All the video I have seen shows the Big Boy running at maybe 30 mph max. Is there a break-in period going on now which, after that’s complete, UP will run the engine faster?
I would love to see it go 60-70. I thought seriously about going out west to watch these runs, but I’m glad I didn’t. I am hoping if I were to travel to UP territory for future trips, maybe I’d get to witness higher speeds.
If they don’t need to run it faster, they won’t. The faster it goes, the more stress it puts on parts and the sooner they fail. Why wear it out quickly, if they don’t have to. Nice and easy means they get to “enjoy” their well-spent money longer. This also gives more of us a chance to make the trip to see it with our own eyes.
They might, but not right now.
Keep in mind 4014 is still in the break-in and post-restoration “de-bugging” phase. As we’ve seen from the videos there’s some “blow-by” of escaping steam from the forward cylinders. Not catastrophic, but it will need to be dealt with for the max efficiency of the locomotive. There may be some other “quirks” that will have to be addressed, and remember, it’s been almost 60 years since a Big Boy has run in regular service. Some, if not a lot, of operating expertise of that particular class is going to have to be re-learned by doing.
It’ll probably be given the chance to open up eventually, but right now, no.
It’s the smart policy to follow.
LithoneaOper…,
The articulated steam locomotive in America has never been a truely high speed design. Some of the early “Mallet” locomotives were astoundingly low speed engines. As the articulated design developed into a “simple” locomotive higher speeds were achieved with the UP Challenger likely one of the best.
The use of the term “Mallet” as opposed to “simple” engine design refers to the Mallet usually being a compounded engine in which steam works in smaller cylinders and then is piped to work in larger cylinders. This extracts more work from the hot steam by using it twice. The “simple” engine uses the steam only once before exhausting it. UP3985 and UP4014 and UP844 are all “simple” engines.
“Articulated” locomotives mean that two sets of cylinders and drive wheels are coupled under one locomotive boiler and the engine is in effect hinged in the middle. This design has always been fraught with problems because the front engine acts different from the rear engine. Articulated locomotives were famous for the galloping front engine which often track differently. This inherently limited the speed of the engine.
It is interesting to note that AT&SF railroad entirely gave up articulated steam locmotives as unworkable and went with ridged frame engines like the huge ATSF 2-10-4 freight engines. The Union Pacific went exactly opposite from 4-12-2 ridged frame engines to articulated 4-6-6-4 and 4-8-8-4 classes of outstanding articulated engines.
It is truely remarkable that UP3895 has run the impressive speeds in passenger work as a 4-6-6-4 engine and shows the mastery of controlling the front engine. To house break the UP4014 to run at speed required them to “tame” that front engine - which is a full eight wheel drive.
This is the reason Ed Dickens spent so much time preparing the front locomotive to be absolutely perfe
Thanks, all.
UP 3985 has been run at 70 MPH with its 69-inch drivers. I had the good fortune to pace it for a period of time back in the 1990s when I was living in Sacramento and UP sent it west on the former Western Pacific to Oakland. It was doing all of 70 mph.
Here is UP 3985 in Nebraska:
https://m.youtube.com/watch?v=gNQEoUiS2A0
UP 844 has 80-inch drivers and according to reference books was designed for 100 mph. It has been paced at 75 mph:
https://m.youtube.com/watch?v=HRTYNxtbnjI
4014 has 68-inch drivers. Reference books indicate it was designed for 80 mph but I am not aware of instances where it ever ran at that speed. However, given the long distances from Cheyenne to most cities, I wouldn’t be surprised to eventually see 50 mph and maybe even 60 mph on occasion.
This video: https://www.youtube.com/watch?v=YpJlnPOK26E does show some pretty quick running. Look around 1:45.
I think in their prime Big Boys did regulary hit 60 mph or slightly more.
In the Spring 2019 Classic Trains there is an excellent article about Big Boys running on the Los Angeles & Salt Lake between Ogden and Milford UT for 9 months in 1943. They apparently performed so well, pulling 5,600-ton trains at 60-65 mph, that the UP was drawing up plans for a 4884-3 class 4025-4029 that would have been oil-fired and had 33,000 gallon tenders on a 4-10-2 wheelbase (with the single-axle truck on the rear helping to guide the tender on reverse moves).
The 4884-3 units were never built due to use of the two atomic bombs shortening the war.
Didn’t the UP themselves state that during the run from Cheyenne to SLC/Ogden and back that speed would vary between 30 and 60? I’m pretty sure I remember reading that in one of the information posts here on the Trains website.
One thing I just noticed - on the 4014 the Main Rod from the piston is connected to the 3rd driver set on both engines. On the 844 the Main Rod is connected to the 2nd set of drivers.
I suspect there is a engineering reason for this - but I have no idea what it would be.
This is common in modern locomotive design: it’s a basic tradeoff between minimizing main-rod mass (to minimize augment at high speed) vs. minimizing rod angularity (for a variety of reasons including keeping off-axis effects of high piston thrust minimized)
One of the reasons for working on advanced locomotives like the AMC Berkshires and the N&W A class is that you can have a rod with relatively low angularity acting on the third driver pair that goes to a crosshead and relatively short piston rod right up close to the cylinders. An engine with a leading Adams-bogie pin-guided engine truck requires accommodation for the space occupied by the back wheel of the truck, so the wheel and truck clears the lead driver at all times. In the age before lightweight rod design, the N&W very famously designed a 4-8-2 with drive on the third pair – this resulted in excessively long and heavy mains, and I believe those engines were considered dogs no matter where they went (which bridge was it that you were supposed to hear the sledge noise BANG, BANG, BANG all the way across with loose bolts and parts falling off it?)
Now, when you progress to Mallet-chassis articulateds, it helps to have all the mains be the same dimensions. The N&W A, for example, and the Alleghenies do this natively: the two engines’ running gear can be identical. This is also true for the PRR S1 duplex, but the follow-on T1, which has a four-wheel truck, needs a greatly extended piston rod and longer crosshead guide structure to be able to use the same length main.
The 4014 rear engine doesn’t have a leading truck, so a rod short enough to bear on the 2nd driver pair would be impossibly short. It might have been possible to have driv
By your horsepower figures, you mean indicated (cylinder) not drawbar horsepower, I presume?
Your run-of-the-mill Northern didn’t produce 6000 HP – that is more in the province of the few super Northerns such as the Niagara, what AT&SF had and maybe the N&W J-class.
Producing 7500 HP was at the lofty HP heights of maybe only a couple steam locomotives, the Pennsy Q2 (divided drive, rigid frame) and the C&O H8 Allegheny (articulated)? Maybe the N&W A-class being in the mid 6000 HP range?
I am remembering that a Big Boy was rated at about 6000 HP at its top end?
It was in that ballpark, but I think it was a bit closer to 6,500 hp. 6,400 sounds about right, if my recollections of old issues of Trains is accurate.
Edit: The chart on page 85 of the 2004 special issue Steam Glory has it down as 6,300 horsepower at 41 mph for maximum horsepower.
Speaking of design top speed or fastest operating speed of engines with smaller drivers. The UP CSA-2 Class “Early Challenger” (69" diameter drivers) could hit 70mph when pulling passenger trains. Another one was SP SP-1/2/3 4-10-2, maximum speed was 60mph. (63.5" diameter drivers)
This page has a table of comparative statistics of articulated locomotives including a partial list of horsepower figures:
https://www.steamlocomotive.com/locobase.php?country=USA&wheel=4-8-8-4#
The average speed for the Rawlins, WY to Wamsutter, WY leg of the trip worked out to be 62 mph. However, I was following the train during this stretch, catching it at the Wyoming road 789 overpass near Creston, and it was not running anywhere near 60 mph. Maybe closer to 40. I’d be surprised if they exceeded 50 mph anywhere on the trip.
Do you mean the planned average speed was 62? Because then you suggest that may not have been possible.
I think he was referring to a segment listed in Jim Wrinn’s 04/29/19 blog that listed a segment of the schedule between those two points as 78 miles in 75 minutes. I think that was a typo because Google Maps shows them being 40 miles apart and the railroad is close by I-80. 40 miles in 75 minutes is 32 mph.
I don’t think they would run Big Boy at 60 mph until it is well broken in. He is certainly capable of that speed with 68-inch drivers just as 3985 or NKP 765 are capable of all that and more with drivers just one inch larger.
If anyone ever really questioned what 3985 was capable of speed wise, I personally witnessed it at high speed.
When 3985 ran from Cheyenne to Pocatello in 1982, at some point after Laramie the speed recorder broke. My wife, friend, and his wife had dinner with the crew that night in Pocatello and I asked Steve Lee, who at that time was just an ordinary crew member how fast they were going at one point. He laughed and mention the recorder was broken and they were not paying particular attention to the speed until one of the crew took out a watch and timed the mile. He said it was 84.5 mph. I had no doubt he was correct. We had seen the train coming toward us and turned around to catch up. Turns out my rental car was only capable og 80 mph. 3985 was pulling away. We were blown away. So when someone suggested a Big Boy could do 80, I would agree based on seeing 3985 out run our car. There is no reason to try and find out and abuse it today, however.
I expect they will try for something for fun at some point, like an all time tonnage record.
I also witnessed and recorded an awesome interview with Ed Dickens in Rawlings, and he intends to break in the engine very carefully since there were more new parts on that thing than Carter has little pills. They also had to get some idea on oil consumption to plan for future trips. It had a mere 70 miles on it before they left Cheyenne. Only UP could have pulled this off. Congrats to Ed and group and hope to see Big Boy do what it did best- conquer the grades.
Yes, I should have said the planned average speed, not the actual average speed.
Scott Griggs
Louisville, KY