Discussion relating to the PRR, up to 1968. Visit the PRR Technical & Historical Society for more information.
  by Allen Hazen
When did lateral motion devices on the driving axles of steam locomotives start to get used? "Blind" (flangeless) driving wheels on at least some axles seem to have been a common feature in early 20th C steam locomotive design (the Pennsylvania Railroad's I-1 Decapods famously had three axles with blind drivers when they were introduced, though later only the centre driving axle was so equipped), but some of their later steam designs with even longer "rigid" wheelbases had flanges on all drivers: I assume that lateral motion devices are what made the PRR's designers think this was reasonable. Followup with links to diagrams to follow up.

(Cross posted to Steam Locomotives forum.)
  by Allen Hazen
From a Web site devoted to the Altoona Works (past and present-- there are also drawings of the cabs used on current NS diesel rebuilds), here is the I1 as built: note the three blind driving axles:
http://www.altoonaworks.info/graphics/drawing_i1s.jpg" onclick="window.open(this.href);return false;
(From the format and, particularly, the style of the caption, I'm guessing that this drawing appeared in some edition of the "Locomotive Cyclopedia.")

The PRR's penchant for putting flangeless drivers on their locomotives wasn't limited to types with five driving axles-- here is the H6 Consolidation, with the second and third drivers blind:
http://www.altoonaworks.info/graphics/drawing_h6.jpg" onclick="window.open(this.href);return false;

Nor was the use of blind drivers on eight-coupled power limited to the very start of the 20th C-- here is the C1 switcher of 1925:
http://www.altoonaworks.info/graphics/drawing_c1.jpg" onclick="window.open(this.href);return false;
(Mind you, if Alvin Stauffer's "Pennsy Power" is to be trusted, the C1 wasn't one of the PRR's outstanding successes, being derailment prone…)

Indeed, sometimes the centre drivers of six-coupled locomotives were flangeless-- here is a well-known Pacific:
http://www.altoonaworks.info/graphics/drawing_k4.jpg" onclick="window.open(this.href);return false;
(Another drawing shows the experimental K5 Pacific of 1929… also with the centre driver blind.)

Indeed… Here is an 80-inch drivered Atlantic, apparently built for Atlantic City trains (where the Reading even used 4-2-2 power):
http://www.altoonaworks.info/graphics/drawing_e1.jpg" onclick="window.open(this.href);return false;
It LOOKS as if the first driver was blind-- can this really be so?

(Cross posted to Steam Locomotives forum.)
  by JimBoylan
According to a Railroad Magazine article about 1960, the Vandallia RR in Ill., a PRR predecessor enroute to St. Louis, had 4-4-0 American steam locos with the leading drivers blind until they derailed too many times. I'm not sure how much play was in the leading truck, the engine might have had an 8 wheel rigid wheelbase!
At Delair, N.J. on sharp curves, the PRR had blind driver rails on the insides of the running rials, to keep blind driving wheels from falling to the ties.
  by Allen Hazen
Jim Boylan--
Thanks! … The extra rails on curves sound like a sensible idea when you have a fair number of engines with blind drivers. My impression is that blind drivers often had slightly wider tires than flanged ones: one way to ensure that the blind driver doesn't fall to the cross-ties on a curve. The other way, of course, would be to widen the rail-head instead, which is essentially what the extra rails do!

(B.t.w. I posted my question to both the PRR nd the Steam Locomotives forums. I have now had informative comments on both, so anyone interested has two places to look!)