Baldwin 60,000

[IA and eastern]

If i took off the water tube boiler what would have replaced or fixed to make this locomotive better. I am a railfan and not an engineer i would like hear from the engineering on would you fix this locomotive. Gary    

[CSSHEGEWISCH]

Speaking of water-tube boilers, I have never seen a good diagram of the layout of a water-tube boiler on a locomotive.  Most diagrams that I've seen show a stationary boiler (such as a power plant) layout.

[Overmod]

CSSHEGEWISCH

Speaking of water-tube boilers, I have never seen a good diagram of the layout of a water-tube boiler on a locomotive.  Most diagrams that I've seen show a stationary boiler (such as a power plant) layout.

Most stationary boilers are some variant of 'once-through' boilers (see Benson boilers for an example) which have a history of being tried on locomotives, with fairly uniformly dismal results.  Among other issues, their construction does not permit the effective range of 'turndown' typically encountered in normal locomotive practice, with the result often being, somewhat counterintuitively, overheating failure of components in the gas path.

The 'traditional' great problem with watertubes in railroad service is that they are expensive to fabricate and maintain.  A considerable amount of interest in this, much of it now lost, involved the implementation of good turbining systems that could negotiate complex tube bends.  In the steam-automobile community there is a fair amount of claiming that tapered-monotube boilers could deal effectively with feedwater scaling -- but when you actually look for numbers on this, there appears to be less and less actual evidence to back that up for the mileages a railroad application might be expected to run, and the water quality cost-effectively provided for locomotive use.

As an interesting aside, "locomotive boilers" in oilfield service were quite often operated at pressures up to 500psi with staybolted boilers, without much surviving evidence of either frequent or catastrophic failure.  It is not difficult to figure out the differences between this service and typical locomotive practice that explain why even 300psi in large locomotive construction could be 'pushing it'.

I studied the boiler on Baldwin 60000 fairly closely in my early teens, as I had occasion to be in Philadelphia fairly frequently and had an interest in watertube fireboxes -- which is what this is.  Railroad practice generally had little issue with firetube construction in the convection section, in part when structural welding of one end of the tubes became common practice, and this is greatly enhanced when (as in the Stanley boiler to a much more significant degree) you can populate more of the convection 'shell' with tubes and flues that constitute effective longitudinal resistance, with decent control of internal circulation to keep differential expansion effects on the tubesheets minimized.  So, in North America, the real interest was in replacing the expensive and fragile staybolted firebox with something using watertube construction (early, and not incapable, examples including the Brotan and McMillen types).  As I recall (it has been quite some time), the construction on 60000 involves multiple rows of what are substantially 4" boiler flues, arranged in four roughly vertical rows at a pair of receiving drums, coming down to two rows at a modified mud ring (which has enhanced circulation to the convection section).  The outside of the resulting 'waterwall' is insulated with reverberatory material.  (The locomotive as it exists is IIRC somewhat different from the pictures in the test documentation.)

This construction was intended to be somewhat less prone to differential-expansion issues than many of the more complex watertube-firebox or waterwall arrangements; it does not appear from the surviving test results (some of which involved oil firing) that there were tremendous incidences of common-mode failure attributed to this construction -- when it was new.  

It was surprising to me, though, that this would be used over a simple two-axle trailing truck, and perhaps that Baldwin did not repeat this on production locomotives (when three years later they would start trying to stick Caprotti valve gear on most anything in their product offerings) is an indication that perceived maintenance concerns outweighed periodic firebox replacement of cheaper staybolted-plate construction.  Some of the potential circulation issues that were not overtly recognized in the Baldwin detail design might have become severe with increasing firing level, in a way less critical in 'forced' staybolted boiler construction.

It is interesting to compare the details of the Baldwin approach with the later series of Emerson watertube boxes, which appear to have been serviceable even on a somewhat penurious railroad.

Now, in my humble opinion, natural circulation in a locomotive radiant section can often be 'gainfully improved on', even by methods as simple as used in the Cunningham circulator.  Using the kind of forced circulation seen in a Lamont boiler, for example -- where the waterwall in the radiant section is provided as a relatively low-flow-restriction set of tubes, through which water is forced at about 6x steam demand, and active steam separation is provided -- a relatively good uptake of radiant heat can be accommodated with minimal DNB or hotspot concerns, but with minimum effective head issues around the circulating pumps (which are arranged to run without cavitation only in overcritical water and hence have no particular pressure head; the principal resistance being hydrodynamic, amounting to no more than a few effective psi).

Note that this is NOT a 'once-through' arrangement; the water recovered in the separators is used as the source for the circulation, and adequate 'hot-well' reserve is provided to ensure the circulation is not interrupted.  This was of course much easier to provide in marine installations, but with some care about how feedwater and economizer systems are managed, I see no showstopping difficulty in applying it to locomotives up to the scale that water rate controls any further horsepower increase in a single unit -- around 7900 peak hp in practice in the late '40s, and not really much greater now.

[IA and eastern]

What would be the right size cylinders on this locomotive. Gary

[Overmod]

Read through the references at the following page:

http://www.cwrr.com/Lounge/Reference/baldwin/baldwin.html

Note the long stroke for the comparatively small drivers; balancing is facilitated by the three-cylinder arrangement.

http://www.cwrr.com/Lounge/Reference/baldwin/fig13.gif

http://www.cwrr.com/Lounge/Reference/baldwin/fig13a.gif

 Here is the graph of expansion ratios (for a conservative speed):

http://www.cwrr.com/Lounge/Reference/baldwin/fig42.gif

"The cylinders were designed to do equal work up to a speed of about 22mph, above which, as the tests verify, the inside engine is relieved with increasing speed"

Note the implications of Fry's observation, at the end, that control of the locomotive is often optimized by throttling.