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Author Topic: Bachmann Locomotives limited to 2 degree grade????  (Read 18169 times)
ftherrmann

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« on: May 09, 2012, 12:41:45 PM »

I recently purchased a 81661 USRA 4-8-2 locomotive.  Despite still having both its traction wheels it has “absolutely” no pulling power.  I have a 3 deg incline in my layout and this locomotive “spins” it’s wheels WITHOUT any rolling stock attached. If you attach two small cars it basically stops and spins. I have some of the other smaller, non-spectrum locomotives and they have at least 10 times the pulling power of this locomotive.

I also tried "Bullfrog Snot" in an attempt to get more traction.  The "Snot" improved things a little, but the locomotive is still basically useless for my layout.

I spoke with one of the Bachmann service people and they told me that Bachmann locomotives are limited to a two degree incline.  I didn’t find this stated anywhere when I purchased it back in Feburary.  I also don't find this to be the case with other Bachmann locomotives which are even smaller than this 4-8-2 and have at least 10 times the pulling ability.  If a 2 degree incline limitation is indeed the case shouldn't Bachmann state this in their marketing material?

Being limited to a 2 degree grade would mean that in order to have any type of over passes you'd have to have an enormous layout.  Most likely twice the size of a typical 4x8 ft N scale layout.

I've returned the loc back to Bachmann hoping for either a comparable loc replacement or finding a fix for this useless 4-8-2 loc.

Please tell me that this 2 degree limitation isn't true...
 
Fred
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jonathan


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« Reply #1 on: May 09, 2012, 01:28:47 PM »

Fred,

I have two 4-8-2s.  Neither came with traction tires.  Is this an HO scale locomotive?  None of my Bachmann locomotives have traction tires.  Oops; the standard 4-4-0 has 'em.

My 4-8-2s are among my best pullers.  The metal boiler gives them good weight over the drivers.  I have not found it necessary to add weight or traction. 

Confused...

Regards,

Jonathan
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2-8-8-4

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« Reply #2 on: May 09, 2012, 01:33:26 PM »

First--Original Poster--are you talking degrees or percent of grade, because there is a significant difference between the two?

A 2-degree grade is actually 3.49% (100% times the rise in inches divided by run)--which is more than most railroads ever had on a mainline.

A 3-degree grade is actually 5.24%--and most engines, real or model, should be spinning on that grade.

Actually, in the model world we generally expect our engines to pull way too much relative to the grades we have than the prototype engines could.

Second--I absolutely despise traction tires in general because they become a maintenance headache in the long run that can also affect the durability of the steam engine valve gear (increased stresses and wear patterns on the valve gear).

I am very thankful Bachmann chose to leave traction tires off the 2-6-0 and 2-8-8-4, and if the cars are properly weighted and roll properly, my 2-6-0's are pulling an adequate length of train.

John
« Last Edit: May 09, 2012, 01:39:07 PM by 2-8-8-4 » Logged
ftherrmann

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« Reply #3 on: May 09, 2012, 01:59:27 PM »

When the customer service rep made the statement she made no distinction between scale.  Based on this I assume it applies to all scales.
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wildpaws

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« Reply #4 on: May 09, 2012, 02:46:01 PM »

When the customer service rep made the statement she made no distinction between scale.  Based on this I assume it applies to all scales.

Which still leaves the question unanswered, is your loco HO scale or N scale? If it's N scale, why would you be asking in the HO forum??
Clyde
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2-8-8-4

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« Reply #5 on: May 09, 2012, 03:03:11 PM »

Also--if you are calculating the distance required for one track to get up over another track, there are tables in some of the better layout books that do that for you.  However, the key criteria are how much elevation difference do you want between railheads?  And how thick is the overpass bridge (because that thickness must be subtracted from the elevation difference in order to calculate the maximum height of rolling stock that one can allow on the layout)?

And yes--a simple figure 8 up and over layout for modern (excess height) freight cars might possibly fill an entire 4' X 8' or 5' x 9' in HO--depending on the clearance chosen.

That's also why layouts the run along an exterior wall--with return loop(s) somewhere in a room to allow continuous running--might be preferred for "permanent" layouts.  They also take up less overall floorspace from a room, but require more complicated design and construction than the good old 4' x 8'.

I know that designing for "modern" equipment and/or full length passenger cars is all but impossible on a standard 4' x 8'.  That is reality in HO.

John

« Last Edit: May 09, 2012, 03:05:11 PM by 2-8-8-4 » Logged
richg
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« Reply #6 on: May 09, 2012, 03:11:21 PM »

For those who did not look it up, 81661 is an N Scale loco. No idea if it comes with traction wheels.

Rich
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Doneldon

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« Reply #7 on: May 09, 2012, 03:26:25 PM »

Rich-

Thanks for looking up the scale. I had noticed that the OP avoided that question. However, and to his credit, it doesn't look like he has multiple posts on the issue. Perhaps he's new to model railroading and doesn't understand what grades do to locomotives' pulling capacity. Even allowing for all that, it does seem that his loco is a little anemic. I'd like to know what it will do on level track.
                                                                                                                                 -- D
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bobwrgt

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« Reply #8 on: May 09, 2012, 05:56:58 PM »

Dear Fred

If you do a search in the N scale section you can find lots of information on the N SCALE light mountain not pulling it's weight. There are several solutions to the problem.

Bob
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Jim Banner

Enjoying electric model railroading since 1950.


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« Reply #9 on: May 09, 2012, 09:29:18 PM »

If it is pulling power you want, stick to diesels.  A four axle diesel is guaranteed to have at least four wheels on the rails, even if climbing a twisting track on a helix.  A steamer, on the other hand, is only guaranteed to have two wheels touching the rails on the same track.  To compound the problem, a diesel has all its weight on the driving wheels while  some of the weight of a steamer is lost to the leading and trailing trucks, assuming it has them.

Things are a little different in the real world.  The drive axles of a real world steamer are not rigidly attach to a rigid frame.  Rather, they are equalized with a complex system of springs, levers and linkages so that all drivers carry about the same weight, even on twisting curves.  This has been done on some 0-scale models and possibly on some H0 models although usually springing each end of each axle is as good as it gets.  In N-scale?  Not that I have ever heard of.

Jim
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Growing older is mandatory but growing up is optional.
Rangerover1944


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« Reply #10 on: May 11, 2012, 11:25:28 AM »

A 2-degree grade is actually 3.49% (100% times the rise in inches divided by run)--which is more than most railroads ever had on a mainline.

Excuse me!
 
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http://i1150.photobucket.com/albums/o619/Rangerover1944/incline.jpg[/img]][/url

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« Last Edit: May 11, 2012, 11:45:41 AM by Rangerover1944 » Logged
Rangerover1944


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« Reply #11 on: May 11, 2012, 11:35:53 AM »

I have had no difficulty with pulling power of my 4-8-2's either with some grades that are more than 3% hauling 10 cars. I'll post pics later of my grades, no where near the prototypical that I have shown, maybe 4%, and also I have more "terrible grade prototypical pics from here in the mountains of West Virginia". I know nothing about N scale and assumed the OP was referring to HO scale! Still don't know, since no confirmation. I'm also aware that as 2-8-8-2 said in his post that most rail roads had no grade problems. Except in mountain area's, that's why some brilliant engineers came up with "switchback" to achieve the impossible impassable mountains. Jim
« Last Edit: May 11, 2012, 01:02:01 PM by Rangerover1944 » Logged
Rangerover1944


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« Reply #12 on: May 11, 2012, 01:13:09 PM »

This scenic train is still in operation today Cass Railroad Historical Society, West Virginia. Jim
[url][/url]
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2-8-8-4

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« Reply #13 on: May 11, 2012, 02:17:28 PM »

I'm also aware that as 2-8-8-2 said in his post that most rail roads had no grade problems. Except in mountain area's, that's why some brilliant engineers came up with "switchback" to achieve the impossible impassable mountains. Jim

A.  I never said that most railroads had no grade problems.  That is an inaccurate quote.  They actually had significant grade "problems".  What I said was that most mainline railroads avoided mainline grades over 3.5% due to both economic and safety reasons.  This by definition excluded logging railroads and some of those others who had little other alternative.

B.  I am a licensed professional civil engineer--and switchbacks are a horrible engineering solution, and those engineers were not what I would call "brilliant" either--they settled for the easiest, cheapest solution--perhaps they were forced to bow to the economic pressures of those railroad owners of the day.  Switchbacks involve excessive waste of time and resources to get trains up and over a mountain.  How many mainline Class 1 freight railroads still in operation today have a switchback?

To my knowledge the answer is none--I rest my case.  The economics and safety benefits of correctly designed railroad alignments put those railroads out of business--excepting some (essentially) tourist operations that remain who retain the switchbacks for scenic or other reasons--like perhaps to access the timber.

The correct engineering solution is to either tunnel through the mountain or use a series of cuts, fills, and curves to balance the grades to get them within reasonable tolerances.  Anything less is actually lazy engineering.  In the long run the operational costs of operating a poorly designed and built railroad will exceed the money saved during initial design and construction--which is why most of those railroads that featured the excessive grades are now out of everyday freight usage.

John
« Last Edit: May 11, 2012, 02:29:07 PM by 2-8-8-4 » Logged
Joe323

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« Reply #14 on: May 11, 2012, 03:03:39 PM »

There are a few railroads purposely build to go up moutains (Pikes Peak and the Carmelit Subway in Israel) come to mind but these are passenger not freight Rys 
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