The truck for the 2 axle locos was pretty uneventful. It was nice to go to ball bearings as it evolved, but still embedding wires in the block that pressed against the outer race of the ball bearing was not a good idea, shorting the block on a switch melted these wires into the case.
But the “prime mover” modular gearbox is a very clever design. It has it’s pro’s and con’s, but clever. Unfortunately sloppy assembly techniques caused it to have more problems than it should have, but consider that each gearbox had 4 ball bearings, and the axle ones had ceramic bearings, it was pretty cool.
There are other design flaws in the gearbox, but some very imaginative design there. At the very “end” of Aristo, they actually made axles and wheels that could not slip and you could adjust gauge. That part was something needed for 10 years, it’s too bad they figured it out and acknowledged the problem as they were sinking.
Greg