S2 turbine and Broadway Limited?

[arkady]

Was the PRR's S2 steam turbine locomotive ever assigned -- however briefly -- to the Broadway Limited?

 

[CAZEPHYR]

arkady

Was the PRR's S2 steam turbine locomotive ever assigned -- however briefly -- to the Broadway Limited?

 

There is a picture of the S2 on the Broadway Limited in one of the Pennsy steam books.   It pulled it for sure but I am not sure it was assigned to the train as regular power.

I got to see the S2 sitting in the Chicago Roundhouse in 1948, but the main forward turbine on the right hand side was removed for maintenance.  The 6200 was impressive to see.

CZ

[arkady]

Thanks, CAZephyr.  I envy you for having been able to see the S2 in person.  It was an amazing locomotive.

 

[Train-O]

CZ,

Here:

http://www.crestlineprr.com/s2ebbroadway.jpg.html

My question is, did the S-2 ever haul a freight train??????

 

Ralph

[CAZEPHYR]

Train-O

CZ,

Here:

http://www.crestlineprr.com/s2ebbroadway.jpg.html

My question is, did the S-2 ever haul a freight train??????

 

Ralph

Thanks for the link.    That is one picture I have seen and there are more in the Pennsy books showing the S2.  I doubt if they tried the S2 on a freight unless it was under 1000 tons since the S2 used so much steam starting up that they had trouble keeping water and the steam level to a safe level from what I read.  The Turbines as you probably know are very efficient at high speeds but this application had to start moving from zero rpm.  This requires a great amount of steam to start the turbine moving at a very slow speed until the train was up to 30 mph or so.  There was a video of the S2 starting a train and it was amazing the amount of steam and smoke coming out the stacks.  The video was removed but I got to see it several times about a year ago on youtube.     I would like to have heard that!  

[K4sPRR]

Train-O

CZ,

Here:

http://www.crestlineprr.com/s2ebbroadway.jpg.html

My question is, did the S-2 ever haul a freight train??????

 

Ralph

In the book Pennsy Power on page 240 the author states of the S2, "It ran well on fast passenger and freight trains but was susceptible to diesel competition, cost wise".   With the S2 being such a risky experiment at the time, personally, I doubt much of its early testing was with strictly passenger trains, the risk of the unknown performance and jeopardizing the schedule of a passenger train was not in their thinking.  Like with many of the PRR new kids on the block much of the testing and confidence building was done on the Middle Division slowly graduating to other area's and trains.  In all probability its early tests were with freights and did run such as indicated in Pennsy Power.  Once assigned to Crestline I have found no indication of it running any freight. 

[Train-O]

CZ and K4sPRR,

I thank you both, for your kind replies of interesting information.

Ralph

[Juniatha]

CAZEPHYR

Since you mention to have seen the engine in Crestline :  I have always wondered why the forward turbine got damaged .   In view of that massive steam consumption immediately up with a start , inevitable with using a direct drive , I suspect it could have been a case of water carryover .   While there was no cylinder head to blow out , that didn't mean the notorious 'watermen' among drivers and firemen could happily pursue their habits with no consequences .   If turbine blades were hit by water blows it couldn't have taken long until they had to break .   That would have finished active life of that engine for a management eager to dismiss steam as fast as possible or impossible seeking to save by dieselization with outlandish monsters such as the 'shark nose' ( or 'submarines' as one user has pointed out ) Baldwin Centipedes and the like - no matter what the extra costs .  ( no insult intended - you all know by now I'm an unwavering steam fan )

Regards

= J =

[K4sPRR]

The S2 was out of service 54% of the time from when it was built to June of 1945.  The problems were usually minor and rarely involved the turbine.   In an attempt to remedy the problem(s) a scale model of the S2 was built and observed where it was determined the major problem was due to poor water circulation and pressure drops to as low as 85psi when starting.  This caused warping of the firebox sheets and staybolt breakage which resulted in constant leaking. 

The PRR consdered rebuilding the locomotive with a new firebox and backhead in 1947 and early 1948 when major shop work would be required.   This was ultimately cancelled and the unit placed in storage in 1949.  Other than that the PRR officials were pleased with experiment but that darn ol' diesel thing popped up and costs suddenly came into play. 

[Juniatha]

Hi K4s PRR

 

In my view talking of >> 54 % time out of service << is of questionable meaning .

First of all , in a prototype engine there should be adaptations and improvements made continuously to the locomotive as built – this applies all the more to an engine that should be considered a trial , such as the S2 .   So , there were different kinds of reasons for stopping the loco and different kinds of work jobs to be done – not all the stops were because of break-downs !

Second , what was ‘regular service time’ with a trial engine ?   I feel , actual on the road service on regular trains must be seen as ‘road testing time’ rather than ‘regular service time’ .

In this perspective the value of so much time on road / in shop attains a different meaning , or : shop time could as well mean more improvements applied to the setup of the engine , more road time could – didn’t have to – indicate a more indifferent attitude where the locomotive was simply used as it was , faults included .   In the end , a lower road time factor could have resulted from larger advances made , more knowledge gained and applied and thus pave the road for a future much improved series production of the technology tested – while a larger road time factor with few changes made could mean a dead end development .   Could be – didn’t have to .   As for PRR , so far I haven’t really got an impression they were the ones to tune and improve all that much on engines once they had entered service .

Your mentioning >> poor water circulation << – Could you specify in which sense there was poor circulation ?   As from what I’ve learned , the boiler of this engine was pretty much in line with established boiler design used in big Duplexii where there was no such problem mentioned . ( see remark as to steam turbine consumption further down )

Your mentioning >> pressure drops to as low as 85 psi << – I have read of this problem and small wonder it existed .   A driver , however , who stubbornly continued to push what obviously wouldn’t work until boiler pressure was nearly gone should simply have been pulled off the cab and delegated to fire cleaning duties or other more infamous jobs provided by coal fired steam traction .   Who was to wonder a firebox had to yield by that sort of treating ?   Dropping b p that way meant a lot of latent heat in boiler water was being spent , water temp dropped and so did temp of outer firebox shell while inner firebox was submitted to a sudden surge of high heat load by strong draught involved with high steam consumption – in other words , outer and inner walls were on contradicting temp vectors and that meant a contradicting heat expansion situation – poor staybolts !   By brute stability of its structure , consequences could have been amended with fully welded boiler construction – however this would have meant patching up bad effects while not addressing reasons of a problem .

               Your mentioning >>.. attempt to remedy the problem(s) a scale model .. was built ..<< – Ok , we tend to forget about these engines existed over half a century ago – yet , it was known back then the steam turbine was a great success in ships propulsion since engines of tall deep sea ships run on continuous uniform level of output for days on end .   Further , with ships propulsion a steam turbine never had to make dead slow starts at full pressure from zero rpm like a direct drive turbine in a steam locomotive of the configurations applied in the American , British and German trial engines simply replacing cylinders and drive rods unit with turbine and gear unit – so the very problem of the Maffei , Krupp , Zoelly , Stanier and Baldwin direct drive turbine trial engines never existed in marine applications .

When starting from stand-still , what’s the difference in steam turbine as in contrast to steam piston engine?   Starting a piston engine locomotive , steam was being admitted to cylinders and filled chambers , building up pressure , then waited – with a little more steam filling up for some cooling and condensing , while some lesser or larger fraction of steam found freedom by escaping past valve rings , piston rings and glands – until something moved or yielded , most often pistons started to move as things went about their regular way .   Only then and only to the pace of piston displacement was more steam passing though cylinders , or : in spite of impressive sounding exhaust beats , the amount of steam used by the engine unit was not all that much as long as wheels only began to start slowly . consumption increased as wheels turned faster , there was a certain compensation by shorter cut-off used with higher rpm working to apply expansion of steam in cylinders rather than fresh steam from steam chest for most of the piston stroke .   In contrast , with a turbine steam was already passing continuously through the unit and out through chimney even when the engine was standing still !   That meant , the very moment a driver opened the throttle steam consumption went up .  

If he opened flat out – as I have repeatedly heard and read about the Pennsy hoggers – the very moment he had steam consumption fully up to max .   Sorry , the Stephensonian type of boiler with its staybolted rigid connection of large flat sheet metal plates simply wasn’t fit for that sort of shanghaiing .   On the other hand , this sort of handling clearly caused huge fuel consumption at start and all through low speed range .   That is why I wrote in an earlier post # 6200 as built should have been best on fast , relatively light trains with few stops .   Again , massive looks betrayed the fact this was principally a high speed engine , not a heavy lugger .  

Coming back on the water circulation issue : since steam consumption and with ensuing high draught consequently steam production went from nil to max in no time when starting by that ‘yank-it’ style , clearly water circulation was instantly lacking behind because tons of water inside the boiler could not start to circulate as vividly as they did when everything had settled in a fully heated pace of steam production such as midways up on a long ramp or racing along at top speed on a level stretch .   Little could be done about that – it was really a misfit between steam production unit and steam utilization unit .  

Actual trouble resulting from that situation could have been largely amended by simply starting out more gently and – as I said – using the engine on suited fast through running trains .   The Broadway Ltd might come to mind .

 In a nutshell : The S2 6200 was a powerful and probably quite economic engine at speed – yet at starting , although rarely slipping , she was at least no better than classic piston steam locomotives  – she represented a sheer antitheses to the diesel’s offering where constant motor power output throughout the entire speed range from dead start to maximum speed provided a basically strong starting , flexible power .   Since the railroads had definitely opted for the later type of power , any steam turbine like # 6200 had lost by default when leaving builder’s yard .

Regards

               Juniatha

 

[Piper106a]

As one who has studied steam a long time, I had frequently heard the 'high steam consumption at starting' comment many times, but Juniatha's post greatly clarified what was actually happening. 

Rather than a direct connection between the 'throttle' in the cab and the turbine admission valve, what was needed was some control logic that would have limited the speed of opening of the steam valve, and also limited the opening of that valve at low rail speed and/or low boiler pressure regardless of what the engineer did or did not do.  This would not have been a difficult as young members of board might assume.   Pneumatic control logic was in common use in the chemical industry in the 1940s, and what I have suggested above would not have been difficult at all for this method/time. 

Piper106 .  .  '

[Redwards]

It looks like the Spring 2012 Issue of Classic Trains will feature an article on the S2.

--Reed

[K4sPRR]

Regardless of how the 54% down time is calculated its still too much, even for a steam locomotive.  Generally such statistics did not involve scheduled down time for preventive maintenance but still the calculation is what it is.

The boiler used on the S2 was a conventional firetube type, using a conventional boiler on a turbine was an experiment that resulted in some unexpected problems.  The PRR considered testing another type of turbine locomotive using two sets of turbine/gear drivers.  This would have included a watertube type boiler which the PRR felt would solve the more serious problems of the S2.  A watertube boiler was used by N&W on the Jawn Henry, the PRR speculated early on that this type boiler would increase working pressure.  Unlike the Jawn Henry who's turbine failed (not a real fair comparison as both these engines had different motive systems.  The UP later version had ash erosion problems on the turbine blades.) the PRR turbine and gears held up well.  More pressure and a change of boiler style was the possible need.

I agree there is little difference starting  from a complete stop between a turbine or conventional locomotive, but putting the "pedal to the metal" I feel is a humorous exageration.  No hogger is going to disrespect his fireman like that unless they were feuding.  A capable boiler, who's job is to produce energy faster than its being used, is not going to act in the way the S2 did.  Simply put, the S2 required much more early get up and go,  putting a turbine on a conventional boiler without allowances for such was an error.  One the PRR admittedly realized and would have corrected on round two of the turbine experiment.  Unfortunately it never got off the blue prints.

Looking back while considering today's knowledge can promote some speculation, but at the time I commend the rail lines who in different ways challenged the diesel.  It would have been great to see what would have ultimately resulted.   Keep in mind the PRR experimental attitude, the first K4 was built in 1914 and did not go into full production until 1917, many tweaks working out the bugs.  The Q1 gave them the knowledge that resulted in the Q2.  The result many times was a locomotive that met their needs.

Your comments are well thought, thanks for sharing!!!!  

  

   

 

      

 

[erikem]

Perhaps the most serious problem with the S-2 was that the steam consumption per hour was pretty much a function of tractive effort only, with little change from a dead stop to 70 MPH. Above 70 MPH, the S-2 was more efficient than any PRR piston steamer.  The PRR was considering a low speed forward turbine for better economy at low speeds.

- Erik