Concerning the lateral motion devices: You can see in the photo from the front end, the two red springs mounted on the bearing boxes. These two spring units extend into the oversized pedestal channels 5/8" and keep the bearing boxes centered on tangent track. When the lokey negotiates a tight right hand curve the first driver will shift to the right by 5/8", compressing the right red spring and the #2 and #3 will shift to the left, compressing the left spring. (The #4 driver has no lateral motion device.)as the curve straightens out, the compressed springs push the bearing boxes back in line.

Concerning the rods when the boxes are out of line: the drivers are 74" in diameter, and there are a few inches in between the driver sets, so the connecting rods are nearly 7' long center to center on the pins. Now if you take a 7' rod and move one end over 5/8", the change of the angle on the other end is nearly imperceptible. What little change there is is taken care of by the slop in the bearing which allows the grease to flow between the bearing and the rod and the crankpins. Any grease displaced by this change of angle will be redistributed when the engine in once again on tangent track.
Concerning the difference in weight distribution front and back:
Remember that the air pumps have been removed from the pilot deck which would add about 4000 pounds to the front end. The superheater units and all the tubes and flues are also out of the engine. In their installed position they sit closer to the front than to the back, and therefore would add more weight to the front end.
I suspect that with all that back on, the weight distribution would be nearly equal (that is until the crew climbs on board!)
Concerning the weight on the four axels instead of eight: The springs on the lead truck and trailing truck were blocked so that essentially we had two unsprung shop trucks which easily handles the much lightened load.

Thank you; that was very enlightening.

Steve

[quote="filmteknik"] If the pin, after emerging from the press-fit into the wheel, took on a slightly spherical shape, with rod bearings to match, that would solve the issue nicely. But of course they do not.

Steve[/quote]


Baldwin'Santa Fe used spherical bearings with their lateral motion setup.

Hello,

With an 84" pin center, a 5/8" lateral shift only reduces the effective rod pin centers 0.0024" over the axis parallel with the frame, basically within the running tolerance of the bearings and inperceptible. Obviously the frame pedestal openings are fixed so the axles move together that slight amount.

Perhaps comment could be made on how much clearance is given to plain rod bearings versus the pin? Too much would increase rod hammer?

You would think on roller bearing side rods, those external clearances could be tightened since the rod end bore is supporting the outer race of the roller bearing and does not need "running" clearance.

Regards,

Randy