What is the largest Locomotive that Can be used on a 18 in radius?
It depends on a lot of factors. The largest I have run personally is the Bachmann 2-8-4 and it derails on occasion. I'd just get a 2-8-0 or something in that size range ans use it.
Stick to 4 axle diesels or steam lcomotives with a short wheel base such as an 0-4-0, 0-6-0, 2-6-0 or 2-6-2. In my personal experience a 2-8-4 requires a 22" minimum radius, on 18" radius it derails quite often. I suggest to play it safe to avoid problems down the line. Tell us what you have in mind and we can likely advise what your minimum radius should be.
it is not so much a question of how large a locomotive can negotiate an 18r curve, it is a question of can this locomotive negotiate the curve while pulling a train without derailing whatever is coupled to it. locomotives and cars work best on 18r if they are shorter than about 50 scale feet (7 inches)
Rie-
The modern model railroad industry has found ways to get very large locomotives around 18" curves. However, that doesn't mean you should run right out and buy one to haul your trains. Putting oversize locomotives on tight curves looks worse than ridiculous and often leads to serious operating problems, including with the rolling stock they haul.
Nevertheless, I can tell you about a fairly long list of big steam and other locos which can negotiate 18" curves: Broadway Limited sells Hudson, Decapods, Pacifics, Mountains, Northerns and Mikes which can do it. Mike's Train House offers Northerns, Challengers, Big Boys (which are longer than 18 inches!!), Triplexes (2-8-8-8-2) in steam and GE ES44ACs, GE Dash9-44CWs, EMD SD70ACes, Pennsy GG-1s and Milwaukee Bi-Polars.
You'll notice that our hosts here, Bachmann, don't sell rail giants to run on toy train curves. I like to think that's because they realize just how preposterous this is and they don't want to set their customers up for frustration when they get their shiny Big Boy, only to find that they're lucky to get three laps around their 4x8 layout without a derailment of the loco or its consist. Or both. And, heaven help us if you try to back one of those beasts with the train leading the way (for a few inches). -- D
Yeah, that wouldn't work well would it! I had no idea that MTH was making such huge locomotives that could do it, though as you said those cars are gonna hop the track rather quick. THe 2-8-4 I mentioned looks silly doing it and derails too often for my taste. That said, Bachmann makes or has made locomotives that look nice on the curves (or as nice as a loco can look on 18). the russian 2-10-0, the Chinese (not the new USRA which I donno) 2-8-2, the 4-4-0's, the 4-6-0, the 2-6-0, the Baldwin 2-8-0, and their geared locomotives will all do it.
Way too many variables to recommend definitive motive power on 18-inch radius trackage.
-Diesel or Steam?
-If steam size of tender; switcher, short or long haul?
-Era modeling or theme?
-Are you consisting (MU)?
-Maximum, or desired, number of rolling stock pulling (tractive effort)?
-Flat or mountain pike (grade percentage)?
Once you figure out your needs then you can choose the appropriate motive power.
I completely agree that a DD40AX or a H4 2-6-6-2 might work on a 22-inch radius curve, but it will look out of place. A consist of GP-38s or 40s might serve you better. If steam consider a 2-6-0, a USRA 0-6-0 or a Climax or Shay- -if your budget permits.
For switching duties consider a 110- 70- or 44-ton diesels or a 0-6-0 or 0-4-0(T) steam.
For short overland hops how about an RS-11 or RS-3, if appropriate for your concept.
And do not rule out the venerable F-series diesels, with accompanying B-units.
Hope this helps.
one exception to the general rule of not using 6 axle diesels on 18r curves would be the alco rsd5. this locomotive is basically an rs3 with 6 wheel trucks. I have 4 and they work well on my 18r curves.
Even if engine does make it though OK, with a 10, 15, 45 car train it's likely to have so much drag engine will either spin wheels in one place, or at speed whole train could pull strongly toward inside and derail or have a string drop down to floor or into the scenery. Small engines. Short trains. Slow speeds OK. A 2-6-6 2 T or S4 switcher, interurban, OK. NYC Hudson forget it ! It's simple logic. track physics are no different for the model than the 1:1 scale.. Related : If you have track ascending on a curve, what measured out to be a 2.5 % grade will make train behave as if it's a 3.5 to 4 % grade also due to drag from the curve and engine, again, will slip in place (until the day when we have operating sand domes !).
I guess a couple of other exceptions to whatever the general rule is, is the 2 SD45s and 1 SD9 that we run with no problems on 18" radius curves as well as through Snap Switches, I might add. The look of 6 axle diesels on 18" radius curves may not be for everyone though, especially those in the crowd that are railroad modelers, not model railroaders.
And I will further add, that in working on an old Athearn SDP40, which has 6 axles, for a friend of mine last weekend, I had it running around some EZ track I have on 18" radius curves, no problems. A further aside, not related to the OP's question was how to get the brass wheel sets on it cleaned as this thing is more than 30 years old. For anyone interested, instead of spraying WD40 on a paper towel which is what I have always read about, and running the wheels on the paper towel, I used PB Blaster instead and it made the wheels shine and clean like new.
We must remember there is a great amount of variability in these scale models. Even though some of us have experienced success running a particular model on 18 inch radius curves, it is many times the case that some will not be able to operate reliably on 18" radius curves.
For instance jbrock27, I have 3 Bachmann SD45s and only 1 of them runs on 18" radius reliably without frequent issues. Further all of my Athearn SD45s have issues on 18" radius but are fine on 22" radius track.
Irbrickseco, I have 3 Russian decapods, 1 Chineese 2-8-2, and several consolidations and out of the whole lot of them only 1 2-10-0 & 1 2-8-0 run reliably on 18" radius the rest run perfectly fine with no issues on 22" radius.
Doneldon, I just personally checked the operators manuals for the following BLI locomotives:
NYC Dreyfuss Hudson, 2-10-0, 4-6-2 (heavy), 4-8-4 J & Northern
And not one manual lists a minimum radius of 18", they all state 22" minimum radius and in my experience that is pretty accurate.
I also have MTH ES44ACs, SD70ACEs, a GG-1, a Northern, a bigboy and a friend has the Erie Triplex and the paperwork included states 22" suggested minimum radius. I recently attempted to run the NS heritage units on 18" radius to no avail.
Although it is very possible you were able to run the locomotives you listed sucessfully on 18" radius, I think it is a poor idea to make a blanket statement like you made just because of the variability on the models. It is better to list off just what will run on 18" radius safely 100% even with the variability instead of hoping you get lucly and get one that will make 18" radius without derailing or excessive binding.
Of course I am sure most of you were aware of the variability in the manufacturing process but I thought it was important to point this out before someone goes out and purchases a large wheelbase locomotive and is disapointed when it derails on.18" radius even though someone here said it would be fine.
True enough ACY. The common denominator for me is I have checked the gauges on all the wheels for our locos. In the event you may have overlooked this, have you checked yours? Also, free play of the trucks is important.
I would also agree/like to point out that the longer the wheel base of the loco, the more logical it will be that it does not run well on 18" R curves. If you ask me, the overall length and wheelbase of the loco is more important a factor than simply the number of axles.
Quote from: jbrock27 on October 17, 2014, 02:12:28 PM
True enough ACY. The common denominator for me is I have checked the gauges on all the wheels for our locos. In the event you may have overlooked this, have you checked yours? Also, free play of the trucks is important.
I would also agree/like to point out that the longer the wheel base of the loco, the more logical it will be that it does not run well on 18" R curves. If you ask me, the overall length and wheelbase of the loco is more important a factor than simply the number of axles.
One of the first things I do when I buy a new locomotive or piece of rolling stock is check to make sure everything is in line with the NMRA standards. None of my locomotives had wheels out of guage. Also another factor is if there are any blind drivers or not.
A while back, I started building the supply of Tichy ore cars I had been hoarding over the years; since they were Goulds... About twenty four cars later, I figured it was time to give 'em a shot on the rails. What to use for locomotives...! Well, I have five BACHMANN (See Dave? All is not lost here...) 2-6-0 Moguls. I set everything up on track and tried them out. Not only did the cars do well (the Kadee trucks helped lotsly, I am sure), but the locomotives looked REAL good, and operated very well on rather tight radii (I have policy of 24" minimum on my layout). All of this being said, I heartily recommend using smaller rigid-base (steam). They will look like a million dollars running on point or in tandem; on head of a local pedlar, or, as I have, on a mine or some industrial short line. The guys on this board have a lot of good info for you guys new to the hobby. Good luck!
Rich C.
Rich........
I like those Tichy ore cars too. I have one set of 12 completed and looking to do another string of 12 soon. I opted to use the Tichy trucks, and along with the added weight of the ore load, they seem to track pretty well. I usually assign a Shay or Climax to pull them. All is fine on the 18 inch sections.
On my layout, I knew 18 was going to have to be the ruling radius, so my motive power is limited as well. Common road engine for my layout is the Spectrum 4-6-0 with small drivers.
If you haven't got room for large radius curves, then accept the fact you can't run monstrous locomotives. You'll be much less frustrated in the long run.
Sid
(http://members.shaw.ca/wbearart1/Models/tichy02.jpg)
(http://members.shaw.ca/wbearart1/Models/tichy01.jpg)
(http://members.shaw.ca/wbearart1/Models/tichy03.jpg)
Quote from: ACY on October 17, 2014, 01:02:12 PM
Doneldon, I just personally checked the operators manuals for the following BLI locomotives:
NYC Dreyfuss Hudson, 2-10-0, 4-6-2 (heavy), 4-8-4 J & Northern
And not one manual lists a minimum radius of 18", they all state 22" minimum radius and in my experience that is pretty accurate.
I also have MTH ES44ACs, SD70ACEs, a GG-1, a Northern, a bigboy and a friend has the Erie Triplex and the paperwork included states 22" suggested minimum radius. I recently attempted to run the NS heritage units on 18" radius to no avail.
Although it is very possible you were able to run the locomotives you listed sucessfully on 18" radius, I think it is a poor idea to make a blanket statement like you made just because of the variability on the models. It is better to list off just what will run on 18" radius safely 100% even with the variability instead of hoping you get lucly and get one that will make 18" radius without derailing or excessive binding.
ACY-
I don't routinely run the locos I listed as able to run on 18" radius curves; I don't even own most of them. I took my information
from the BLI and MTH catalog pages about three minutes before I posted the information. I have to admit that I am more than a little
disappointed that people on this board would think I'm talking through my hat on this.
-- D
Great pics Sid!
-before someone goes out and purchases a large wheelbase locomotive and is disapointed when it derails on.18" radius even though someone here said it would be fine.
ACY, please let me point out that the converse can be true; that just bc you did not have success with a particular locomotive, does not mean it is a given that someone else might not either.
Let me ask you a question about your SD45s; are you still employing the long metal spring clip that traverses both trucks?
jbrock27, I have not modified them at all asise from installing a sound decoder in one unit since my layout has a minimum radius of 24" and my club has around 40" minimum radius on the mainlines.
Don, from the sounds of it there must be a misprint or error in the documentation. Not a week ago I tested my Broadway Limited Dreyfuss Hudson on 18" radius with it derailing incessantly and then ran it flawlessly on 22" radius. Even if the locomotive cold make 18" radius, there is no way the passenger cars would make anything less than 22" radius, infact my cars require 24" due to the underbody detail parts.
ACY, I am not sure whether your answer means the Athearn SD45s still have the metal spring clip I am asking about or never had them, can you clarify please?
With regard to your B'man SD45s, I can't help you there, but know that one of my good friends can run B'man SD45s on 18"R curves w/no problems, so I don't know why you have problems running them. I gotta believe he and I are not the only 2 out there who can run 6 axle locos on 18"R curves.
ACY, Are your curves laid correctly? Not that I don't believe you but I too used to have an SD45 from Bachmann and it handled 18 fine. Likewise my Chinese SY (and the one I had before) My Russian 2-10-0 (and the TWO i used to have) my two 2-8-0's (and the One i used to have) all ran flawlessly on 18.
I have 3 SD45's, 3 SD40-2's, 1 SD70 ACE all which would handle my 18r, but within reason.
Some rolling stock would not make it behind the SD's, too much swing. Had to alternate 50 footers and 40 footers in some areas.
Now my min radius is 26.
Quote from: Irbricksceo on October 18, 2014, 03:35:04 PM
ACY, Are your curves laid correctly? Not that I don't believe you but I too used to have an SD45 from Bachmann and it handled 18 fine. Likewise my Chinese SY (and the one I had before) My Russian 2-10-0 (and the TWO i used to have) my two 2-8-0's (and the One i used to have) all ran flawlessly on 18.
My layout did not have 18" radius, however I had several Bachmann train sets that came with 18" radius of EZ track, so I used those to set up a temporary layout consisting solely of 18" radius. A friend of mine owns a hobby shop with a large iinventory of model railroad items. At one point he had 10 Baxhmann consolidations in stock, I test ran all 10 briefly and found 7 of them could negotiate 18" radius and 3 could not but ran perfect on 22" radius. I had a top guy from Lionel who happened to be present that day (he is in charge of all factory repairs and service for Lionel), he lived in the same city as me at that time before Lionel moved the facility to North Carolina. Anyways, he looked at all 10 locomotives and could not find anything wrong with any of them and said the reason some likely could not negotiate tighter radius curves while others could is because each part is given a certain tolerance it has to be within but even a small difference of a sixteenth of an inch can impact its ability to run on 18" radius. Although it was a small sample size, I found 70% could make 18" radius while 30% could not, so they made 10,000 units hypothetically, 3,000 of those would be unable to run on 18" radius.
Quote from: jbrock27 on October 18, 2014, 07:33:23 AM
ACY, I am not sure whether your answer means the Athearn SD45s still have the metal spring clip I am asking about or never had them, can you clarify please?
With regard to your B'man SD45s, I can't help you there, but know that one of my good friends can run B'man SD45s on 18"R curves w/no problems, so I don't know why you have problems running them. I gotta believe he and I are not the only 2 out there who can run 6 axle locos on 18"R curves.
I will have to dig them out sometime to check, I don't recall off the top of my head sorry.
As far as the issues go, I would venture to guess that somewhere between 1-3 out of every 10 units have trouble with 18" radius. So it all comes down to luck somewhat since even though 90% may run fine on 18" radius, someone may purchase 50 units and have no issues while someone else could buy 3 or 4 and have issues with them all. That probably explains why many have not had amy issues and sometimes it is not until there is a large sample that it can be seen that 10-30% of a certain locomotive does not handle 18" radius curves.
[/quote]
I found 70% could make 18" radius while 30% could not, so they made 10,000 units hypothetically, 3,000 of those would be unable to run on 18" radius.
[/quote]
So your saying that the 7 I purchased that all negotiate 18r the next 3 will not?
It's hard to swallow your evaluation as I believe tolerances may have a small, very small part in the equation but quality assembling is much larger. Mass production tends to have more mistakes than tolerance. I have had to loosen, tighten, or adjust to make things tolerable.
ACY, you bring up a good point in that there could be a small section of them with lower tolerances, manufacturing works that way. That said, the 2-8-0 surprised me because it used to ship in sets with 18 inch radius curves (I know because I had one)
Quote from: Jerrys HO on October 18, 2014, 10:37:10 PM
So your saying that the 7 I purchased that all negotiate 18r the next 3 will not?
Jerry-
You're falling for the gamblers' fallacy. The chance that your next locomotive will be able to run on 18" radius track remains 70% regardless of how many locomotives you already have which do or don't negotiate 18 inches. It's the same with coin tossing. The chance of getting a head or tail is 50% no matter whether you have flipped 25 heads in a row or exactly a 50/50 split. It's called the gamblers' fallacy because it's what keeps gamblers feeding money into the slots, playing poker over their head, betting on the ponies or playing table games at the nearby casino. It's what makes losers say, "I've lost 200 quarters in a row in this slot. I must be ready to hit the jackpot."
You have to remember that every test (flipping a coin, dropping a coin in a slot or playing 29 at a roulette table) has the
exact same odds of being a winner no matter how many times you have won or lost in the past.
-- D
Quote from: Jerrys HO on October 18, 2014, 10:37:10 PM
So your saying that the 7 I purchased that all negotiate 18r the next 3 will not?
It's hard to swallow your evaluation as I believe tolerances may have a small, very small part in the equation but quality assembling is much larger. Mass production tends to have more mistakes than tolerance. I have had to loosen, tighten, or adjust to make things tolerable.
No, Doneldon actually provided a very good explanation however. Regardless of how many you buy, you have a 70% chance of getting one that runs fine on 18" radius. Keep in mind my test was of only 10 locomotives so the actual percentages could differ. It is not exactly easy to have access to more than that many locomotives unless I owned or worked at a major store like MB Klein or something.
And you are misinterpreting my use of the word tolerances it seems. To be more clear, I am stating that a given factory has a certain acceptable range for various production details and at either extreme is when you have your small percentage of locomotives that perform a little differently than the majority of the production run. In this case we were discussing minimum radius.
Speaking of Vegas, I am not accepting ACY's odds as being some sort of standard. Sorry man.
And I disagree that it is about luck; this is why I have been asking you the questions I have. The answer bears importance. Let me know how the trucks are set up to get power to the motor. All it takes is taking of the shells.
Also, I am not really sure I would take the word or advice of a LIONEL guy on an HO problem.
Re: the production tolerances and issues; this is the reason I raised the question about checking wheel gauges. I have read many times on the NET about brand new locos being received and not running properly (derailing) on the rails. Instead of checking this for themselves, people waste resources (time and $$) to send such items back instead of looking into how easily they can be repaired (really the word is 'adjusted') at home with a little gumption and effort. I am in Roger's camp when it comes to that thinking.
Doc, it is funny to see you display such knowledge about gambling and odds, from a guy who sticks his tongue in live lamp sockets... ;)
Quote from: jbrock27 on October 19, 2014, 08:03:21 AM
Speaking of Vegas, I am not accepting ACY's odds as being some sort of standard. Sorry man.
And I disagree that it is about luck; this is why I have been asking you the questions I have. The answer bears importance. Let me know how the trucks are set up to get power to the motor. All it takes is taking of the shells.
Also, I am not really sure I would take the word or advice of a LIONEL guy on an HO problem.
You don't have to believe me. All I know is I had the opportunity to test run 10 Bachmann 2-8-0 locomotives. All the wheels were found to be in guage by the way. No issues or differences could be observed with the naked eye. Some measurements were taken and all measurements were consistent within 1/16th of an inch between the models. Perhaps this 1/16th of an inch variability is what accounts for the differences in performance.
Until you or someone else can obtain or knows a way to obtain more than 10 locomotives to test, all we can go off of is what was found in the test I conducted with 10 Bachmann consolidations.
As far as it being ill advised to take the word of my friend who was with Lionel at the time, I am offended by that statement because you have no knowledge of his experience or background. He actually worked a great deal with HO scale, before Lionel made him a job offer he could not refuse. Even though he worked for Lionel, he actually had a large HO layout at his home.
The data is what it is, 3 out of 10 did not run on 18" radius, 7 out of 10 ran without any problems. After doing some statistical calculations, the tests show that with 98% certainty at least 10 out of 100 units will not run on 18" radius or with 99% certainty at least 5 out of 100 units will not run on 18" radius.
Sid;
Great job of building those cars. Like you, I am going to try the Tichy trucks; only with Kadee wheels. I am using the ribbed 33" wheels.
I also decided to unload the #5s I had in stock. They won't be coming apart, so why not? I will have two of the "BACHMANN"...Moguls working the magnesium quarry and processing plant.
Rich
ACY, it is not that I don't believe you, I do. What I don't believe is that it is problem that cannot be explained or better yet, corrected. You have yet to take the time to answer my questions I put forward to you, but are taking the time for this back at forth. I don't know why. Suit yourself. You did say you put speakers in these Athearn SD45s-you don't remember what you saw when you took the shells off??
If you would like to be so thin skinned as to take offense, that is your choice, just as it is to assume what you are saying to be an absolute, when others have stated they have had a different experience. Why would what YOU have to say about the matter, be treated as more meaningful than when someone else says they have had the opposite experience?!?
You're right, I don't know your LIONEL boy's background. But what I do know, is I don't have any problems running the 3 six axle diesels we have on 18"R curves.
Quote from: jbrock27 on October 19, 2014, 04:20:40 PM
ACY, it is not that I don't believe you, I do. What I don't believe is that it is problem that cannot be explained or better yet, corrected. You have yet to take the time to answer my questions I put forward to you, but are taking the time for this back at forth. I don't know why. Suit yourself. You did say you put speakers in these Athearn SD45s-you don't remember what you saw when you took the shells off??
If you would like to be so thin skinned as to take offense, that is your choice, just as it is to assume what you are saying to be an absolute, when others have stated they have had a different experience. Why would what YOU have to say about the matter, be treated as more meaningful than when someone else says they have had the opposite experience?!?
You're right, I don't know your LIONEL boy's background. But what I do know, is I don't have any problems running the 3 six axle diesels we have on 18"R curves.
1. I installed sound in the one SD45 in 2006 or 2007. I don't recall exactly. I currently have most of my locomtives and rolling stock in storage, so checking won't be easy.
2. What I have to say or another person on the forum has to say holds equal weight, perhaps their opinions should be more highly regarded. However, what I posted was not an opinion; it was the results of the tests that were performed on 10 Bachmann consolidations.
3. The person who was with Lionel is in his seventies and now retired as far as I know. Also I have not been discussing 6 axle diesels specifically. I only cited the results of the tests performed on the consolidations as an example.
You are more than welcome to perform your own tests on a larger sample size and see if you get contrasting data, or data to support your opinion in other words. I used statistical calculations on the 10 consolidations I tested to find that at a bare minimum at least 5% or up to 40% can have issues running on 18" radius from that given production run. I utilized a 2 tail t-test on my data to obtain these results.
I would share the full results if I could but I spilled water on my keyboard this afternoon so my computer is currently not working so I have to send it in for repair most likely.
I set up an oval with 18r. I ran 3 SD40-2's, 3 SD45's, 1 SD70 for 10 laps each.
None derailed or had any problems.
Does this mean I can assume that 100% of the SD's I purchase will run on 18r or just 70%?
I still back JBrock unless I happen to stick my wet finger in a light socket ::).
It all depends on track work and how well the engine and rolling stock are in gauge and adjusted. I may believe 1% of loco's and rolling stock are a little out of tolerance, 30% and there would be a lot more problems than this thread has noted.
Quote from: Jerrys HO on October 19, 2014, 07:54:16 PM
I set up an oval with 18r. I ran 3 SD40-2's, 3 SD45's, 1 SD70 for 10 laps each.
None derailed or had any problems.
Does this mean I can assume that 100% of the SD's I purchase will run on 18r or just 70%?
I still back JBrock unless I happen to stick my wet finger in a light socket ::).
It all depends on track work and how well the engine and rolling stock are in gauge and adjusted. I may believe 1% of loco's and rolling stock are a little out of tolerance, 30% and there would be a lot more problems than this thread has noted.
I conducted the tests without rolling stock. If you are able to test more than 10 identical locomotives (from the same production run), then your results will have statistical significance. I was barely able to establish any statistical significance with 10 identical locomotives. That is why with my results I was only able to establish with 99% confidence that 5% would perform in this manner even though 3 out of 10 did in my tests. The larger the sample size, the greater the significance of the results and this directly impacts the confidence interval and other related statistical data.
The tests were performed on 3 different 36" circles of Bachmann EZ track each assembeled multiple times. The track was brand new from three different sets I had purchased recently. An NMRA standards gauge was used to check to make sure all the wheels were in guage.
Although it would be easy to say that a certain locomotive had this or that problem that could be rectified; you will have to trust my word that no issues or differences could be found. I would not trust my ability, which is why I relied on others assistance to ensure nothing was missed or overlooked.
Also consider that many people and clubs have layouts with 22" minimum radius or larger so even though a certain percentage may have trouble with 18" radius, it is possible many people never knew since they never attempted to run their locomotive on anything less than 22" radius. Or even possibly 20" radius if they use flex track.
It would be nice to have the opportunity to perform a larger test with a sample size, but it would be very time consuming and difficult.
Alright everyone, we're straying away from the question. to the OP: I would still recommend the 2-8-0, its a popular locomotive, easy to find, and nice looking. That is for steam. Diesel-wise I'm partial to the Geeps but I don't model Diesel.
Regarding odds, to weigh in on this 30/70 thing, if we expand the sample size and look at the possible range, we learn that it is impossible to predict. for example, lets assume that the inability to run on 18 is a defect caused by some miniscule and hard to notice wheel eror in manufacturing. Lets also assume a run of 5,000 for ease. ACY said he tested 10 and 3 failed right? well that is 30% of the tested but if we look at the sample, it could be that 4993 were correct, or it could be that 7 were and 4993 weren't the fact is, we have no way of knowing FOR SURE. Furthermore, even if we take it as a proper representation, the whole "i have 7 so the next three must be bad" doesn't work, not only because of the aforementioned Gamblers fallacy, but because we are testing from drawing one out the the pool of locomotives. even takign the (ridiculously high) failure rate of 30%, that means that there were 3500 good ones and 1500 bad ones. Youd odds are ACTUALLY based on the 3493 remaining good ad 1500 remaining defective (since we do not know where they went) meaning you STILL have a higher chance of pulling a good one. but since there could be 3-4993 bad ones per run, we cant say.
Fun fact, my grandfather used to work in the Lionel repair shops in NJ. Oh the stories he's told.
I just wonder what percentage was built on Monday and what percentage was built on Friday ;) ::) ??? ;D.
ACY, I don't need to run any tests or produce any statistical data to support what I know and experience-no problems running 2 SD45s, 1 SD9 and 1 SDP40 (all Athearn) on 18"R curves, 100% success. If you would like to send me some locos to try out for further testing/fixing I would be glad to check them out and run some tests. Also, if you ever take the time to bother taking those SD45s you have outta storage, get back to me.
It is unfortunate that you are still missing the boat here; you have had your problems running the same locos that others here have reported having no problems running, on 18"R curves. That should tell you something, but somehow, it is not, nor does it look like anything said is going to change that for you.
**Please note, I am not making any statements here about Consolidations, nor have I in any prior posts.
I just wonder what percentage was built on Monday and what percentage was built on Friday
Yea, I heard about that kinda thing ::). In the spirt of Halloween, I wonder if any of those bad locos, had serial #s that ended in : 666 :o
Jim-
As part of my main vocational training as a clinical psychologist I had to take a load of statistics and experimental design classes -- enough that I have the equivalent of a master's degree in statistics. That's how I'm able to look at ACY's data and discuss the gambler's fallacy.
ACY-
I found your statistics on the go/won't go question about Bachmann Consolidations on 18-inch radius curves to be interesting and worth playing around with. However, your more recent post reveals that you are taking what are essentially anecdotal findings and attempting to predict from them. Your data do not support that. Further, your recent use of that data demonstrates a lack of understanding about how to use statistics and how to properly design an experiment. Let me try to help.
You need to be careful of interpreting results beyond what your data show and, especially, reporting post hoc confidence limits. Yes, I know that rule is routinely violated in the academic literature of many disciplines, including psychology at times, but the most rigorous journals still don't allow it. That's part of why certain journals are so prestigious; they have high standards and they stick to them.
Your sample is so small and uncontrolled as to be intriguing but not meaningful. The size of your sample, as well as its lack of stratification, renders it worthless for predicting anything about the entire population of Bachmann 2-8-0s. There are just too many parameters for which you haven't controlled. For example, do you know if all of your Connies were built in the same factory by the same workers? Do you know how long each sat in storage in a Chinese warehouse, U.S. warehouse, distribution center or retailer's back room? Do you know if any of your locos were subjected to unusual treatment during shipping? Do you know if any construction changes were made or whether each of the locos was built to precisely the same plans as part of a single production run? Do all units have the same kind of lubrication as well as the same amount? Did you test to see if the tension on the front truck screws was the same for every unit? How about the resilience of the springs on those pilot trucks? Were all of the locomotives broken in to the same degree? Did they all have the same amount of running time? And what about the track? Did you institute any systematic differences when you assembled, disassembled and reassembled the track? Did each circle you constructed have exactly equally tight joints and alignment? What about the coefficients of friction for the rails and wheels; were they all the same? There are many more.
You stated that all specifications which you measured were within 1/16 inch. You do realize that's the equivalent of nearly five-and-a-half-inches on the prototype. I have to say, I'm not impressed with measurement which are as great as 1/16 inch on something as small as an HO model, particularly when we are discussing running gear and its performance.
It's a fundamental statistical error to predict beyond one's sample unless that sample was appropriately constructed. Your sample is so small and so uncontrolled that you really can't generalize from it at all. Yes, I kind of did so when I was explaining the gambler's fallacy but I wasn't asserting any meaning beyond your findings.
You have another problem, too. One does not run the study, do some statistical analysis and then go to a statistics book to see what confidence limits were met. That is just a terrible misuse of the results. The way it is supposed to be done is one develops an experimental design with the expectation that there will be no differences (the null hypothesis), one recruits a carefully selected sample of a size that enables one to extrapolate beyond the sample findings at a degree of certainly which is determined a priori, the subjects are run, and a statistical analysis is completed to see if the null hypothesis can be rejected. Do I expect you or anyone else on this board or at Bachmann's to do this kind of rigorous testing? Of course not. But I'm not comfortable seeing someone present data as if it were appropriately derived when it clearly was not.
All of that said, I wouldn't be at all surprised to find that your 30% won't go around 18-inch curves is pretty close to the truth. And if it is, I believe it would behoove Bachmann to look at their engineering to see why some Connies can handle tight curves while others cannot.
-- D
Don, I must say, you really know your statistics. And like I said before with the circumstances I did the best I could with what I had to work with. Some of the things you mentioned were controlled for bit many were not and of course many variables were unknown. But it would be extremely difficult for the average person to do much better than I did. To conduct a statistical analysis in the manner you suggested would be next to impossible unfortunately. That is why I had to make a few assumptions about unknowns and also work hard to try and extrapolare any information from the data recorded.
To all, I said all along I doubt it affects 30%, but I would not rule out it affecting 5%-10% of the production run.
One piece of information I find interesting is that my friend who was with Lionel would test about a hundred locomotives a day on a set of 8 patallel tracks and begins on the most gradual radius and gets progressively sharper on the inside, he would take note of what the sharpest radius the locomotive could negotiate was. For a certain O scale Lionel locomotive, (I can't recall which anymore), he observed that roughly 90% could negotiate O-27 while the other 10% could not. His sample size was a few thousand locomotives. So even though my sample size was not nearly as large, the findings are in the ball park of a much larger study involving Lionel O scale locomotives. He said the issue was most likely related to the mass production of the locomotive in a factory with less than desirable QC, however the factory is still used because it has lower costs than otger factories with more QC and consistency throughtoutthe whole production run. In fact, Lionel produces model Nascar cars in two different factories, the model cars are marked slightly differently on the bottom but are otherwise identical. However, the cars marked from the one factory tend to have errors in the decal placement orthe paint or other details while cars from the other factory are without any noticeable flaws.
So it could be ppossible Bachmann utilized multiple different factories or tooling which caused minor variations in the ptoduction quality. Regardless I still find Bachmann to be the most reliable and detailed locomotives and at an excellent price point. Bachmann locomotives are a good reliable product especially considering how many units they have to make of each locomotive.
my main vocational training as a clinical psychologist
D, I know, this is why I refer to you as "Doc". Another impressive item on your resume, or curriculum vitae if you will. I don't doubt for one second you are more qualified to discuss statistics.
Comparing O Scale to HO Scale? Sounds like comparing apples to oranges to me. But what do I know? I don't have any data to ramble on about, just what I see in operation.
ACY-
I understand that it really isn't feasible to do a fully controlled, properly constructed experiment to determine the proportion of
Bachmann locos which can negotiate 18" curves, or any other characteristic for that matter. I was just making the point that we shouldn't
accept what data we do have, like your informal little survey, as though it were developed with the kind of rigor needed to make such
predictions.
-- D
Last time I used an 18" radius curve on a running line was on my teenage Hornby Dublo railway.
Since then it's been either hand laid or this time around, flex track. Smallest radius 30" on running lines.
However, my old GER did have a 20" (roughly) radius leg on the wye in Berger Yard that was used for turning engines. In view of the 20" radius on the wye, the largest engines used on the branch up to Berger Yard were 2-8-2 and as the 20" radius leg was the farthest from the aisle, the 2-8-2s looked acceptable from the aisle viewing angle. My current GER has an 18", roughly, curve in the industrial area serving as the lead to the J. King & Co. warehouse. This curve is currently switched by an 0-8-0 but will eventually be switched by an 0-6-0, once the 0-6-0 is equipped with a DCC sound decoder. See curve here, scenery still nowhere near completed: -
(http://i94.photobucket.com/albums/l99/rogertra/The%20new%20Great%20Eastern%20Railway/IMG_0374_zps4616bb3f.jpg) (http://s94.photobucket.com/user/rogertra/media/The%20new%20Great%20Eastern%20Railway/IMG_0374_zps4616bb3f.jpg.html)
I realise that some people have space issues but I would still try to avoid 18" curves on running lines and shoot for 24", just because medium sized equipment just doesn't look "right" negotiating curves as tight as 18" and larger engines and passenger cars look, well, really "odd".
Cheers.
Roger T.
Quote from: Doneldon on October 20, 2014, 10:27:36 PM
ACY-
I understand that it really isn't feasible to do a fully controlled, properly constructed experiment to determine the proportion of
Bachmann locos which can negotiate 18" curves, or any other characteristic for that matter. I was just making the point that we shouldn't
accept what data we do have, like your informal little survey, as though it were developed with the kind of rigor needed to make such
predictions.
I understand your view on my findings, but what we do know is some percentage of many HO locomotives will not be able to negotiate 18" radius curves even though the majority are capable. And the only cause in many cases is due to variation present in mass production runs. I still think it is reasonable to believe that some small percentage such as 1% may be affected. But beyond that I probably shouldn't speculate. However I am working with a friend who may be able to facilitate a larger scale analysis of around 100 identical locomotives but even that may not be sufficient unfortunately. So I am holding off for now until I figure out what sample size would be necessary to perform a statistical analysis that holds more weight so to speak.
Thanks to all,
The info contained in these replies has convinced me. Going to a combo of 22 and 18 and stick with the 2-6-0 steam and the four axel diesels until I can shake loose more space in the basement. For now 22 outside and 18 inside(two ovals) on a 4x8 platform.
thanks Gene
It's certainly the conservative play with regard to the diesels. You should have no troubles from the 4 axle ones. I can't comment on the 2-6-0 steamer since we don't have any.
Good luck and have fun :)
the 2-6-0- will work on 18r with no problems. I have both the standard line and the alco 2-6-0 and have no trouble with them. you can also run a small 2-8-0 like the roundhouse one with no problems. btw, if you can find one, the roundhouse 2-8-0 is a gutsy puller, mine will pull 10 cars or more around 18r on a 4% upgrade.
one thing I have found is that steamers tend to be pickier on track than diesels, due to the rigid wheelbase of the drive wheels. it is best to make sure all your rail joints are level. sometimes the rail ends are bent slightly up or down, the resultant hump or dip can cause derailment problems. this can be easily corrected by leveling the joint and soldering it so it stays level. the problem is most severe on the outside rail of a curve.
Dear Rielag,
Here is a thread with a 18"-22" dual-oval 4x8 pictured:
http://www.bachmanntrains.com/home-usa/board/index.php/topic,12474.0.html
Hope this Helps.
Sincerely,
Joe Satnik
Thanks all. I found a 4x8 on "layoutvision.com" that I will probably go with.
Fall Mills RR. Does not look to difficult and it fits my current space requirement.
Gene
Quote from: ACY on October 21, 2014, 04:52:40 AM
I understand your view on my findings, but what we do know is some percentage of many HO locomotives will not be able to negotiate 18" radius curves even though the majority are capable. And the only cause in many cases is due to variation present in mass production runs. I still think it is reasonable to believe that some small percentage such as 1% may be affected.
ACY-
I don't disagree with your findings; my concern was generalizing from faulty data to the overall population of Bachmann locomotives. And, I think we actually agree as to the principle; there is a certain percentage of locomotives which vary so far from their intended circumstances that they don't perform the same as the models which do conform. Notice that I didn't say better or worse. I just mean different. After all, some variance from the ideal or the average can be desirable. If we didn't have people who could do things with some colored goop and a paint brush, we wouldn't have any of the world's beautiful art to enjoy. Or wonderful, creative, realistic model railroads to inspire us in our own modeling endeavors.
-- D
Quote from: Rielag on October 21, 2014, 07:25:28 PM
Thanks all. I found a 4x8 on "layoutvision.com" that I will probably go with.
Fall Mills RR. Does not look to difficult and it fits my current space requirement.
Gene
that railroad is designed using atlas switches, and flexible track. note the odd radii on the plan. if you want to build it using ez track you will have to redesign it.