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Thread: The T1 is starting to shape up

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    Default The T1 is starting to shape up

    I had no idea they were this far along with it: https://www.trains.com/trn/news-revi...am-locomotive/



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    That is so cool! I didn't even know this was happening!

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    Quote Originally Posted by CSXRobert View Post
    That is so cool! I didn't even know this was happening!
    Yeah it's pretty ambitious (maybe even a bit crazy) that anyone would even attempt to do a new build on such a big and complex locomotive. Supposedly it's going to be modernized too with the ability to MU with modern diesels and other modern features. They're also going the unconventional route with the valve gear and using a rotary cam instead of a more traditional setup, which is something I didn't even realize existed until I read up on the T1 trust.

    Here's a 3D rendering of the valve gear they posted on YouTube:


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    Quote Originally Posted by drosera88 View Post
    Yeah it's pretty ambitious (maybe even a bit crazy) that anyone would even attempt to do a new build on such a big and complex locomotive. Supposedly it's going to be modernized too with the ability to MU with modern diesels and other modern features. They're also going the unconventional route with the valve gear and using a rotary cam instead of a more traditional setup, which is something I didn't even realize existed until I read up on the T1 trust.
    Unconventional yes, but apparently prototypical. I too had never heard of that kind of valve gear before, so I dug into it. Apparently there was some experimenting on the T1 valve gears as they were a weak spot. You can read a discussion here and there's also a thread about rotary cam valve gears on the Trains forum.
    According to Revivaler (the first link), T1 #5547 ended up with a traditional Walschaerts valve gear, making it a class T1A. The author hints at the possibility that #5547 became more reliable and easier to maintain because of it, but there's no apparent evidence to back up that claim. Stands to reason, though.

    Anyway, interesting stuff
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    The T1 ended up with the Franklin Type A poppet valve. The PRR did some experiments with a K4s and the Franklin Type B poppet which turned out to be a little more reliable. The Type B is what was referred to in that article as the rotary valve. It could handle the higher speed that the T1 reached better than the Type A. At those speeds the Type A often reached or exceeded it's stress design specs and broke. Unfortunately, that was after the first two T1's had been built and the rest ordered. If the Type B had been available a year or so earlier, then it's probable that the T1's would have had it and a lot of their reliability issues wouldn't have ever happened. As it was the EMD E7 and E8 came along and made steam obsolete on passenger trains anyway which means the T1's never lasted long enough to be candidates for rebuilding and getting upgrades like the Type B poppet.
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    The ability to MU is certainly interesting, wonder if they'll try and stuff PTC in the thing. UP did it, provided it was effectively a computer with a ziptie attached to a dump valve...
    :gp38::chop::beam::box:

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    Quote Originally Posted by reinhardtjh View Post
    The T1 ended up with the Franklin Type A poppet valve. The PRR did some experiments with a K4s and the Franklin Type B poppet which turned out to be a little more reliable.
    I had no idea that was a thing either.


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    Okay, maybe we should have a different thread about valve gears. I've searched a bit more for Franklin type B gears in an attempt to understand how they work. I haven't figured it out yet, but I came across a couple of British projects by the same team that built the A1 Tornado.
    They are currently scratch building a class P2 locomotive, which (as I read it) will get Franklin type B valve gears. There's a design study posted, which is quite interesting to read, and they even have more projects in the pipeline.

    Wow

    Another thing I noted is that the British class 8 no. 71000 Duke of Cloucester in fact has poppet valve gears, but type Capriotti ... whatever the difference may be. I need to look into that too. Dang, curiosity is getting the better of me now ...
    The thing is - I've actually seen #71000 some years ago on the East Lancashire Railway north of Manchester UK. It was late in the evening and it was dark, so I didn't walk around gawking at technical details, but if I had been aware of the poppet valve gear, I would have been all over it.
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    Quote Originally Posted by SteamPower4ever View Post
    I've searched a bit more for Franklin type B gears in an attempt to understand how they work. I haven't figured it out yet
    I think it works by substituting the reciprocating motion of a valve rod for the rotary motion of a camshaft to operate the valves that controls the flow of steam into and out of the piston cylinder. It looks like there's a gearbox on one end (where the eccentric rod would be coupled to in a traditional valve gear) that is aligned with the axle of one of the drivers to turn the cam shaft. It looks like the other end is where the shaft interfaces with the valves to open and close them. Not 100% sure on all this.


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