transport.
This looks like a large Manitowoc construction crane that has the upper boom resting on the ground to remove tension from supporting cables. Tom may have the answer about the wheels. It does make a great composition with the contrasting blues and red.