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I seem to recall that towards the end of steam production there was a small movement towards poppet valves.

I think the Pennsy used them on some of their stuff the S1, T1 and Q2 duplexes maybe? Anybody know much about these creatures? Pennsy used the device on atleast 1 K4s and a couple of T1's. The engineer shortens the cutoff by shortening the valve travel. Dunno whether the exhaust opening is also constricting. With conventional gears, shorter cutoff means earlier compression. How much of a problem is that? No idea. Around the PRR tried poppets on a K-4, along with some other improvements, and got a dramatic increase in high-speed power.

But NY Central's poppet didn't outpull its piston counterparts by much at 80 mph, and not at all at So it's sounding like the PRR did a lot with poppet valves which makes sense as they kind of went their own way with steam anyways. Did many railroads experiment with poppet valving? It's also seeming like an eastern thing based on the references I've noted so far.

Were the eastern roads more "pioneering" when it came to steam development, or were there other reasons that most of the poppet references have been eastern roads? Unless I'm mistaken, all of the T1's had rotary cam poppet valves. I have heard the T1's were often sent on the road with one set of sanders inoperational and when starting a heavy train they required both sand and a light touch on the throttle to prevent them from slipping.

They had oscillating cam gear, better known as Type A. Thanks for the prompt correction. Did the oscillating cams actuate poppet or conventional steam valves?

It's also interesting to learn about the T1a. Any idea why and when in the T1 life cycle early or late will suffice it was fitted with Walschaert gear?

My guess would be that it was an attempt to overcome the maintenance problems that I have heard plagued the cam actuated valving. Another question that has always puzzled me is how was the cutoff varied with the cam drives, both oscillating and rotary?

Broadway Limited T1 PRR Duplex 4-4-4-4 Paragon 2 in HO - Take 2

Your reply demonstrates one of the great values of this Forum - specifically to correct long held beliefs that we sometimes have come to accept as valid truths.

On the T1, both the oscillating cam and rotary cam drives were mechanical. The valve drive cam moved through a small arc but did not fully rotate degrees. As the name suggests, on rotary cam drive, the cam operated more like those in IC engines, i. I know it was done, but don't know exactly how. I'll keep looking for a good explanation. Some early poppet valve gear were steam actuated, but I never heard that they were successful, at least in the US environment.Did remain equipped with poppet valves for the remainder of its service life, and was that life shorter than its classmates which were not converted?

Alex Schneider. In the cylinder detail it surely appears to have been cast. I was half expecting that it would have been a weldment, a la' some of the M cylinders, as seen in the Hagley pix. We have a significant file on that locomotive at the Archives, and have provided some of that content to the T1 trust.

prr t1 valve gear

WWII shortages of manpower and material during the construction of that locomotive delayed its completion until after the production T1's had been ordered. One can only wonder if that locomotive had been completed quickly, and validated the rotary cam design in time for T1 production, that the T1's reputation may have been quite different.

The T1 Trust may be able to prove that Dave Evans. If you or anyone else has photos of the three engines at the end of their lives, I'd be very interested. I'm going to go by the order that the engines were converted to run with poppet valves.

K4s built by Juniata, construction number in August Initially equipped with Franklin Type A poppet vavles in Septemberwith a weight increase tolbs. Edson does not have a not about poppet valves for this engine unlike and To me, this engine's fate is the most enigmatic of the three. I have not seen an explanation of how the Jones poppet valves worked or how long they lasted on K4s Out of the three engines, I think K4s got her conventional cylinders back before retirement based on a look at entries in the MP please see below.

I realize that there's a difference between the "dropped from the roster date" category and the "sold for scrap" category," but I think it is at least possible that was on PRR's roster after and were dropped in I would be very interested in when and last ran in revenue service.

This Flickr shot seems to show a date of June 8, and shows what looks like a freshly converted With marker lights on the pilot deck, I'll estimate this photo dates between and Edson's note a about states that she got Franklin Type B poppet valves in Decemberwith an increase in weight tolbs.

prr t1 valve gear

If the December date is accurate, this is early on in the T1 production run. Picture below shows K4s circa Pending a late s or early s photo ofI'll speculate that she was converted back to Walschaerts valve gear and conventional cylinders at some point during WWII or at least prior to the MP Doug, We have some files on poppet valves at Lewistown - They confirm that did have the rotary cam based poppet valves Franklin type B install in Decemberusing a new, welded cylinder assembly.

The correspondence we have between the PRR and Franklin shows several early teething problems, which appear to have been successfully resolved. The last exchange I have found so far is from the end of May,after suffered from a left piston failure.

At that point 17 months the engine had logged aboutmiles with the poppet valves. That works out to about 6, miles per month - per day. Although the locomotive was supposed to be overhauled in Altoona when the new cylinder and poppet valves were installed, the forces out on the west end of the system where the locomotive was senthad a lot of problems initially - the drive wheel tires had to be turned, pins replaced, and the wheels rebalanced. Plus the link pin to the tender was badly worn.

Once those problems were fixed, the locomotive was described as running as well aswith the exception of some gear drive problems and some cam problems both resolved. If the photo's date is correct, then clearly the locomotive was restored to service after the piston failure. A letter from July reports that had loggedmiles since Maya much lower monthly rate thanbut then we know that was the subject of extensive testing to include in the test plant and on-the-road dyno testsand that other new features beyond the poppet valves were also tested on that locomotive.

And that the poppet valves themselves had some early problems, which did not occur on Moderators: slide rulesTypewriters. Privacy Terms. Quick links. Pennsylvania RR T-1 modification?

Poppet Valves

Discussion of steam locomotives from all manufacturers and railroads. It would seem that this -- if feasible -- would have done much to alleviate their wheelslip problems. A similar design idea was incorporated in the s proposal for the "ACE" modern steam locomotive. Does anyone know more about this proposal? How far the design work went? And what would it have been called in Whyte notation? Somehow no longer seems appropriate, but wouldn't have looked exactly like a conventional either!

This would have made a locomotive type of complex character even more demanding and more complex. Now, while the Duplex concept was created in order to use more than two cylinders on wheel sets in one rigid frame, yet to avoid crank axles, it would have been a contradiction by itself to install two crank axles with two cranks each as a means to amend Duplex type difficulties! If from the beginning the wheel arrangement would have been left instead of and a four cylinder layout had been used unusual in America of coursethen there would have been need for but one crank axle with two cranks.

The forces acting on such 'inside coupling crank axles' would - under normal conditions of adhesion - be much smaller than the piston forces and main rod mass acceleration forces imposed on the crank axle of a four cylinder type of engine with two outside plus two inside cylinders.

However it could not be relied upon such 'regular' conditions would always prevail. On the contrary, the provision of those 'inside coupling crank axles' was to deal with non-regular conditions, i.

Such conditions could impose extremely high forces on these crank axles. Just imagine the engine loosing adhesion on a 'greaser' point enough to produce a slip.

prr t1 valve gear

Then the first drive set reaches clean, dry rails again and wants to stop slipping - but the second wants to continue. It now rests entirely on those inside cranks to stop the second drive set with all its mass inertia of wheel sets and rods! This can produce extremely high forces working on the seats of the wheels on those crank axles, wanting to turn the wheels on their axles.

The axles and cranks themselves also are under high stresses from these forces. The sort of coupling attained by such a 'detour coupling' is not a very rigid one. Just think of the way a piston force produced by one of the rear set of cylinders has to go to reach wheels of the first drive set: The second set of cylinders drive to the fourth driven axle.

From there to third the piston force is transmitted directly via coupling rod on the same main pin. From third to second driven axle it is via pin of third axle, wheel, axle, inside crank, then via coupling rod to inside crank of second driven axle, its wheel and pin to outside coupling rod to pin of first driven axle. There is a lot of flexion in that!It was designed to demonstrate the advantages of duplex drives espoused by Baldwin Chief Engineer Ralph P. It was the longest and heaviest rigid frame reciprocating steam locomotive that was ever built.

The S1 had a unique wheel arrangementmeaning that it had two pairs of cylinderseach driving two pairs of driving wheels. To achieve stability at fast passenger train speeds above mpharticulation was not used. The S1 was completed on January 31,at Altoona shop, and was numbered The problem of wheel slippage, along with a wheelbase that was too long for many of the rail line's curves, limited the S1's usefulness.

No further S1 models were built as focus shifted to the much smaller but more practical class T1 in June Design of the T1 and the S1 occurred concurrently, however, the S1 was the first produced. As early as Junethe management of Pennsylvania Railroad decided to build a new passenger locomotive to replace its aging K4s locomotives.

They also hoped that the new S1 steam locomotive would have a performance equal to their GG1 electric engine and would be capable of hauling a 1,ton passenger train at mph. Kiesel, J. Duer and W. Baldwin presented several and designs made for other railroads. However, PRR rejected the design in favor of a rigid frame duplex and asked Baldwin to consider the wheel arrangement PRR preferred and asked Baldwin to consider a passenger version with 80" drivers and a freight version with 72" drivers.

However, the cooperation between PRR and Baldwin, which proceeded without signing any agreement or contract, for the development of the new high-speed duplex engine didn't go smoothly. The design started with a duplex. After various details were discussed and finalized, it became necessary to make changes that substantially increased the locomotive's weight.

By the time the plans were finalized and approved it had evolved into a The benefits of a duplex design included lighter machinery, shorter cylinder stroke, less wear, lower piston thrust, smaller more efficient cylinders, and a more stable frame than an articulated underframe, also, no hinged connection had to be maintained.

Baldwin's chief engineer believed that the 8-coupled, two-cylinder locomotives of the time were at or near practical limits in terms of steam flow, cylinder efficiency could be improved at high speed by getting the same power from four smaller cylinders with proportionately larger valves. The S1 was the largest passenger locomotive ever constructed, the cast steel locomotive bed plate made by General Steel Castings was the largest single-piece casting ever made for a locomotive.

Unlike other experimental duplex engines like PRR's Class Q1there were no flangeless wheels or blind drivers adopted on S1. PRR believed that the large diameter drivers could increase the tractive effort without causing undue slipping.

Symesa senior official who against the idea of duplex engine in later years, approved the extension of stall no. The stall had a connection at the back because the S1 could only be turned on a wye, but not on the roundhouse's turntable. Timken roller bearings were equipped on the crosshead pins, all engine trucks, and drive axles as well as the tender trucks.

Besides, the lightweight reciprocating parts were manufactured by Timken High Dynamic Steel and designed by Timken engineers.The Pennsylvania Railroad 's 52 T1 class duplex-drive steam locomotivesintroduced in 2 prototypes and 50 productionwere the last steam locomotives built for the PRR and arguably its most controversial. They were ambitious, technologically sophisticated, powerful, fast and distinctively streamlined by Raymond Loewy.

However, they were also prone to wheelslip both when starting and at speed, complicated to maintain and expensive to run. An article appearing in a issue of the Pennsylvania Railroad Technical and Historical Society Magazine showed that inadequate training for engineers transitioning to the T1 may have led to excessive throttle applications, resulting in driver slippage.

In the production fleet the PRR equalized the engine truck with the front engine and the trailing truck with the rear engine, which helped to solve the wheelslip problem. Before the T1, the last production express passenger engine the PRR had produced was the K4s ofproduced until After that, the PRR's attention switched to electrification and the production of electric locomotives ; apparently, the railroad decided that it did not need more steam locomotives. But the deficiencies of the K4s became more evident during the s.

They were fine locomotives, but as train lengths increased they proved to be underpowered; double headed K4s locomotives became the norm on many trains. The railroad had many locomotives available, but paying two crews on two locomotives per train was expensive. Meanwhile, other railroads were leaping ahead, developing increasingly powerful passenger train locomotives. Rival New York Central built Hudsonswhile other roads developed passenger "Mountain" types and then "Northern" designs.

The PRR's steam power began to look outdated. The PRR began to develop steam locomotives again in the mid-to-late s, but with a difference. Where previous PRR locomotive policy had been conservative, new radical designs took hold. Designers from the Baldwin Locomotive Worksthe PRR's longtime development partner, were eager to prove the viability of steam in the face of new competition from Diesel-electric locomotives.

They persuaded the railroad to adopt Baldwin's latest idea: the duplex locomotive. This split the locomotive's driving wheels into two sets, each with its own pair of cylinders and rods. Until then, the only locomotives with two sets of drivers were articulated locomotivesbut the duplex used one rigid frame. In a duplex design cylinders could be smaller, and the weight of side and main rods could be drastically reduced.

Given that the movement of the main rod could not be fully balanced, the duplex design would reduce the "hammer blow" on the track. The lower reciprocating mass meant that higher speeds could be achieved. Use of poppet valves also increased the speed because they gave very accurately timed delivery of steam to the cylinders.

The first PRR duplex was the single experimental S1 of It was powerful and managed to reach Its performance encouraged the PRR continued to develop duplex steam locomotives. The S1 was built unnecessarily large for her exhibition at the New York World's Fair until October ; therefore its turning radius prohibited it from operating over most of the PRR network.

The design reduced driving set traction to the point that it was especially prone to wheel slip [ citation needed ] ; thus only one Class S1 was built. The PRR returned to Baldwin to develop a duplex design fit for series production. Baldwin's chief designer, Ralph P. Johnson, was responsible for the mechanical aspects of the new T1 class. The last production T1 entered service on August 27, Due to their complexity relative to other steam locomotive designs, T1s were known to be difficult to maintain.

The price paid for such speed was higher maintenance costs and increased failures in service. The T-1 was so powerful that violent wheel slip over a wide speed range could occur if the throttle was not handled carefully by the engineer. Loss of driver traction at high speeds, especially when the T1 was under heavy load while ascending grades, caused damage to the poppet valves.

They were described as "free steaming," meaning they could maintain boiler pressure regardless of throttle setting.Nothing is more fairly distributed than common sense: no one thinks he needs more of it than he already has. Our community is FREE to join. To participate you must either login or register for an account. Connect with us! Sign up for our email newsletter. Login or Register Customer Service. COM Enter keywords or a search phrase below: Search.

Franklin B rotary cam poppet valves views. Order Ascending Order Descending. Member since May 16 posts. Posted by natelord on Tuesday, April 13, AM. Incidently, how did the performance of that class compare with the pre-war L-2s? Member since January 3, posts. No, there were a small number of other locomotives fitted with Franklin Type B rotary cam poppet valve gear.

Member since February From: Muncie, Indiana Boy, It was a guest here a half dozen times or so in the I suppose late 80's What a shame it travels no more. Most varieties of poppet valves resulted in improved performance when they were installed. The downside was that the locomotives with poppet valves wound up being oddballs on the roster with the usual poor maintenance as a result. The daily commute is part of everyday life but I get two rides a day out of it.

Member since Aprilposts.

Pennsylvania Railroad class T1

I understand the engine is still around, after a sort; it's a rusting hulk on Texas State RR the last I heard. The was later renumberedif I recall Reply Edit. Posted by wallyworld on Thursday, April 15, AM. However, some felt that since the engine was a design that the actual improvements in performance were due to the redesign of steam passages and a reconfigured superheater.

The Type B was installed on K4s in and later retrofitted on in On pageT-1 is shown with external rotary drives for Type B poppet gear "after being involved in a wreck in the St Louis area". The drives are the same as those shown on Also on page is a photo of T-1 with piston valves and Walschaert gear, and even it was thought to be better than the standard T But there is no question that the EMD E-7s were much, much better than the T-1s, and entered traffic about the same time.

Posted by wallyworld on Thursday, April 15, PM. One of my favorite subjects is the Pennsy, especially in the transition era.Privacy Terms. Quick links. The only source I could find on the Net says that "all were scrapped by ", but I find that date rather early in view of the fact that most T1's were not even built until In contrast, all but two of the NYC Niagaras were retired and scrapped in latewith one lasting as long as June, and one S-2 poppet-valve scrapped earlier.

They were shipped west in early '56, but I can't tell you exactly when. This info has appeared in the Keystone over the last nine years or so. This last bunch was a group of Baldwins in the series, and included the T1a Too bad the TEEs were so loaded with aftermarket parts, or perhaps they might have made it to the very end in late ' A couple of K4s and M1s cannot compare. Last edited by DonPevsner on Thu Aug 05, pm, edited 1 time in total.

But when they were sold for scrap they had been out of service for some time. Can anyone say when the T1 were last used in service? One source "Pennsylvania Duplexii" by Brian Reed, says "By the end ofpractiacally the whole fleet of duplexii was laid aside.

Many T-1's were lying at Crestline from August of that year; others were The Q-2s operated longer, a number of them into By scrapping of the production T-1 machines began All T-1s were gone by the end of Perhaps he means that all had been "whitelined," stricken from the roster and and set aside for scrapping by that time.

Alvin Stauffer, in "Pennsy Power," also recounts that T1 were used on Pittsburgh-Greensburg locals, but doesn't I think-- I just gave a very quick glance give actual dates. A lot of their sources were the people actually there, plus info from archival material and such, rather than simply repeating every other author in the popular press. We are now on the way towards an accurate picture of what the TEE actually was, and wasn't.

As far as Mr. Reed's books on American locomotives, I've found much of the info suspect and in some cases, such as the Duplex softcover, completely useless We tend to forget that the PRR TEE was a product of it's times, and was subject to factors which had little to do with the technical merits of the machines themselves.

As it stands, the PRR T1 is one of the two most misunderstood, underrated, and unappreciated American steam locomotives of the mid 20th century. The centerspread painting is nice, though I put no faith in its accuracy as regards color Is anyone actually working on putting such a new book together?

Sign me up for the first copy! This goes back to the late '60s. If someone with a copy of the relevant "Keystone" issue and access to a photocopier wanted to endear themselves to me But there are a couple of things that make me suspect that the folklore about the T-1's problems may have a bit of foundation: 1 One of the report conclusions that's supposed to show the T-1 wasn't so bad was that a "skilled" engineman could keep it from slipping.

Even one of the traditional, "T-1 is as slippery as an eel," sources quoted a report that the T-1 could be kept from slipping with "great skill". This isn't really reassuring. Jet airliners didn't come into general use because Chuck Yeager could land a B safely: they had to be airliners any pilot for a line-haul commercial airline could fly! In other words: does the wording of the "T-1 is o. Sorry, can't source that off-hand: something I've read in the past few days trying to find out what I can.

Now, my impression is that other steam locomotives were best operated at short cut-off when at speed, and that shorter cut-offs made for better fuel economy. So: was the T-1 subject to slippage problems that couold only be mastered by operating in what otherwise would have seemed like an inefficient manner? I'm not trying to be ornery here, but I'd welcome comments.

Heated discussion is a good thing, as long as there is more light than heat!