The Pennsylvania Railroad's Worst Duplex Steam Locomotive | PRR Q1 | History in the Dark

Added: 2026-05-22

[00:00:00]The Pennsylvania Railroad Class Q1 number 6130 was a single example of an experimental duplex steam locomotive designed for dual service operation. She was a perplexing design and had streamlining at least early on in her career, but unlike a lot of duplexes which tend to get a bad rap and weren't quite as bad as sometimes stated, the Q1 was a complete disaster.

[00:00:36]The Class Q1 was just another example of the Pennsy attempting to create a fleet of duplex drive steam locomotives. They had already had their showpiece with the S1 and they were almost finished with the T1s, but those were both passenger designs exclusively. The Q1 was different in that they meant her for dual service, for both passenger and freight, and she had a bit of a different design ethos as a direct result and a lot of terrible decisions, actually. Well, okay, scratch that. Not a lot of terrible decisions.

[00:01:12]But there was one major terrible decision that really really ruined her.

[00:01:21]She was constructed by Pennsylvania Railroad's own Altoona Shops in 1942 and she had a really weird wheel arrangement.

[00:01:30]She was a 4-6-4-4.

[00:01:33]That's four leaders followed by six drivers followed by a different set of four drivers and then four trailers.

[00:01:43]You usually don't see that. In fact, I'm pretty sure outside of duplex designs having two sets of drivers with different amounts is nearly unheard of.

[00:01:55]This particular one is exclusive to the Q1. She's the only one that ever had this arrangement to anyone's knowledge.

[00:02:02]And the reason is that she's a duplex.

[00:02:04]See, on simple articulates and and mallets by extension, they don't usually have different amounts of drivers. They have two different sets of drivers, yeah, but the intent behind the articulates is meant to kind of like let them negotiate curves cuz they're articulated, but also give them more tractive effort and power.

[00:02:23]Duplex design ethos is a quite in line with that. Tractive effort and power is relevant, but the real intention is weight. Whenever you divide the drive like this into a duplex setup without making it articulated, it's meant to reduce the weight of things like the running gear, as well as provide more speed. In this particular setup, the intention is to effectively create a 4-10-4 wheel arrangement, but without having the overloaded nature of running gear required to push five coupled axles for 10 wheels forward. If you divide them, then you could have two smaller sets of running gear. The idea is that it's less maintenance, it's less weight, less wear on the rails, less hammer blow, and yes, that is all true when it comes to the duplex designs. And that's why she has this weird wheel arrangement. They wanted 10 drivers. The Pennsylvania Board of Directors approved her construction on October 9th, 1940, and put forward $595,000 for her. That's equivalent to about 13 and 1/2 million today. So, yeah, she was not cheap. Her early streamline shrouding was again designed by Raymond Loewy, who also handled the S1. Though, in this case, he went for a much more minimalist setup. She's not quite as elegant as the S1 was, but I suspect this is related to the fact she was intended for dual service. She was also supposed to pull freight trains. And she does look stylish in her own way. When it came to functionality, well, on paper, her performance was very good.

[00:04:03]She could hit at least 70 mph, had a power output of 6,000 horsepower, and a total tractive effort, if you include her booster unit, because she did have one of those, was 93,043 lbs of force. Very nice. She was also smaller than the S1. So, in theory, she would have more route availability as a direct result, because the S1 was too big for a lot of areas.

[00:04:30]And the Q1 would be the very last dual service locomotive that was designed by the Pennsy.

[00:04:35]However, despite being at dual service, she, um, well, there's no record they ever put her on a passenger train, to be honest.

[00:04:49]Part of the reason is that she was completed about the same time the T1s were in service, and they were exclusively for passenger express service. Perhaps they thought it better to test out the dual service on freight.

[00:05:00]But, the other, far more major reason is that, again, her impressive performance is all on paper. And when she was functional, yeah, she could do all that, but she sucked hard. Unlike the other Pennsy duplexes, which had some issues and teething problems, the Q1's design was doomed from the start. There's a reason she never got any sisters. And as I alluded to earlier, the cause of pretty much all her problems was that.

[00:05:29]That. Right there.

[00:05:33]I don't know who decided that they were going to reverse the rear cylinders for her.

[00:05:45]But, I've seen this particular design choice on only a handful of steam locomotives and nearly every time with like one exception this is asking for trouble.

[00:05:59]It's not so much that having to reverse the cylinder causes problems when it comes to synergy with the forward-facing ones. That wasn't her issue. The issue is the location itself.

[00:06:11]In terms of functionality, that cylinder is fine. She had Walschaerts valve gear.

[00:06:16]That's all she had. Very standard, very normal, nothing weird about that and perfectly reliable. But because it was put there it caused a whole heap of trouble. In terms of the cylinder itself well, it's right next to the firebox.

[00:06:33]The firebox um happens to be where the fire is if you weren't already aware of that and where the coal goes to feed the fire. As a result, the heat and soot that is naturally occurring in and around the firebox caused significant wear on that cylinder, much more so than normal. And it wasn't just the firebox was hurting the cylinders, it was the cylinder had hurt the firebox. By putting them there, that restricted the size that the firebox was allowed to be and as a result she had one that was a bit too small for her.

[00:07:11]She didn't steam particularly well.

[00:07:13]Whereas a lot of the other duplexes were free steamers, the Q1 often struggled causing the crew to have to work harder to keep her going. Another problem this particular design choice caused was that the steam pipes had to be longer to even reach the cylinders all the way back there. And that meant a fair degree of power loss just because of having to travel further. And the only problem that had nothing to do with this but was still a problem was that because she was dual service was decided to give her drivers the that were 77 in in diameter.

[00:07:48]The problem with that is that that's a really bad size for freight trains.

[00:07:53]So, she also struggled there, too. Crews didn't like her. The railway didn't like her because again, unlike the S1, who saw pretty extensive use despite her limited route availability, the Q1 barely got run at all. Between the years of 1942 to 1949, when she'd be pulled from service, she only ran about 165,000 service miles, which is pretty pathetic, especially when you compare her to the S1, who had an average of over 10,000 miles a month, leading to 120,000 miles on average a year for several years.

[00:08:31]The fact that the Q1 only ever hit 165,000 in her entire life kind of shows how bad she really was.

[00:08:39]Most of the time she was in the shops because of her cylinders or because of something else that went wrong. She was not good at all.

[00:08:47]And she'd finally be withdrawn in 1949 and not slated for preservation because because no.

[00:08:56]She was scrapped in 1952, but it is worth mentioning that despite her problems, uh despite everything, she did teach the Penzie quite a bit.

[00:09:07]They learned from her shortcomings, and she would wind up leading to effectively daughters, the Q2.

[00:09:15]This particular group of locomotives were also duplexes, but instead of a 4-6-4-4 wheel arrangement, they had a 4-4-6-4 wheel arrangement. They swapped the drivers, and they put both cylinders facing forwards.

[00:09:30]Thank you.

[00:09:31]Thank you for that. The class consisted of a single prototype and 25 production models. Yes, this one actually entered production. And they still did not serve for very long, but not because they were bad. They were built exclusively for freight, not dual service, and handled it fairly well.

[00:09:49]The problem was dieselization.

[00:09:51]At the end of the day, all steam engines were being replaced by diesels, and that included the Q2s. And sadly, not a single one of them was preserved either.

[00:10:01]The final one was withdrawn in 1951.

[00:10:05]Till next time. This is darkness individual and farewell.