A shot these good questions

William,
Some good (and tough) questions. I think 497's poor tracking problems had several sources. They were ...1. The crude centering device on the number one driver did not work right for the reasons John Bush recounted above. 2. The engine had spring problems, and this may have affected its ability to negotiate curves. The engine's big problem was a lot of boiler on a K-36 frame. 3.Like the K-36s the K-37s had a lot of overhang in the back of the engine. This certainly may have been another factor in these big engines' tracking, as the tender and the drawbar stiffened the tracking somwhat. 4. At some point the D&RGW took the elevation out of many of the curves. Elevation works better at high speeds. At lower speeds there is accelerated rail wear. Apparently the K-37s liked the elevation, which actually lessens radius. K-37s did break more rail than other engines, simply because of its high axle loadings. If it wasn't at least 70 lb rail, it would break it, even in straight track. Like I said above, some engines in the K-37 class seemed to do just fine and were well-liked engines by crews. An interesting note- the best K-37 was kept in Alamosa (499). The worst K-37 (490) pensioned off on the Farmington branch, the last hurrah for any engine going to the dead-line.