Duplex Steam Locomotive / Steam discussion

[Overmod]

Thanks, gentlemen.

(I confess to being somewhat astounded that PRR would run up to 115mph in a basically uncontrolled environment on live track, with a 70" drivered locomotive!!!)

I'd like to address an earlier point regarding how valuable all the 'late steam' innovations actually were. W.W.Stewart, discussing the NZR Garratts, says this (which I think basically addresses the whole general subject...)

"A large number of innovations ... were incorporated into this design, and at the time of the Garratts' arrival, a Junior Engineer (who later rose to be a District Mechanical Engineer) was instructed by Lynde [the CME responsible for the Garratt design] to work out the total of the savings that were claimed to be effected by the manufacturers of the various devices fitted. For instance, 8 per cent to 12 per cent on coal and water was claimed by the use of the exhaust steam injector. The Franklin grease-lubricated axle-boxes were reputed to run several months without lubrication. The [Nicholson] thermic syphons were supposed to save 10 to 12 per cent in fuel consumption because of increased heating surface and greater steaming capacity. It was claimed the stoker could fire coal of all classes more economically than could be done by hand, and so on and so on.

"The junior thoroughly totted up all these wonderful savings that were to be gained by the multitude of fittings, and in due course handed his report in to Lynde. After carefully reading the estimated and, of course, ridiculous result, Lynde rubbed his hands with glee and remarked, 'Good Lord, she will be puffing pound notes out of her chimney!' Alas, it was not to be."

One wonders how much of the actual benefit of many late-steam devices, similarly, was equal to the claims made by supply-company salesmen et al. ...

[Anonymous]

Overmod sayeth: "(I confess to being somewhat astounded that PRR would run up to 115mph in a basically uncontrolled environment on live track, with a 70" drivered locomotive!!!)"

I mentioned earlier that I had talked at length to the Mechanical Department man (Ed Payne) who was with the 610 on the PRR. He gave me a couple of quotes from the first PRR engineer to handle the 610 on the Broadway between Fort Wayne and Chicago (the engine had been put on the train at Crestline).

Payne followed the engineer as he inspected the engine at Fort Wayne; the man looked at the drivers and looked at Payne and said "this engine will never make the time on THIS railroad!"

The engineer got down off the engine to look it over after they arrived at Englewood on time; walked to the front of the engine and turned around and said to Payne "this is the runninest S-- of a B---- I was ever on in my life".

This engineer had experience on T1s, at that time. He couldn't have been talking about top speed, but acceleration and ability to cruise at a speed sufficient to keep the Broadway on time.

FWIW.

Old Timer

[Anonymous]

Yes. I would like to read Crosby's "Last Chance" and would appreciate Trains.com posting it.

Joe Pausner

[Anonymous]

Mr. Pausner:

Crosby's writings were some of the best that ever appeared in TRAINS. After you get finished with "Last Chance" try to find his "Second Engine #28" which, I believe, was in the May 1975 issue.

It tells the story of firing the second K4 on the Broadway out of Chicago when the T1 wasn't available. For a story, it might be better than "Last Chance".

Old Timer

[Overmod]

Odd you should mention "Second Engine No. 28" as I think I was thinking of a phrase from it when posting above about taking a relatively unknown engine all the way up to 115mph. I don't have the issue handy -- but doesn't he say something in there about taking a curve at some speed well over 90mph and 'the engine only seemed to follow the curve in short, sharp jerks" or words to that effect? I thought then, and still think now with a few different reasons, that when you got THAT kind of effect with a rigid-frame steam locomotive (presumably related to the lateral spring compliance in the leading truck?), you were just about begging to lift a flange or see some other dramatic effect ... but the author gave me the firm impression that it was the sort of thing that happened on the PRR when you needed to make time over the road... Seems 'of a piece' with the laconic reports about spring rigging that needs improvement at very high speeds,,, and taking the runninest SOAB as fast as they could get it to run...

[wallyworld]

Running the wheels off a locomotive trying to make up time against the schedule on a flagship run was part of the heroic romance of the rails which in reading these posts do have a common thread of the art of steam driving versus the science of the machine. That was one of the facsinating aspects of John Cosby's first person narritives. Many an engineer could use their ears alone to determine how an engine was performing. I think the steam engineers were a more important part of the equation in those times.There was no computer controls, anti-wheel slip, dynamic brakes etc. I have a great deal of repect for those men who had to crane their necks, putting their faces out in the elements in a driving rain, looking down the barrel of a boiler in bad weather at 90+ miles per hour.

[Murphy Siding]

I'm not really sure on my terminology here, so bear with me: A lot of British steam locomotives had "inside cylinders"(?), between the drive wheels, while the American designs had "outside cylinders"(?) to the outter side of the drive wheels. What would be the difference, and which seemed to be the better way? Thanks

[feltonhill]

Inside cylinders would allow the locomotive to pass a more restrictive load gage as far as width on the lower end is concerned. Probably there some advantages having the piston forces forces within the frames. Would cut down on yawing when the pistons travel in the same direction for 1/4 of the stroke. Some may prefer the esthetics of having the machinery hidden with just the connecting rods visible. I believe the British liked this sort of approach.

On the other hand, don't even mention maintenance!!! Can you imagine trying to keep after all those moving parts stuffed between the frames?

IMO outside cylinders and machinery have more advantages than disadvantage, at least in US service.

[germanium]

QUOTE: Originally posted by feltonhill

IMO outside cylinders and machinery have more advantages than disadvantage, at least in US service.

Not the least of which is that they make more attractive models than inside-cylindered engines.

[Overmod]

Adding one more small point to feltonhill's note -- having inside cylinders restricts the permissible cylinder bore, and makes driving onto anything but the leading driver axle the same kind of interesting mechanical exercise seen in some locomotives with three- and four-cylinder drive. There's also the cost and complexity of providing a cranked axle.

There is a (preserved!) Belgian express locomotive from the 1930s which used inside cylinders, presumably for the reduction in lateral force at high speed with comparatively high piston thrust that's already been mentioned.

I'd note that, absent the use of high-pressure steam and advanced valve gear to allow very early and well-timed cutoff in smaller cylinders, the volumetric restriction imposed by gauge limitation on cylinder bore will radically restrict the size of a locomotive using inside cylinders ... and the costs of generating very high-pressure steam for this application will almost certainly outweigh any gains to be derived from the arrangement.

A potentially-interesting topic here might be the relative location of inside and outside cylinders on locomotives that use both (including where the HP and LP cylinders for compounds are sited).

[dubousquetaire]

Like all mechanical solutions inside cylinders solved some problems and created others, the size of the inboard cylinders was an issue. The Nord railroad in France tried a few unconventional solutions one on its 1911 Baltic designed by Du Bousquet which preceded Hudsons by quite a few years used one cylinder before the other to stay between the frames and yet increase the diameter on the LP cylinders both had extended piston rods for balance. Later Marc De caso designed his 3120 pacifics with a cast Cylinder block bolted to the frame in front of the HP cylinders between which was reinforced box like caisson, and which was wider than the frame; but then all it had to hold was the frontbuffer beam. This permited to make two inside cylinders whose diameter was greater than the width of the frames. All of these where De Glehn -Du bousquet type 4 cyl Compounds with divide drive.  This provided the same advantages that were saught after by the duplex design in U S practice later and could be balanced so that the engines did not tend to tear themselves appart. In america where axle loads of over Twenty tons where common this may not have been perceived as an advantage (parts could be beefed up) but in France where axle loads had a hard time to reach 20 tons per axle, this was a definite advantage. Contrarilly to what is thought usually, because of these and many other advantages of compound working these engines where economical to maintain. Considering the accessibility for maintenance one should read J.Van Riemsdjik excellent book on the history of compounds.  There remained the safety issue : One was not proud when he had to get inside the frames to work on an engine stored in a yard - if ever there was a rough shunt.  But then a main rod could easely be carried by two whereas on a two cylinder simple it was a lot heavier.