Jim,
you totally disregard one important factor : steam locomotive design is not done by gambling but by engineering . Engineering again is applied science really , not applied poker .
So , in order to build a new T1 - be it a replica , be it a T1b or even a T2 - is not a matter of applied guestimate but applied engineering , by itself vastly advanced since the days of this historical type of locomotive , again of which much more is known now than was back then before knowing what would be their actual behavior in service . At the time of their introduction the Duplex type held some specific imponderabilities and poppet valve gear was an advanced ambitious proposition . Engineering challenge of both features has since eased significantly .
If we build a new T1 we have two advantages : we can straighten out known compromises in design and we know what to expect .
Further , on the Pennsy the T1 engines had to do hard work 24/7 from the day they had left constructors yard . A replica or a new T1 / T2 will be destined for special travels with a totally different profile of monthly work in ton-miles and attendance applicable to the locomotive .
It is feasible , guys , it's perfectly feasible !
Regards
Juniatha
narig01
*any* type of steam locomotive - if not designed with hoplessly underdimensioned cylinders - *could* run into a slip at start , at low speed hill climbing ( constant high t.e. working ) or at speed due to instant transient loss of adhesion . Varying rail adhesion conditions are an issue in today's modern electric traction - or why should they invest that much thought in better levelling out mass per axle distribution under all conditions of running and ever-improved electronic slip control .
In the Duplex type certain specific aspects of behavior also experienced in SE Mallet types proved to be more pointed and will have to be addressed by design of a new Duplex . What and why this is so I wiill not go into details here or this would become a tolerably long post to read . High speed slip was also experienced with German and French Pacifics and seems to have been known on the NYC, or else why should the Central have arranged those known high speed slippage tests with J-3a class locomotive to investigate what may happen under extreme conditions ?
Narig01 asked a questions about slipping problems with articulateds, and even mentioned UP's 3985 by name. Well guess what, back around 1989 or so Steve Lee of the UP steam program addressed that very question in an article he wrote for "Trains" about running freights with 3985.
The answer was yes, articulateds would slip if not handled correctly. Big Steve said the secret to avoid same was to take it easy on the starts, a long slow pull on the throttle and not "pullin' it like you MEAN it!" An attempted jack-rabbit start would cause the boiler water to surge toward the firebox end reducing weight on the front engine resulting in slips. Nice and easy on the throttle was the way to go.
Overmod refers to an "air assisted swing throttle." I have never heard of this and would appreciate an explanation.
Also, regarding poppet valves, I think a helicopter flight control hydraulic system could be applied to a locomotive with good results. The Sikorsky S-76 uses two very compact and lightweight 3000 psi hydraulic pumps to power the flight control actuators, which adjust the flight path of the rotor blades as they spin. Such a pump could be driven by a small steam turbine. The actuators would directly move the valves with the valve events controlled by the engineer via computer or directly by mechanical linkage.Such a system would be very reliable, nearly maintenance free and robust enough to stand up to railroad operating conditions. What do you think?
The air throttle assist is shown in PRR drawing A436493. This system should provide the same proportional control and positive location that a Franklin Precision reverse does. A competing system from the late '40s was the ThrottleMaster.
There are many forms of servo actuation that can be applied to steam-locomotive valves. For example, air-over-hydraulic servos have a comparatively good history in fast proportional modulation of large valves (and it might be somewhat easier to make arrangements for power air on a locomotive than the very large volume of hydraulic fluid that has to be moved to cycle valves of adequate flow the number of times per minute required for a locomotive at high speed).
Historically, precise hydraulic systems of the kind you describe may have trouble standing up well long-term in typical locomotive operating environments (see the experience, for example, with Meier-Mattern valve gear). I consider the situation to be somewhat less critical on a locomotive with 'typical' non-desmodromic poppet or drop valves (the T1 being an example) tnan on one with piston valves (where position of the valve body may need to be reproduceably assured within 1/32" or better with the valve moving at considerable speed at the moment of admission, with what may be a long overall travel...) But there are still sensor and actuator concerns that I think are substantial.
A greater problem imho is that the effect on the locomotive of valve misposition at high speed can be catastrophic, as there are much greater forces involved than, say, in automotive-size IC engines with 'electronic camshaft' valve actuators. There are different syndromes when different parts of a full-servo valve system go out... few of them particularly pretty. Then there is the matter of road failures that incapacitate the locomotive -- and there are a number of subsystems involved in the full-servo drive you describe which can produce that effect if they fail or suffer 'performance degradation' individually or in complex combination.
That's not to say you can't have servo performance enhancement, only that you'll want to maintain full mechanical integrity of the valve gear and apply the servo action either in the follower mechanism (of a poppet-valve system) or have an auxiliary valve system in parallel that comes into use only at higher speeds (and that is arranged to 'fail safe' to the greatest extent that can be arranged).
Hiawatha A 4-4-2 or F 4-6-4? The former would really be a one-of-a-kind rarety, good for short trains on mostly flat routes. Come to think of it, other than the CP Royal Hudson and one earlier CP example, both very fine locomotives, looks and performance, how many other 4-6-4's are preserved, and how man operational? I think there are two 4-4-2's at the Pennsylvania State RR Museum at Strassburg. Any Atlantics operational?
Hi Dave! No, there's no operational 4-4-2's that I'm aware of. One of the 4-4-2's you mentioned at the Pennsylvania State RR Museum was used by the Strasburg Railroad until ( I think) the mid-1990's. Ultrasonic examination revealed severe firebox erosion so the locomotive was returned to the museum. As the Strasburg was leasing it and didn't own it outright they elected not to repair it. I saw it several years ago and it's in beautiful shape, they didn't return it as a junker, and the impression I got from the museum stafffer I spoke to was there were no hard feelings between the museum and the Strasburg, they realized the Strasburg was under no obligation to repair the firebox. Maybe it'll be restored to operating condition at some point in the future? Anyone's guess.
As an aside, that same ultrasonic unit revealed firebox erosion on so many other Strasburg engines causing them to be immediately pulled from service the Strasburg crew called it "The Death Ray"!
I recall that event. They also had a beautiful PRR D-16 that had to be taking from service and is also on display at the museum. Possibly long in the future, both locos can be restored to operation, but I would not hold my breath.
I Dave! I saw the D-16 at the museum as well, and it was in beautiful shape as well. And I'm with you, I'm not holding my breath waiting for any immediate repair and return to service of either locomotive. Maybe someday, but not soon.
Granted, you can't tell a book by it's cover, but to my untrained eye aside from firebox rebuilding it didn't look like it would take much to put either locomotive in service again.
samfp1943 "...These locomotives sported 80' drivers, "
"...These locomotives sported 80' drivers, "
I recall seeing a T1 sprinting across Ohio when I was a kid ... actually it passed us like we were standing still at 60+ ... but I didn't think the drivers were that large. Maybe 80" would be more likely.
ChuckAllen, TX
daveklepper but I would not hold my breath.
but I would not hold my breath.
In service to you and Firelock, I am holding my breath starting NOW.
GASP!! ....Did it work?
Nah, didn't work. Try it again.
Not a T-1 but somewhat of a clone from the land down under
Never too old to have a happy childhood!
Ah, yes, the SAR 520 class. Good to see 523 out, regrettably she was rather hidden when I was there.
520 has retained her original headlight, which looks much better than the awful sealed beam arrangement that 523 has.
Holy smoke Mr. Balt, that thing's amazing! I'd heard about those Aussie T-1 clones, but this it the first picture I've seen of one. Thanks for posting!
NorthWest520 has retained her original headlight, which looks much better than the awful sealed beam arrangement that 523 has.
Here are two views of 520 with the 'regular' headlight...
Overmod NorthWest 520 has retained her original headlight, which looks much better than the awful sealed beam arrangement that 523 has. Here are two views of 520 with the 'regular' headlight...
NorthWest 520 has retained her original headlight, which looks much better than the awful sealed beam arrangement that 523 has.
What does the X or + sign indicate on the right side of the pilot. Also, what is the O in the left side of the top picture.
The 520 class is a documented copy of the T1 sharknose design. In an article in TRAINS many years ago at the time of the opening of the through standard-gauge transcon route in Australia, the designer of the 520 class stated that he drew on the styling of the T1 when designing the 520 class. Note that it even includes an all-weather cab.
Are 520 and/or 523 operational? Very well worth a trip to Austrailia to ride behind either! Along, of course, with enjoying the Melbourn tram system, now the world's largest, and with those classic W-type trams still iin serivce. Like the Milan Peter Witts, seem like they are eternal.
520 is, with Steamranger. 523 isn't.
BaltACD
What does the X or + sign indicate on the right side of the pilot. Also, what is the O in the left side of the top picture./quote]
From the steam_tech Yahoo group:
The post quote facility appears to be 'down' this morning, so I can't paste in the context.
BaltACD wanted to know what the 'destination sign' on the other side (the circular one that looks a bit like 'Kilroy Was Here') is.
Ivan Marchant noted: "The disc on the right of the picture is what we call the States Emblem or Piping Shrike. Up until the 1960’s, all locos built and operated in South Australia carried that emblem."
520 is operational, with steam ranger. 523 isn't, or isn't yet?
I don't think that there are any plans to fire up 523 at the moment, she is sitting on display at the museum, although not where she is is Balt's picture.
Prof O.
If I may say , it's sentences like this one here [to quote]
>> (see the experience, for example, with Meier-Mattern valve gear) <<
which make people
( who do not necessarily have as big and complete a volume
and content of a library available as you let on to have )
feel cut off from discussion .
I'd appreciate if you could allow yourself to get down
and offer a minimum of a functional explanation
of such items you like to mention all-too laconically
by simply dropping *a name*
- would you mind ?
= J =
Folks ,
could we back up from down-under and again get to speak pensively of pending matters T1 of the good old one-and-only perennial-in-our-mind Pennsylvania RR once roaming hilly land as thickly forrested as Transsylvania - name meaning 'behind the forests' which is why PRR could symbolically also be spelled Pensylvania RR - the railroad in the land of five forests - *gee* -
... although , that would be another story yet .
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