The A4 “Pacifics”: The Fastest Steam Trains in History

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with coal and water for the historic event the futuristic looking locomotive tipped the scales at a whopping 165 tons not counting the weight of the six coaches and dynamometer car behind it the latter of which would determine how fast the train was traveling and how much power its engine was producing then reacting to a rush of superheated steam from the boiler three massive cylinders measuring 18 and a half inches across and 26 inches from top to bottom located deep inside the train's mechanical bowels began thumping methodically emitting intermittent puffs of smoke and steam from its dual exhaust stacks and abundant pressure release valves the trains suddenly lurched to life as wide-eyed spectators looked on with anticipation slowly at first the mighty machine steadily gained speed heading south toward london more than 280 miles away as pressure rose towards the boiler's maximum limit of 250 pounds per square inch the cylinders increased speed until at full bore they were producing more than 2 400 horsepower this was enough to ultimately propel the train past 126 miles per hour albeit for less than one minute on a lonely stretch of track just south of grantham the impressive feat and new world record surpassed the previous mark set by the german steamer br05022 which did 124 miles per hour the previous year now more than 80 years later the record set by the english steam locomotive still stands [Music] known collectively as a4 pacific the attractive powerful and revolutionary class of steam locomotives with the brainchild of sir herbert nigel griesley as britain's preeminent locomotive designer greasy ultimately rose to become chief mechanical engineer at the london and northeastern railway however despite the record-breaking run by a state-of-the-art machine grisly remained ever humble politely reminding everyone that his train had only been capable of maintaining that impressive speed for just a few short seconds data from the dynamometer did prove that a new record had been set but some claimed that it shouldn't have stood at all because at the time griezly's mallard had been on a downward slope in addition its engine had been running at a speed at which it was never meant to operate whereas the german train had been on level ground purportedly with more oomph left under the hood when it set the previous record on the other hand the german machine only weighed 197 tons compared to mallard's gross weight of 240 tons although the original plan had called for the mallard to carry on to london after breaking the record a bearing in the lower end of the center cylinder became so hot that it partially melted prompting an unscheduled stop at peterborough for repairs this issue highlighted a number of serious design and mechanical problems including poor cylinder alignment and inadequate tolerances between vital engine components the result of which was that the center cylinder reciprocated more rapidly did more work and generated more heat than the ones on either side of it these and other issues would be addressed and corrected in later models but controversy national pride and technical jargon aside the ballad's record stood and the event ushered in a new era of ultra-fast commercial passenger services between major cities in england and scotland however greasy wasn't one to rest on his laurels and immediately afterward he and his seasoned team of engineers and drivers set out to up the ante yet again they theorized that under the right conditions 130 miles per hour was possible and that had mallard had not to slow down slightly while passing the rail junction at essendine they may have hit it on the first attempt with the outbreak of war in 1939 however the brash plans took a back seat to far more pressing matters [Music] featuring stunning art deco inspired styling huge boilers and tiny cabin windows barely larger than a man's face at least in hard railroad circles a4s were often referred to as 462s for their unique wheel configurations pioneered by grizzly just a few years before under the white running gear classification system the numbers 4 6 and 2 represent the position of the a4's wheels in this case four unpowered wheels on two axes up front six powered wheels on three axes in the middle and two trailing wheels on one axle in the rear in photographs of a4s it appears as though there were eight more wheels four on either side in the rear of the unit behind the crew compartment however these were actually on the coal car or tender which wasn't technically part of the power unit itself though considering their identical paint schemes and the narrow gap between them it was difficult to tell where one stopped and the other started much of griesley's design inspiration came from a trip taken to germany in 1933 during which he'd been impressed by a new class of diesel locomotives known collectively as flying hamburgers not for their resemblance to the popular food but because they were fast and primarily operated in and around hamburg for a time the lner actually considered purchasing german diesel trains for mainline news between london and newcastle after all diesel's more efficient but though they produced far less horsepower they didn't have multi-thousand gallon boilers prone to catastrophic explosions due to rust and stress fractures however because the technology hadn't been fully developed reliability was a constant concern and the initial capital investment would have been prohibitively expensive thankfully for grizzly these drawbacks definitely worked in his favor he knew that steam was still a viable alternative and that with additional development he could produce locomotives that were even faster more reliable and more efficient as such lessons learned from earlier a1 and a3s made them the perfect foundations on which to base the new a4s like a4s in their time both a1 and a3 set a number of speed records themselves originally designed for mainline passenger service with the great northern railway one such record was set by a3 papyrus number 2750 that hit 108 miles per hour just a few years before another the silver link later hit 112 miles per hour during a press event held to publicize this introduction to the fleet like their predecessors a4 pacifics were manufactured at el nino's doncaster works but though griezly based his new design largely on his own previous locomotives a number of elements were borrowed from the new breed of trains then being introduced in the united states namely the k-4s developed for the american peninsula railroad by the american lotomotive company alco incorporating a variety of new concepts and design features grassley's a4s would operate under higher boiler pressure and have larger fireboxes and combustion chambers and perhaps even more importantly the consumption of both water and coal were significantly reduced making the trains even more economical another new feature that significantly improved efficiency was the kill chap double chimney the first of which had been installed just before mallard's record run in march of 1938. without this new double exhaust system it's unlikely that the mallet would have reached the speed it did but ironically cost-conscious company executives almost didn't allow it to be installed in the first place because the cost of conversion was just so high in the end they relented and after a brief break-in period it was determined that the exhaust system alone not only increased power but reduced coal consumption by as much as seven pounds per mile not surprisingly many existing locomotives were retrofitted with double chimneys and the new units had them installed at the factory another area in which a falls outside most of their competitors was aerodynamics featuring streamlined metal skirts or violences that covered nearly the entire train only the wheels and running gear were exposed in fact a4s were among the first locomotives with bodies that acted as large airfoils that cut through the air much like the fuselages of airplanes on the downside balancers were expensive to install and maintain made maintenance more difficult and decreased driver visibility as a result they were often removed especially on trains that operated at lower speeds where aerodynamics weren't so important [Music] apollos entered service with the eleni art to power the silver jubilee passenger trains that ran dedicated routes between london king's cross railway station and newcastle since most of the trains were manufactured in 1935 the year of king george v 25th year silver jubilee they were painted silver throughout and took the name to commemorate the historic event each train was originally about 460 feet long and consisted of seven coach cars that together with the locomotive weighed approximately 380 tons though additional cars were added but later nearly doubled that gross weight but though a4s were more than capable of sustained speeds in excess of 100 miles per hour they typically operated much more slowly though english steam or diesel locomotive before or since has matched the a4's top end performance but despite operating primarily on the railroad's east coast mainline which was especially suited to high speeds going that fast just wasn't safe or economical higher speeds not only caused increased wear and tear on the various components but increased power output meant that overstressed engines burned through far more coal average speeds generally hovered around 65 miles per hour and the 285 mile runs between london and newcastle took between four and four and a half hours edge of power was generally calculated mathematically using factors like speed gross weight and grade under normal operating conditions the a4's three-cylinder steam engines produced about 2200 horsepower at this time this was the highest output achieved by any english locomotive though on some occasions when conditions were optimal they were capable of producing nearly 2 500 horsepower this latter figure was calculated in the early 1960s when the mallard hauled 11 coach cars grossing nearly 400 tons up stoke bank at a sustained speed of nearly 80 bars per hour surprisingly this colossal feat actually required more power and tractive effort than the world record run in 1938 by comparison america's big boy steam-powered locomotives cracked out nearly 6000 horsepower and are capable of hauling loads in excess of 3 600 tons though even on level ground they rarely exceeded 70 miles per hour during the battle of britain much of england's commercial rail service was temporarily suspended because slow-moving trains make relatively easy targets and because vital resources like coal and steel were in greater demand elsewhere one a4 that was being stored in what's now the national railway museum in york took a direct hit from a german bomb in late april of 1942 after which it was officially decommissioned and sold for scrap shortly after the cessation of hostilities a4s were once again pressed into unrestricted service and in addition to providing power for the run between london and newcastle a new route to edinburgh and scotland was opened as well the fastest official speed of the post-war era was recorded on may 23 1959 when an a4 hit 112 miles per hour on the downward slope of stoke bank of the 34 a4s built the first four included silver in their names two were named after english colonies and protectorates most were named after birds and the last number 6007 was named after the man who designed them sir nigel griesley [Music] many pacifics remained in service for more than three decades after which they were steadily withdrawn in two stages ending in 1966 or were ultimately replaced by diesel locomotives that were more reliable more fuel efficient and less expensive to operate also known as streaks during their service lives a4s were popular subjects for painters photographers and documentary filmmakers including a1 and a3 models more than 100 pacifics were built two of which were renamed dominion of canada and dwight d eisenhower after the second world war to commemorate contributions made by canada and the united states both were shipped to their new homes overseas after being withdrawn from service with british railways and of those that remained in england a few restored to near original condition as late as 2013 unit 4464 underwent a series of high-speed runs in homage to mallard's record-breaking run in 1938. on that day bitten topped out at 93 miles per hour and though she may have had more in her level heads prevailed and she wasn't pushed any further between 2015 and 2020 union of south africa was the only operational a4 with an up-to-date mainline certificate though she too was withdrawn in 2021 when significant boiler issues were discovered during routine maintenance though there are no longer any a4s fit for service rumor has it that the sir nigel griezly may once again be out on the rails after a complete overhaul that's scheduled for completion in late 2022 so i hope you enjoyed this video if you want to see another video about a giant train this time across the pond in the united states please do click on this video on the screen now and thank you for watching [Music] [Music] you

Channel: Megaprojects

Views: 110,065

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Id: ypuwYtNmOYo

Length: 14min 32sec (872 seconds)

Published: Fri May 20 2022