the "Truck" isn't a truck.
Trucks in front and back are extra Tow power for self-propelled sections. The "Box" on back of them is dead weight to get more traction for them. You can add more trucks, remove them like shown, or change tow truck types as needed.
Cab(s) are put in the self-propelled load carrier/"frame" just so driver(s) can sit in AC space for hours to days.
Diesel Motor drives a Hydro pump and each dual set has a Hydro-engine in them.
Most can be recofig to have more or less "axles" to handle a given load as above or in 1 piece w/o anything bridging in middle.
for that each half is config w/ 8 "axles" w/ 4 sets of duels = 64 tires. 120 tires total the add float tires for Tow trucks.
Is hard to see but each wheel set has a ram to adjust suspension for each set as road changes. Also means Changing tire(s) is "easy" because can self jack a set of wheels to change/fix a flat tire. To get at inside dual like just jack and rotate to move inside to outside w/ Hyrdo pivoting at top of them.
If you watch carefully when turning... each axles, likely even each set on an axle, gets different turning radius. This is controlled by hydro-pivots for each set and likely a computer.
I've seen bigger "rigs."
Forgot what county but had bigger version of above, times 2, then a third bridge carrying the actual "part."
------------------Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)The Ogre's Fiero Cave
[This message has been edited by theogre (edited 12-01-2019).]