Why Weren't Duplex Steam Engines Successful?

foreign most of its existence the way that steam locomote has worked has stayed the same burn a feel to boil water into steam which can then move Pistons connected to side rods to turn the wheels although the Locomo is being produced by the mid 20th century were far removed from their earliest ancestors most designers saw no incentive to break the chain why fix something that wasn't broken to some though steam needed to do better and we go to the ends of the Earth to make them better in that regard the duplex type engine was rather simple in concept but it had the potential of being the best of steam technology or the end of an era [Music] in the 1930s the Pennsylvania Railroad was making great strides in recovering from the Great Depression in some ways though recovery was moving along a little too well with passengers and Freight back on the Move making trains longer and heavier locomotive rosters everywhere were being caught out by the increased workloads in the short term an alternative method to keep the increasing tonnage rolling was the doublehead trains with two locomotives while they wouldn't increase any wear and tear on the rails both engines require two separate Crews and twice the amount of fuel and maintenance which added on to the company's expenses in those days it was not uncommon for named trains like the Broadway limited to be hustled by two k-4 pacifics between Chicago and Harrisburg where electric locomotives would take over they were good engines for their time in the 19 teens and 20s but their strain was starting the show in the 30s this was especially evident with how roughly they rode at high speeds the Baldwin locomotive Works solution was to split the engine's wheelbase in half similar to the tried to intrude articulated locomotives whereas the frames on these types of engines were hinged to allow for flexing around tight curves Baldwin opted to keep the frame rigid and paired the drivers with lighter main rods powered by smaller than average cylinders with these specs following could in theory create a locomotive that offered the same pulling power as typical superpower engines with greater stability at high speeds while putting out no greater wear on the track than its predecessors and could cost less to maintain with its Lighter Valve gear Baldwin Was preparing to build a demonstrator to show off the concept's potential but two railroads beat them to the punch in May 1937 the Baltimore and Ohio produced the world's first duplex locomotive at their own Mount clear shops in Baltimore a class and one number 5600 named George H Emerson named after the chief of Motive Power who brought it to life it was designed with the basic dimensions of a 484 Northern type in mind write down the sharing the same wheelbase of the main drivers this had been done to fit around the Beano's existing curvature which necessitated turning the rear engine unit back to front the 5600 would normally work at the head end of the bno's Premier passenger trains but could just as easily be found in various public events like the New York World's Fair in 1939 also in attendance at the fair was the Pennsylvania Railroads version of the concept built at their own judiata shops in Altoona just that year the class S1 number 6100 boasted an extravagant 6446 wheel Arrangement which brought the engine's total length up to 140 feet the longest locomotive in the world other features included roller bearings for longer smoother running at high speeds circulators to supercharge the firebox's heat lateral motion boxes on the front of each unit to navigate curves and most distinctively it's futuristic wind tunnel tested streamlined shroud shaped up by industrial designer Raymond Lowey though looking impressive as display pieces both duplexes would find it hard to fit in within the real world the bno's 5600 was held back by its rear cylinders which due to the wheelbase had to be made smaller to fit next to the Firebox their location made them vulnerable to getting cold deaths spewed all over them and prone to overheating and premature wear another issue was the Firebox itself an unconventional water tube design by Emerson himself although tested with positive results on prior engines its application on this duplex made for poor insulation and pruned the vibration in this form the 5600 would last in service until 1944 after barely seven years of service and would be scrapped in 1950 the prr's S1 duplex was comparatively simpler in design but also wasn't without fault one particular side effect was weight distribution with the bulk of its 300 ton Mass resting on the pilot and trailing tracks rather than the drivers this made the prr's big engine surprisingly underpowered for its size which led directly to its other main issue at various places along the engines route to and from the World's Fair circuitous detours were needed to counter for tight clearances ground Crews would have to watch carefully as the engine would tiptoe past low obstacles and remove them as needed the 6100 was simply too long and too stiff-legged to comfortably navigate the prr's vast system in the end the S1 was settle into passenger service on just one route between Chicago and Crestline Ohio even then the engine was too long to fit on the turntables at either end points and had to use nearby y's to get facing the right way at either end of the trip it was not uncommon for one or more Wheels to be overcome by the curve's radius and pop off the track and yet with its standardized Firebox design and all of its cylinders facing forward the 6100 was otherwise a reliable free steaming locomotive and would last three years longer in service than the 5600 did generating up to 6 500 horsepower this engine would cruise with 1010 loaded trains at well over 100 miles per hour it's commonly believed that this engine has hit speeds in excess of 120 but these runs were never officially documented to the P company the s-1 had only done well enough to be kept in service but its size and stiff-leggedness dissuaded any more examples of this design being built with all that was learned from this groundbreaking feat the pr met with Baldwin to discuss building the next incarnation in 1940 the railroad placed the order for two distinct prototypes from Baldwin to be classified as t1s the following December however a wrench restored into the works with the United States's entrance into World War II restrictions were placed on manufacturing to prioritize equipment for the military this meant that the war production board put an all-out ban on designing locomotives from the ground up and any and all new Power had to be built on existing designs [Music] the prr not to be deterred from its progress would apply for an exemption of the three railroads that got it the Santa Fe and Western Pacific railroads would be buying ft diesel electrics while the prrr would continue the duplex development rolling out from Baldwin's erecting Hull in Eddystone in the summer of 1942 the numbered 6110 and 611 were a stark contrast from their extravagant and flamboyant predecessor God was a stainless steel trim at the stylish bullet nose replaced by the intimidating shark news appearance also styled by Raymond Lowey both engines were 20 feet shorter than the S1 and produced slightly less power too but the trade-off with these engines was versatility with their shorter wheelbase allowing them to travel much more of the PR's Network and the combat the lower power output the 611 came with the Franklin booster engine not as trailing track which could add 13 500 pounds of Tractive effort when starting a train from a dead stop in due time both of these t1s could be found on the head end of many name trains within the roads Fleet of modernism [Music] meanwhile the Juniata shops were building a duplex of its own this one intended for building fast Freight the first Incarnation was called the q1 and operated with a four six four four wheel arrangement with its rear cylinders facing back to front just like with the beginners duplex this Achilles heel held the q1 back with wheel slip overheating and cold dust interference the design was revised with all cylinders facing forward on a 4-4-6-4 wheel Arrangement only then was the duplex concept's true power unleashed the Q2 rolling out from Juniata in 1944 will be the largest non-articulated locomotive ever built stretching 124 feet from coupler to coupler during testing on the Juliana plane static bed the Q2 racked up nearly 8 000 horsepower which made it the most powerful rigid frame locomotive ever built unlike all other duplexes that came before it the Q2 wasn't equipped with any abstract features or changes it was static design all the way down and that would help the engine and service life as well as the duplex Concept in general by the end of 1944 the prrr had been sold on the duplexes advantages in the following year they would order 50 T ones for passenger service with one half built by Baldwin and the other by Altoona and 25 q2s for moving Freight and with the end of the war in sight these engines were poised to make the standard railroad of the world also the most innovative but the big question about these engines was it all worth it after all the whole point of the duplex concept was to spread out the reciprocating Mass across the engine's wheelbase and improve the ride Comfort at high speeds sure there is more complex mechanics at work but they were meant to contribute to the engine's efficiency the answer would become apparent as the duplexes pressed on in service as striking as they looked the t1s came with some natural setbacks will slip was by far the most prevalent issue which could be traced to its Drive wheels and valve gear not being equalized correctly as a T1 accelerated the engine's weight would shift the rear driver set which would cause the front to lose its grip this happened at any speed the T1 traveled at even at 100 miles per hour or faster on the q2s this was combated by the electromechanical slip control mechanism that would automatically reduce power to whichever engine unit was slipping even so locomotive Crews for finding it hard to cope with this bad habit and so did backshop workers in true standardized fashion the prrr had insisted on using puppet valves on the t1s which although made to be efficient at high speeds also meant that it would take more effort to keep in good condition much more effort than conventional valve gear by contrast the q2's glaring issue wasn't because of abstract features but water consumption despite being equipped with the coast to coast tenders that could hold almost 20 000 gallons of water a typical start to stop bread could only last as long as an hour and a half if the engine was being run hard also with the passage of time nearly all of the q2s would develop leaks in the boiler Barrel seams which is said to have been caused by frame stress this requires specialized up key from Boilermakers making the maintenance Hogs in fact when compared against the railroads War baby the J-1 class 2104s the q2s only produced slightly more power than the J1 but with twice the operating costs throughout the rest of the decade the prrr tried all sorts of adjustments to help the engines fit in better with the fleet like lighting the cylinders to reduce Tractive effort and swapping out the type a puppet valves with type B rotary cams or just conventional wall Sharp's valve gear for fixing problems this big though some Outsider perspective was needed in the winter of 1944 before placing the order for 50 T ones the prr leased a j-class 484 from the Norfolk and Western and tried it out in Revenue Service between Chicago and Crestline prr engineman commented how impressively the Jay held its steam pressure consistently for long distances with speeds as high as 110 and trains as long as 15 cars in fact the only engine that wrote smoother than the J was the S1 6100 would also help the J was a large Firebox gray area that allowed for better steaming capacity even on bad call and their shorter Drive Wheels with large Valves and long piston travel which helped with acceleration and reduce the slipping problem despite the results being in the Jay's favor the prrr Pressed ahead with the large T1 order in the fall of 1946 two of the production duplexes released the Chesapeake and Ohio which was also studying ways to enhance steam technology their feedback on the t1s was actually quite favorable handling the cnos trains with these at high speeds and not slipping as much as they would at home rails their improved performance off of Home rails raises an intriguing question for PR our operating Crews not used to the duplex's operating habits to understand why this might be a pivotal moment it helps to look back at the prr's situation leading up this concept beforehand the newest theme engines on the prr were the K4 pacifics built as recently as 1928 the operating Department had a habit of getting as much power out of these engines as they could which often resulted in coupling up the trains they weren't designed for if a K4 was rated for 10 cars it was given 12. similarly if an i1 S8 decapi was rated for 2 000 tons it went out with 2400. operating Crews were known for beating The Living Daylights out of their engines if it meant getting as much as they could out of them in order to get from point A to B as the country slipped into the Great Depression the prr put its focus on electrifying parts of its Network particularly the Northeast Corridor between New York and Washington DC following its completion in 1935 the catenary wires braced Westward to Harrisburg and there were plans to someday extend them all the way to Pittsburgh negating the need for investing in new steam locomotives but as the economy recovered trains were becoming longer and heavier than what 1K 4 was capable of and the grand electrification scheme was becoming unreachable by the time double-headed k4s were becoming the norm World War II was on the rise and traffic levels were projected to intensify even more the prr decided that a radical new innovation was the way forward when the duplexes arrived they were unlike anything Crews had operated before they found them phenomenal for their speed and power output especially for making up time across the Flatlands attractive effort and horsepower ratings through the roof they were quite the leap from the comparatively dainty pacifics that came before them if the engineer pulled the k4's throttle by a certain amount the K4 would get up and go as expected but if the same engineer pulled the t1's throttle by the same amount much more power would go to the cylinders and the wheels would slip in this context the wheel slip issue can be traced to applying Power by Instinct and not necessity if too much power was applied the wheel slip could get uncontrollable while the prr report its efforts into the duplex program other railroads and Builders press the head with the Trident intrude 484 Northern type and came up with some truly great designs that could outperform the duplexes with none of the specialized treatments some of these engines would serve their railroads well into the Twilight of the steam era Baldwin had tried to market the concept to other railroads before the war but there will be no other buyers for the prrr who was hoped to be an extension of the steam era ended up putting an end to it by 1947 all development for steam was halted and the 10-year process of dieselization began within five years all the duplexes would be off the roster lingering in scrap yards until 1956. the duplex concept has been the center of Fascination for steam fans ever since while their legacy is often associated with high maintenance costs and features that prove to be too much to handle many see this type of engine as being ahead of its time and speculate what might have been had diesels not intervened in 2014 one group began its quest to put those claims to the test the prr T1 locomotive trust has been working to build an all-new duplex from the ground up by using the latest features and Technologies to correct the t1's flaws when completed prr number 5550 would be the United States's largest new build locomotive with the full intention of operating it for the public if successful even in limited capacity the duplex concept might hold some redeeming qualities yet [Music] foreign [Music] [Music]

Channel: High Iron

Views: 1,475,826

Keywords: trains, rail, railroad, steam trains galore, train, steam, steam train, Pennsylvania Railroad, pennsylvania railroad steam locomotives, t1 duplex, prr 6100, PRR S1, prr s1 duplex, prr t1, prr q2, Horseshoe Curve, PRR K4, passenger train, streamline, Pennsylvania, freight train, streamlined, engineering

Id: 2RusRdlE-gg

Length: 20min 52sec (1252 seconds)

Published: Wed Dec 07 2022