Question of MTH Premier Scale Wheels vs High rail wheels on 3R Scale?

Lee

Since you mention fixed pilots I assume you are interested in diesels.  If you run a 2 rail version of an MTH diesel (indicated by the -2 on the end of the item number) you will have two disadvantages over the standard 3 rail (-1) version.

First, you will have wheels with the RP-25 contour.  These look nice but are not designed to run on three wail switches.  Diesels with 3 axle trucks may ride through switches without too much trouble but 2 axle trucks will bounce as the unsupported wheels dip through the switch frogs.

Second, you will give up a lot of tractive effort since the 2 rail wheels do not have traction tires.

Both problems can be addressed by replacing the 2 rail wheel sets with three rail wheel sets.  MTH sells 3 rail diesel wheel sets separately for those wanting to convert their diesels for 3 rail scale operation.

Steam locomotives have other issues.  The 3 rail versions have blind flanges on the center axles and the 2 rail versions have all axles flanged.  That usually requires about double the radius of the 3 rail version.

Lee:

I am not an O Gauger, but model in S.  I have had no problems running hirail wheelsets with scale locomotives.  After purchasing my 1st Lionel locomotive, the U33C, I realize that if I attach the pilot, I will need a much larger radius curve.  This radius would be determined by the length of the locomotive and the number of drivers if you are talking about a steam locomotive.  I could never be able to run the U boat on regular AF curves (20" radius) and expect it not to derail the attached cars.  It will be fine with my minimum scale radius (36"). 

Biggest advantage of the larger radius curves is the visual aspect.  Your locomotives and cars will look much more realistic.  Bottom line is the amount of work needed to attach the pilot (there is a thread on the O 2 Rail forum you might want to take a look at) and the room needed to lay the larger radius curves.

Thank you for your replies, I do keep a little two rail O so... it's ok.

As far as my thinking is leaning to 0-74 curves and compromise by getting diesels that have the non fixed pilots.

My journey into O has been a interesting one this year with a developing of a possible train room and eventual planning.

I run fixed pilots with hi rail wheels it works great and looks so much better then the odd swinging pilot.  3RS is essentially 3 rail scale trains with fixed pilots