@SantaFe158 posted:One thing to note, many mid-1800s 4-4-0s (and some other types of that era) did have blind drivers on the first axle. The B&O #25 "William Mason" is one such example. The lead truck simply pivoted as any other truck would about one axis and wouldn't have had the lateral motion swing links that later locomotives acquired as technology progressed, therefore it kept the front end of the locomotive on the rails. The blind drivers were typically wider than a flanged driver as well to prevent issues such as what the models described above are experiencing.
It appears that the replica 119 and Jupiter locomotives have flanged drivers on both axles, but perhaps some reference was found to say the original prototypes did not?
The Wm Mason was built in 1856 by Mason Machine Works. The UP 119 was built 12 years later, in 1868 by Rodgers Locomotive and Machine Works. That's enough time for the suspension technology to improve, along with perhaps two different engineering philosophies.
Rusty
