All of the tenders were recycled from other (earlier) models - Long Distance Coal from the 4-6-2 Heavy Pacific, Vanderbilt from the 2-8-2 Heavy Mikado, and Centipede from the 4-8-8-4 Big Boy. The chassis is all-metal and quite hefty. As mentioned previously, the motor is an open-sided Mabuchi (3-pole / skew-wound).Aug 29, 2023 · Get the current price and information for HO Steam Articulated Key Model Imports Challenger Western Pacific 4-6-6-4 by Key Model Imports (KEY) Call 352-292-4116 Mon-Thur 9am-4pm EST Model Search: Union Pacific LEGACY LionMaster Challenger 4-6-6-4 Steam Locomotive #3977 (Greyhound) $ 999.99. Find A Dealer. LionMaster Challengers: The power and excitement of these great locomotives comes with all the features of our scale LEGACY models but in a size runs on O31 curves! This is a Broadway Limited 5821 HO Scale Union Pacific Challenger 4-6-6-4 Excursion Locomotive Oil Tender Black & Graphite Steam Locomotive Paragon3 Sound/DC/DCC Smoke #3985. Industry-Leading Features: NEW Paragon3 Sound & Operation System FEATURING ROLLING THUNDERTM with Authentic Sounds and Prototypical Operation in both DC and DCC environments. Jan 11, 2021 · 6.4 HEMI Common Problems Summary. The 6.4 HEMI first began its life as a crate engine under the name 392 HEMI. In 2011, FCA began using the 392 Apache in production models beginning with the Dodge Challenger SRT8. Since then the engine found its way into many flagship performance models and trucks. Worlds Largest Operating Steam Locomotive, Union Pacific #3985 almost a million pound Challenger class 4-6-6-4 streches her legs at speeds near 70 mph high b...In order to mate the connectors of the drawbar and the tender, place the engine and the tender on the track. Position the tender over the drawbar connector and insert the drawbar pin on the swivel connector into the hole in the drawbar. M.T.H. HO 4-6-6-4 Challenger Steam Engine...The Northern Pacific ordered 21 "Challengers" from the American Locomotive Company in 1936 and took delivery of them during 1936 and 1937. These 4-6-6-4s were designated Class Z-6 and were assigned road numbers 5100 through 5120. They had four 23 x 32 cylinders, 69" drivers, a 250 psi boiler pressure, exerted 104,500 lbs of tractive effort and ...Union Pacific LEGACY 4-6-6-4 Challenger #3985 (BLACK) Challengers for the first time in American Flyer S Gauge. With the advent of diminished locomotive production due to World War II demands and restrictions, many western railroads were hungry for top performing and even more powerful steamers.Union Pacific LionMaster TMCC 4-6-6-4 Challenger #3983 SKU: 6-28077. Union Pacific LionMaster TMCC 4-6-6-4 Challenger #3983. $ 799.95. Find A Dealer. Imagine the world’s largest and most famous steam locomotives running on your layout of O-31 radius track. A fantasy? AMONG THE LATEST in Lionel’s LionMaster line of traditional-sized locomotives is an exceptionally sharp rendering of a Union Pacific-style 4-6-6-4 Challenger, painted and lettered for the Western Maryland Railroad. Although in real life that Appalachian coal hauler used a different style of 4-6-6-4 locomotive, Lionel’s model will probably ...Locking your locomotive into a single operational state 4 Your locomotive’s Odyssey™ System speed control 5 Using your tender-mounted ElectroCoupler in the non-Command environment 6 Your locomotive’s RailSounds system—the basics 7 Experiencing the range of your locomotive’s RailSounds system 8 Notes on RailSounds 8The Union Pacific Railroad took delivery of the very first locomotive with the 4-6-6-4 wheel arrangement in 1936 when it received 15 of them from the American Locomotive Company. These newly named "Challengers" were designated Class CSA-1. In 1937, another 25 ALCO-built "Challengers" were added to the roster. This group, designated Class CSA-2 ...N Scale Key Imports Brass 4-6-6-4 Challenger #3985 Union Pacific UP Bob Gilmore! Opens in a new window or tab. Pre-Owned. $799.99. or Best Offer +$17.10 shippingJun 1, 2013 · The 4-6-6-4 was often used for passenger service, but its main function was carrying heavy, fast freight. It could average speeds of up to 70<br />. The original Challengers had 21" x 32" cylinders, 69" drivers, 255 pounds steam pressure and weighed 566,000 pounds.<br />. All of the tenders were recycled from other (earlier) models - Long Distance Coal from the 4-6-2 Heavy Pacific, Vanderbilt from the 2-8-2 Heavy Mikado, and Centipede from the 4-8-8-4 Big Boy. The chassis is all-metal and quite hefty. As mentioned previously, the motor is an open-sided Mabuchi (3-pole / skew-wound).The 4-6-6-4 was one of the most technologically advanced of its kind with advancements that allowed for both high horsepower and efficient operations. Sadly, however, like the Yellowstones the Challengers had an extremely short lifespan. Upon delivery of the UP’s first Challenger during the mid-1930s all were scrapped in short order ...8 4-6-6-4 Challenger Steam Locomotive Using DCS With DC Power M.T.H.’s revolutionary Digital Command System, or DCS, allows users to control their RailKing One-Gauge locomotives in a command control environment. User’s can remotely access hundreds of features inside each RailKing One-Gauge locomotive with the wireless remote control.These earliest Challengers, some 60 in total, proved their worth on the steep grades of the Wasatch Mountains, showing clearly that the big brute 4-6-6-4 engines had more power and speed than their predecessors. In 1943, twenty five additional ALCO Challengers arrived at the Union Pacific Railroad. These locomotives were initially designed as ... Athearn Genesis Rio Grande 4-6-6-4 Challenger with factory MRC sound pulling a freight through Minturn, CO on my Tennessee Pass line layout. The mighty Union Pacific Challenger 4-6-6-4 is now available for Train Simulator, featuring four exciting and challenging scenarios specially created for the Sherman Hill route. The stiff gradients of the Wasatch Mountains demanded newer, more powerful and efficient locomotives, leading to Union Pacific’s chief engineers to design a 4-6-6-4 ...This HO scale 4-6-6-4 Challenger is a top-notch model and easily the best of Athearn’s Genesis-series steam locomotives. It looks like its famous prototype, and its fine performance is enhanced by sound effects whether running on conventional DC or Digital Command Control (DCC). The story of the Union Pacific Challengers has been told many times.The two ALCO-built 4-6-6-4s received in 1944 were also oil burners and were designated Class Z-8 and given road numbers 910 and 911. These locomotives had (4) 23 x 32 cylinders, 70" drivers, a 260 psi boiler pressure, a tractive effort of 107,000 lbs and weighed 639,000 pounds. The eight SP&S "Challengers" were scrapped in 1960.These pictures, captioned the last challenger were taken June 7 1953. They show engine 1211 leading yet another westbound train out of Cumberland and up Sandpatch with mid-train helper Decapod 1130 and shoving on the rear is 4-8-4 number 1404. Only 1210 and 1211 remained on the roster that June. When talking to WM men there seemed to be only 2 ...The name Challenger was given to steam locomotives with a 4-6-6-4 wheel arrangement. This means that they have four wheels in the leading "pilot" truck, which helps guide the locomotive into curves; two sets of six "driving" wheels, and finally, four "trailing" wheels, which support the rear of the engine and its massive firebox. Part of the April 2016 New Announcements are the CSA-1 and CSA-2 "Original" or "Light" Challengers. These were built in 1936 and 1937 for the Union Pacific Railroad and posses some key spotting features. 8 4-6-6-4 Challenger Steam Locomotive Using DCS With DC Power M.T.H.’s revolutionary Digital Command System, or DCS, allows users to control their RailKing One-Gauge locomotives in a command control environment. User’s can remotely access hundreds of features inside each RailKing One-Gauge locomotive with the wireless remote control.The Union Pacific Railroad took delivery of the very first locomotive with the 4-6-6-4 wheel arrangement in 1936 when it received 15 of them from the American Locomotive Company. These newly named "Challengers" were designated Class CSA-1. In 1937, another 25 ALCO-built "Challengers" were added to the roster. This group, designated Class CSA-2 ... Find many great new & used options and get the best deals for Athearn Genesis HO Union Pacific Challenger 4-6-6-4 3982 Retail at the best online prices at eBay! Free shipping for many products!Jan 11, 2021 · 6.4 HEMI Common Problems Summary. The 6.4 HEMI first began its life as a crate engine under the name 392 HEMI. In 2011, FCA began using the 392 Apache in production models beginning with the Dodge Challenger SRT8. Since then the engine found its way into many flagship performance models and trucks. Page 1 4-6-6-4 Challenger Steam Locomotive OPERATOR’S MANUAL Compatibility This locomotive is capable of operating on AC or DC output power supplies (See page 28 for a complete list of compatible transformers and wiring instructions.) and indoors or outdoors.Get the best deals for lionel 4-6-6-4 challenger at eBay.com. We have a great online selection at the lowest prices with Fast & Free shipping on many items!Aug 29, 2023 · Get the current price and information for HO Steam Articulated Key Model Imports Challenger Western Pacific 4-6-6-4 by Key Model Imports (KEY) Call 352-292-4116 Mon-Thur 9am-4pm EST Model Search: RailKing 4-6-6-4 Challenger Steam Engine Set Up There are a few simple steps you must take before operating this RailKing steamer. 1. You should prime the operating smoke unit with smoke fluid before operating. Add 15-20 drops of smoke fluid through the smokestack, then gently blow into the stack to eliminate any air bubbles in the fluid. See ...These pictures, captioned the last challenger were taken June 7 1953. They show engine 1211 leading yet another westbound train out of Cumberland and up Sandpatch with mid-train helper Decapod 1130 and shoving on the rear is 4-8-4 number 1404. Only 1210 and 1211 remained on the roster that June. When talking to WM men there seemed to be only 2 ...Union Pacific LEGACY 4-6-6-4 Challenger #3985 (BLACK) Challengers for the first time in American Flyer S Gauge. With the advent of diminished locomotive production due to World War II demands and restrictions, many western railroads were hungry for top performing and even more powerful steamers. The name Challenger was given to steam locomotives with a 4-6-6-4 wheel arrangement. This means that they have four wheels in the leading "pilot" truck, which helps guide the locomotive into curves; two sets of six "driving" wheels, and finally, four "trailing" wheels, which support the rear of the engine and its massive firebox.Get the best deals for 4-6-6-4 challenger at eBay.com. We have a great online selection at the lowest prices with Fast & Free shipping on many items!Introducing Broadway Limited Imports' newest addition to our line of N Scale steam locomotives, the Union Pacific Late Challenger.Between 1936 and 1944, the American Locomotive Company (ALCO) constructed a total of 105 Challengers in five classes for theUnion Pacific Railroad No. 3985, also known as 'The Challenger', is a 4664-4 class 4-6-6-4 "Challenger" type articulated steam locomotive built by the American Locomotive Company (ALCO) in July 1943. It was previously owned and operated by the Union Pacific Railroad (UP) in excursion service as part of their heritage fleet, based in Cheyenne, WY, from April 1981 until being taken out of ... Product Spotlight - HO Challenger. M.T.H. Electric Trains has begun shipping its 4-6-6-4 Challenger die-cast HO steam engine. A total of six paint schemes are being offered in standard DC 2- Rail and AC/DC 3-Rail configurations. Each model comes equipped with the most advanced sound and operating system ever installed in HO scale.Product Spotlight - HO Challenger. M.T.H. Electric Trains has begun shipping its 4-6-6-4 Challenger die-cast HO steam engine. A total of six paint schemes are being offered in standard DC 2- Rail and AC/DC 3-Rail configurations. Each model comes equipped with the most advanced sound and operating system ever installed in HO scale. The 4-6-6-4 was one of the most technologically advanced of its kind with advancements that allowed for both high horsepower and efficient operations. Sadly, however, like the Yellowstones the Challengers had an extremely short lifespan. Upon delivery of the UP’s first Challenger during the mid-1930s all were scrapped in short order ... Union Pacific LEGACY 4-6-6-4 Challenger #3985 (BLACK) Challengers for the first time in American Flyer S Gauge. With the advent of diminished locomotive production due to World War II demands and restrictions, many western railroads were hungry for top performing and even more powerful steamers.Get the best deals for lionel 4-6-6-4 challenger at eBay.com. We have a great online selection at the lowest prices with Fast & Free shipping on many items! Union Pacific LEGACY LionMaster Challenger 4-6-6-4 Steam Locomotive #3977 (Greyhound) $ 999.99. Find A Dealer. LionMaster Challengers: The power and excitement of these great locomotives comes with all the features of our scale LEGACY models but in a size runs on O31 curves! The new Trix 4-6-6-4 represents Union Pacific’s final group of Challengers built between 1942 and 1944. For its initial release, Trix’s HO model features an oil tender, and the locomotive is equipped with “wind wings” that aided the prototype in deflecting the exhaust smoke up and away from the cab.Broadway # bro4811. Add To Cart. Wish List. This is the HO Scale 4-6-6-4 CSA-2 Union Pacific Unlettered Post 1947 DCC with Paragon4 model train Steam locomotive from Broadway Limited Imports. (UP Early Challenger). Trust 1000's of Reviews of Hobbylinc. Website security verified by GoDaddy. Industry Leading Loyalty Program. In Whyte notation, a 4-6-6-4 is a railroad steam locomotive that has four leading wheels followed by six coupled driving wheels, a second set of six driving wheels and four trailing wheels. 4-6-6-4's are commonly known as Challengers.8 4-6-6-4 Challenger Steam Locomotive Using DCS With DC Power M.T.H.’s revolutionary Digital Command System, or DCS, allows users to control their RailKing One-Gauge locomotives in a command control environment. User’s can remotely access hundreds of features inside each RailKing One-Gauge locomotive with the wireless remote control.4-6-6-4 "Challenger" Steam Locomotives A-R.com Blog Last revised: May 11, 2023 The Challenger Type, an articulated design (meaning that either one, or both sets of driving wheels pivots to better and more safely negotiate curves), was one of the most successful large steam locomotive designs ever developed.The resulting machine was a winner. UP tested the new 4-6-6-4 engine on a section of track in Utah over the Wahsatch Range. The engineer commented that would be a challenge for any locomotive, and the name stuck. UP officially called the machine the Challenger. A total of 252 Challengers were built between 1935 and 1943. UP received the most, 105.Jan 16, 2017 · Like UP’s earlier 4-6-6-4 Challenger, the Big Boy was articulated to help it negotiate curves and turnouts. On the prototype, the front engine pivoted under the smokebox. On the model, both engines pivot, which is necessary to handle 18″ radius curves, but it creates unrealistic cab overhang. The name Challenger was given to steam locomotives with a 4-6-6-4 wheel arrangement. This means that they have four wheels in the leading "pilot" truck, which helps guide the locomotive into curves; two sets of six "driving" wheels, and finally, four "trailing" wheels, which support the rear of the engine and its massive firebox.The 4-6-6-4 Challenger first appeared on U This is an MTH 70-3016-1 Union Pacific 4-6-6-4 Challenger Steam Engine w/Proto-Sound 2.0, (Yellow Stripes) Cab No. 3980. In the midst of the Great Depression, Union Pacific designed and asked ALCO to build the best high-speed simple articulated engines to grace American rails.Locking your locomotive into a single operational state 4 Your locomotive’s Odyssey™ System speed control 5 Using your tender-mounted ElectroCoupler in the non-Command environment 6 Your locomotive’s RailSounds system—the basics 7 Experiencing the range of your locomotive’s RailSounds system 8 Notes on RailSounds 8Athearn Genesis Rio Grande 4-6-6-4 Challenger with factory MRC sound pulling a freight through Minturn, CO on my Tennessee Pass line layout.O GAUGE PREMIER LINE 4-6-6-4 CHALLENGER BY MTH Price: Features: O-72 operation, die-cast metal construction, can-style motor, ProtoSound 2.0, coil coupler on tender. Pros: Visually stunning, clever new wireless drawbar, superb performance. Cons: Some of the piping and details can be bent by clumsy fingers. Made in the Republic of Korea for MTH ...The 4-6-6-4 Challenger first appeared on U This is an MTH 70-3016-1 Union Pacific 4-6-6-4 Challenger Steam Engine w/Proto-Sound 2.0, (Yellow Stripes) Cab No. 3980. In the midst of the Great Depression, Union Pacific designed and asked ALCO to build the best high-speed simple articulated engines to grace American rails. The 4-6-6-4 Challenger first appeared on U This is an MTH 70-3016-1 Union Pacific 4-6-6-4 Challenger Steam Engine w/Proto-Sound 2.0, (Yellow Stripes) Cab No. 3980. In the midst of the Great Depression, Union Pacific designed and asked ALCO to build the best high-speed simple articulated engines to grace American rails.Union Pacific LionMaster TMCC 4-6-6-4 Challenger #3983 SKU: 6-28077. Union Pacific LionMaster TMCC 4-6-6-4 Challenger #3983. $ 799.95. Find A Dealer. Imagine the world’s largest and most famous steam locomotives running on your layout of O-31 radius track. A fantasy? Product Spotlight - HO Challenger. M.T.H. Electric Trains has begun shipping its 4-6-6-4 Challenger die-cast HO steam engine. A total of six paint schemes are being offered in standard DC 2- Rail and AC/DC 3-Rail configurations. Each model comes equipped with the most advanced sound and operating system ever installed in HO scale. The Union Pacific introduced the 4-6-6-4 in 1936 and ended up owning the largest and most famous fleet of Challengers. Designed as freight haulers, they were regularly used in high-speed passenger service. The line’s fleet operated well into the diesel era, with the last Challenger being dropped from the roster in 1962.Find many great new & used options and get the best deals for AHM Challenger -4-6-6-4 -5113-05- Rio Grande -Minty Box at the best online prices at eBay! Free shipping for many products!Oct 9, 2013 · sc e2 bi polar sc usra 0-6-0 rk fef northern rk hudson hiawatha sc nh l5 4-6-4 rk aero train rk usra y6b sc wm challenger rk ese sc c&nw e-4 sc gp-30 sc russian dacapod sc z-6 challenger rk wabash hudson sc orient express sc gp-9 sc gg1 sc class a rk disney engine in vt sc ese hudson sc e-8 rk usra mallot sc berkshire rk p-47 baldwin sc ... The name Challenger was given to steam locomotives with a 4-6-6-4 wheel arrangement. This means that they have four wheels in the leading "pilot" truck, which helps guide the locomotive into curves; two sets of six "driving" wheels, and finally, four "trailing" wheels, which support the rear of the engine and its massive firebox.Union Pacific LEGACY 4-6-6-4 Challenger #3985 (BLACK) Challengers for the first time in American Flyer S Gauge. With the advent of diminished locomotive production due to World War II demands and restrictions, many western railroads were hungry for top performing and even more powerful steamers.The class Z-8 Challengers had a starting tractive effort of 107,000 pounds and were the most powerful 4-6-6-4s ever built. During their careers, the class Z-8 Challengers sped freight as well as a passenger and troop trains along the NP main. All were retired by 1957. The N scale model’s plastic boiler features well-defined molded detail.Athearn N Challenger 4-6-6-4 For N scale fans of big articulated steam locomotives, what's more exciting than a 1:160-proportion Challenger 4-6-6-4? How about one equipped with realistic onboard sound. The Challenger is the first DCC-and-sound-equipped N scale steamer in Athearn's product line.Delivered Mar. 2017. The first Challengers were conceived in 1936 as fast freight engines to replace the Union Pacific's fleet of three-cylinder 4-12-2 locomotives. With an extra center cylinder for added power and a top speed of 45 mph, the 4-12-2s had been successful freight engines when built in 1926. But a decade later they were considered ...AMONG THE LATEST in Lionel’s LionMaster line of traditional-sized locomotives is an exceptionally sharp rendering of a Union Pacific-style 4-6-6-4 Challenger, painted and lettered for the Western Maryland Railroad. Although in real life that Appalachian coal hauler used a different style of 4-6-6-4 locomotive, Lionel’s model will probably ...Union Pacific Railroad No. 3985, also known as 'The Challenger', is a 4664-4 class 4-6-6-4 "Challenger" type articulated steam locomotive built by the American Locomotive Company (ALCO) in July 1943. It was previously owned and operated by the Union Pacific Railroad (UP) in excursion service as part of their heritage fleet, based in Cheyenne, WY, from April 1981 until being taken out of ...The name "Challenger" was given to steam locomotives with a 4-6-6-4 wheel arrangement. This means that they have four wheels in the leading pilot truck, which helps guide the locomotive into curves, two sets of six driving wheels, and finally four trailing wheels, which support the rear of the engine and its massive firebox. May 1, 2006 · AMONG THE LATEST in Lionel’s LionMaster line of traditional-sized locomotives is an exceptionally sharp rendering of a Union Pacific-style 4-6-6-4 Challenger, painted and lettered for the Western Maryland Railroad. Although in real life that Appalachian coal hauler used a different style of 4-6-6-4 locomotive, Lionel’s model will probably ... Find many great new & used options and get the best deals for AHM Challenger -4-6-6-4 -5113-05- Rio Grande -Minty Box at the best online prices at eBay! Free shipping for many products!Bowser - HO - Steam Loco Kits Union Pacific Challenger 4-6-6-4. History: The 4-6-6-4 class, original Challenger was designed by Otto Jabelmann of the Union Pacific and first built by Alco for UP. Approximately 230 Challengers were built nearly alike, differing only in their steam pressure, cylinders, and boilers.JLC Clinchfield TMCC 4-6-6-4 Challenger #673 (TMCC) Back by popular demand, the Joshua Lionel Cowen Series Challenger is sure to thrill and amaze you. Built with more detail than anything previously attempted in O-Gauge die-cast, this locomotive is the piece de resistance of any collection. AMONG THE LATEST in Lionel’s LionMaster line of traditional-sized locomotives is an exceptionally sharp rendering of a Union Pacific-style 4-6-6-4 Challenger, painted and lettered for the Western Maryland Railroad. Although in real life that Appalachian coal hauler used a different style of 4-6-6-4 locomotive, Lionel’s model will probably ...Reviewing my recently purchased AHM Rivarossi - ALCO Schenectady 4-6-6-4 "Challenger" road number 1506 with the Delaware & Hudson.The model is a AHM Rivaros...
Union Pacific LEGACY LionMaster Challenger 4-6-6-4 Steam Locomotive #3977 (Greyhound) $ 999.99. Find A Dealer. LionMaster Challengers: The power and excitement of these great locomotives comes with all the features of our scale LEGACY models but in a size runs on O31 curves!. Language_view
Athearn Genesis Rio Grande 4-6-6-4 Challenger with factory MRC sound pulling a freight through Minturn, CO on my Tennessee Pass line layout.Delivered Mar. 2017. The first Challengers were conceived in 1936 as fast freight engines to replace the Union Pacific's fleet of three-cylinder 4-12-2 locomotives. With an extra center cylinder for added power and a top speed of 45 mph, the 4-12-2s had been successful freight engines when built in 1926. But a decade later they were considered ...The new Trix 4-6-6-4 represents Union Pacific’s final group of Challengers built between 1942 and 1944. For its initial release, Trix’s HO model features an oil tender, and the locomotive is equipped with “wind wings” that aided the prototype in deflecting the exhaust smoke up and away from the cab.Delivered Mar. 2017. The first Challengers were conceived in 1936 as fast freight engines to replace the Union Pacific's fleet of three-cylinder 4-12-2 locomotives. With an extra center cylinder for added power and a top speed of 45 mph, the 4-12-2s had been successful freight engines when built in 1926. But a decade later they were considered ...Introducing Broadway Limited Imports' newest addition to our line of N Scale steam locomotives, the Union Pacific Late Challenger.Between 1936 and 1944, the American Locomotive Company (ALCO) constructed a total of 105 Challengers in five classes for the Find many great new & used options and get the best deals for Athearn Genesis HO Union Pacific Challenger 4-6-6-4 3982 Retail at the best online prices at eBay! Free shipping for many products!Locking your locomotive into a single operational state 4 Your locomotive’s Odyssey™ System speed control 5 Using your tender-mounted ElectroCoupler in the non-Command environment 6 Your locomotive’s RailSounds system—the basics 7 Experiencing the range of your locomotive’s RailSounds system 8 Notes on RailSounds 8Part of the April 2016 New Announcements are the CSA-1 and CSA-2 "Original" or "Light" Challengers. These were built in 1936 and 1937 for the Union Pacific Railroad and posses some key spotting features. Athearn Genesis Rio Grande 4-6-6-4 Challenger with factory MRC sound pulling a freight through Minturn, CO on my Tennessee Pass line layout. The name Challenger was given to steam locomotives with a 4-6-6-4 wheel arrangement. This means that they have four wheels in the leading "pilot" truck, which helps guide the locomotive into curves; two sets of six "driving" wheels, and finally, four "trailing" wheels, which support the rear of the engine and its massive firebox. In Whyte notation, a 4-6-6-4 is a railroad steam locomotive that has four leading wheels followed by six coupled driving wheels, a second set of six driving wheels and four trailing wheels. 4-6-6-4's are commonly known as Challengers. [1] A similar wheel arrangement exists for Garratt locomotives, but is referred to as 4-6-0+0-6-4. .