I am wondering about the advantage of dozer push beams in side or outside of the track. Can I get the pros to school me on this?
well, usually if the arms are on the inside, you are looking at an angle blade. that is unless you are looking at a d8-9-10 pushcat. arms on the inside give the blade room to angle, but, i feel you lose some strength. outside arms are the norm on bigger dozers and usually don't allow for angle. usually. some outside armed dozers angle, most notably would be pipleline re-spread dozers. see, dozers are pretty simple, huh?
The arms are inside on a C-blade because the blade is narrower so the push-cat can follow the scraper thru the cut. C-blades are sweet to push with. You don't have to worry about catching a scraper tire or pushing a rock into a scraper tire. Clear as mud right?
SU and U blades have the arms on the outside, give a lot more of the strength to to the corners of the blade, this comes in real handy when prying out boulders or pushing a big load. And as said VPAT blades are on the inside to make better room for the blade to angle, or for the pushblades which are narrow because, well they just need to be as wide as the scaper they are pushing. Course you have variations throughout all the blades.
The A blade seems to be more popular up here (Canada) than the U.S. It has an outside push frame and angles manually either way. I think outside frames are slightly better as they push from a slightly lower position on the track frame rather than on the tractor body. By that I think it is better as to strength and ease of maintaining grade.