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| Steaming "square"
https://rypn.org/forums/viewtopic.php?f=1&t=1045 |
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| Author: | O. Anderson [ Thu Feb 17, 2000 12:55 am ] |
| Post subject: | Steaming "square" |
<br>Recently I have heard the phrase used "we got that engine to run square" when talking about drive system rebuilding. If I understand correctly, does this mean that the lengths of time the cylinders move back and forth are equal in duration and precisely separated by half a stroke? I know that the driving rods are attached to the wheels at a 1/4 separation on opposite sides, so I assume when an engine is "out of square" this means that the offset is loose or mislocated. Do the frame construction and drive wheel journals add to out of square problems?<br>And just out of curiosity, did the 3-cylinder steam engines "run hex?"<br>Thanks for any help you all may offer.<br>Olin.<br> oanderso@uiuc.edu |
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| Author: | HKA [ Thu Feb 17, 2000 4:38 am ] |
| Post subject: | Re: Steaming "square" |
An engine being "square" refers to the accuracy of its valve timing. A “square” engine will run down the track making four equal exhausts for every turn on the drivers. Equal in volume, equal in spacing, equal in duration. When the four exhausts are not equal, the engine is referred to as being “out of square”, or “lame”. In practice, it is very difficult to make an engine perfectly square, there is almost always a little variation from one exhaust to the next, that sets up a pattern that repeats every revolution. Some engines do run perfectly square, but not many. The PRR 1223 at Strasburg was square, and I saw a video of narrow gage 2-8-4’s in Africa with one runby in particular that was striking for being perfectly square.<p>When an engine’s axles are perpendicular to the engine’s frame it is referred to as being “in tram”. If that is not the case, it is “out of tram”. An engine running out of tram will wear out its flanges in very short order.<p>When an engine’s crankpins are exactly 90 degrees apart from one side to the other, the wheels are said to be “in quarter”. If they aren’t, it’s “out of quarter”. If all the wheels are out of quarter the same amount in the same direction, there isn’t a problem. If one or more wheels are out of quarter different amounts, the engine will bind up as it runs, heating and wearing the crankpins, and brasses.<br><br> |
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| Author: | Alexander D. Mitchell IV [ Thu Feb 17, 2000 6:25 am ] |
| Post subject: | The opposite of steaming "square" |
Somewhere in my extensive LP collection, I have a recording of a British 0-4-0ST or 0-6-0ST, WW2 vintage or thereabouts, lugging and struggling with coal out of a colliery on a heavy grade, running *so* badly off time that the four beats from the stack were perfectly square, yet there was enough gap between beats four and one to stick a *FIFTH* exhaust!!! Imagine: "Choo-CHOO-choo-choo-(pause), choo-CHOO-choo-choo-(pause)..... This recording mystifies me to this day. How in tarnation could a steam locomotive be SO off-beat as to limp *this* badly? Any answers? Do I have to transfer this sound clip to MP3 for disbelievers?<br>To answer about three-cylinder steamers: The description I always give to describe the sound is "a steam locomotive doing a jig instead of a reel".<br> LNER4472@gateway.net |
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| Author: | Dave [ Thu Feb 17, 2000 6:21 pm ] |
| Post subject: | Re: The opposite of steaming "square" |
I think I rode behind this one at Lakeside and Haverthwaite last summer. <p>Just now setting valves on GOAT and found both valves over 1" too far forward in the chests. Since we didn't change the boxes, shoes and wedges since they weren't worn, she must have been this far out in her last years at Georgia Power. We will need to actually cut some length out of the valve rod extensions to get her back into the realm of adjustability. <p>3 Cylinder locomotives are easier assuming they are Shays. You don't have to push the whole engine back and forth, and dead centers for each cylinder are easily determined from the other two. You just set the lead equal at both ends and she'll be right, mate. <p>Dave<br> lathro19@idt.net |
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| Author: | Paul Hubbard [ Fri Feb 18, 2000 8:11 am ] |
| Post subject: | Re: The opposite of steaming "square" |
The first run of Southern Pacific #2472 on the way to Sacremento's 1991 Railfair clearly captured her out of square condition. Pentrex's video of this event has great audio. The 2472 sounded like she was beating herself to death! I believe Mr. McCormack helped the GGRM set the valves. <br> hubbard5004@msn.com |
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| Author: | Robert [ Fri Feb 18, 2000 11:04 am ] |
| Post subject: | Re: The opposite of steaming "square" |
I beleive the problem was that the shoes and wedges were so far out of adjustment. Bill Stetler of the daylight crew set them up correctly while the engine was on display, then took it out for a test spin. <br> |
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