branching out...

Atlas trucks have a truss bar across the top to support the hi-rail coupler. The trucks do move, but they're stiff. Operationally, it's not going to make a difference as Atlas cars track very well in a train.

but springs are just for looks on Atlas..

Springs are also just for looks on other brands too.  Aside from whatever visual satisfaction is gained by seeing the springs compress when you press down on them, there's no significant operational advantage one way or the other.

It's certainly that way on reefers _ I mix Atlas, MTH and Lionel and really, I can't see enough different to matter..  All of them roll basically unsupported by springs.  

Springs are pretty to look at.....the force needed to make them 'work' never happens as they run around the layout. Scale O3r trucks that are equalized via truck sideframes pivoting work as well or better.....IMHO

 

Very true, the only "force" that would be apparent is if a load is put in the car that's heavy enough to compress the springs, and that would result in a terribly heavy car or cars for the train to pull.  Again, there's no net benefit aside from the visual appeal of springs as a separately applied detail, in which calling Atlas O's trucks "sprung" is not misleading.

I beg to differ...
On an O scale train, pulling 35 rolling stock up a 4% grade, around a 40+" radius..on Gargraves track..those little springs compress and keep the train from derailing..and keep the outer wheels in contact with the rail...
And in my semi protypical universe I want springs that compress when I push down in the car..like my MTH and 1 Lionel rolling stock do...

I expected more from Atlas..they make nice HO turn outs..But I guess rolling stock is too difficult.....

 

I suspect you're more likely experiencing a placebo effect much more so than than any actual practical functionality the springs may provide.