Tie Plate Hole Dimensions

Model Railroader Prototype information for the modeler
1

Hey, somebody had to ask, right?

I’ve been looking more carefully at original drawings–not a real tie plates. I notice that in both 3-hole flanged and unflanged, and in the more modern 4-hole double-flanged tie plates, all of the holes are not the same size.

For example, the punching for PRR 3-hole plates shows one 7/8" sq hole on the field side, and on the track side it has one 7/8" and one 1" sq hole. This is the layout for the 100 lbs plate. Now get this…

For the 85 lbs plate–same drawing–it has the same two 7/8" sq holes, one on each side of the rail, but now the 3rd hole is spec’d to be punch as 15/16".

Likewise on even newer 4-hole tie plates, regardless of rail weight, I see at least one hole punch larger. What’s up?

2

Bongo,

I took your hint, and looked at this question. I’ll check the drawings when I get a chance, but the thought that comes to mind is that the larger hole allows a spike to be driven right onto the rail to provide a bit more resistance to rail rollover in curves. But that’s just a guess.

Peter