A question about bolster to bolster truck centers

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I have been measuring with my handy HO scale ruler and I need some info.

I checked on one site that offeres this info .

I build a GP-35 from a railpower products shell and all there was for a frame was a Athearn I modified to fit . The prototype is 34' yet the model is just shy of 32' and then what can't be right is the distance from the truck center to the back of the pilot and the site says 3' 10" yet just like the GP-30 the front truck is not as close to the front pilot and the rear is.

A SD40-2 is supposed to be 43' 6" yet the Athearn model is 41' 6" .

Then on the Railpower shells and frames I have a SD-40 and SD-45 and they use the same frame , on the model it's 38' on the prototype it's 40' SD-45 and 43' 6" SD-40 . Railpower lists the same frame for the SD40, SD38 and SD45.

The only one so far is the Athearn GP-38-2 and it is 34' and that is correct on the model.

I Know they model makers compromise . Not that it matters they look ok .

I made a GP-30 once using an older HO Lionel shell which was later used by either front range or someone then they added riviets to the roof and Bachman used the same shell with small details added and the fisrt time I got a proto GP-30 the first thing I noticed was the farther distance between the front truck and pilot and rear truck and pilot the front truck is further away from the pilot and the GP-35 should be.

Like I said nothing I can do about it it was like the old Atlas C424 and RS-11 . So I ask have I got the wrong prototype info , it's the only one I could find.


Milw Road in SW Wisconsin
Athearn Truck Spacing


Most models has a somewhat shorter wheelbase due to clearance issues - I suspect the trucks might have swing issues with the steps if they were perfect. As you noted, the prototype has 34' centers.


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