The B&O "President" Class Pacific locomotives had various driver configurations over their lifetimes, often taking on boxpok drivers for some or all positions - especially in the later incarnations. I know there are a few flavor of boxpok style drivers (General Steel Castings, Baldwin disc, Scullin, and Universal). Can anyone here shed some light on which variety were used on the P7's? If there is any difference between P7 instances, I'm particularly interested in the 5306 "President Van Buren".

There is only one 'Boxpok' (it was a copyrighted tradename). There are a couple of technical variants in the coring (for example, for different styles of counterweight provision, and a pocket for those roads that used cross-balance weighting at 90 degrees) but the general appearance of the drivers was common.

Some of the disc centers were not cast, but fabricated. The general subject is discussed in some respects in the relevant sections of contemporary Locomotive Cyclopedias. Here is an illustration in a recent thread on another forum that shows some differences:



To my knowledge all the B&O disk drivers applied to the P7s were GSC Boxpok - unlike the NYC switching between Boxpok, Scullin disc, and Web-Spoke cast centers in the latter years of the J3a Hudsons. I found it interesting that 5304 had a full set of Boxpoks during and after the Kuhler streamlining, but these were replaced with spoked drivers when the Olive Dennis Cincinnatian streamlining was installed...

I can't give a definitive answer, but photos appear to show GSC Boxpok or "standard" spoked drivers, often with both styles on the same loco. I've never seen Baldwin discs or Scullins on a B&O engine. The only P-7 survivor, number 5300, rests in the B&O Museum in Baltimore with Boxpok main drivers and the other driving wheels spoked. Maybe somebody can visit the B&O Museum for a firsthand look. Information may be cast into those Boxpok main drivers.

Tom

Thank you (belatedly) for your responses. Since posting my question, I have obtained some engineering drawings for the locomotive in question. These plus a few photos I came across show boxpok for the main driver positions, spoked for the others. I still couldn't say which style boxpok it is by name, but at least I know what they look like now. I am building a virtual B&O 5306 in the computer. I'll try to post some pics to show how it's turning out, and to get pointers from the experts about correct configuration.