Stevens Pass Centerbeams seem overly heavy

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Stevens Pass Centerbeams seem overly heavy

Unread postby CGrimes » Mon Mar 31, 2014 12:08 pm

Has anyone noticed that the Steven Pass centerbeam flat cars need an awful lot of power to get them moving?

I had to put 8 CS44's on a 53 car train to get it up Steven's Pass and still could not maintain 20 mph.

The weights as shown for a loaded StP Centerbeam is 94t loaded & 31t unloaded in Quick Drive consist editor.

The Weights for Marias Pass Centrebeams are 39t loaded & 17t unloaded.

Quite a difference!

CG
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Re: Stevens Pass Centerbeams seem overly heavy

Unread postby thecanadianrail » Mon Mar 31, 2014 3:11 pm

Well a real centerbeam flatcar loaded would weight in around 100t in real life so the weight isn't really off in the measurements. Im not sure why 8 ES44's couldn't pull that short train over the hill, which ES44's were you using?
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Re: Stevens Pass Centerbeams seem overly heavy

Unread postby CGrimes » Mon Mar 31, 2014 3:22 pm

thecanadianrail wrote:Well a real centerbeam flatcar loaded would weight in around 100t in real life so the weight isn't really off in the measurements. Im not sure why 8 ES44's couldn't pull that short train over the hill, which ES44's were you using?


I'm using the Steven Pass Route ES44's.

You are right according to BNSF (http://www.bnsf.com/customers/equipment/centerbeam-flatcar/) a 60 foot Centerbeam Flatcar can hold up to 100 tons.
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Re: Stevens Pass Centerbeams seem overly heavy

Unread postby Ericmopar » Tue Apr 01, 2014 3:21 pm

If I remember correctly, rule of thumb is to double horsepower and tractive effort for every 1% increase in grade. That would be logarithmic I think.
So, a train that needs 8000hp on level ground, would need 16000hp on a 1% grade, and 32000hp on a 2% grade and so on.
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Re: Stevens Pass Centerbeams seem overly heavy

Unread postby thecanadianrail » Tue Apr 01, 2014 4:13 pm

Ericmopar wrote:If I remember correctly, rule of thumb is to double horsepower and tractive effort for every 1% increase in grade. That would be logarithmic I think.
So, a train that needs 8000hp on level ground, would need 16000hp on a 1% grade, and 32000hp on a 2% grade and so on.


this page will answer all of that: http://www.alkrug.vcn.com/rrfacts/hp_te.htm
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Re: Stevens Pass Centerbeams seem overly heavy

Unread postby Toripony » Tue Apr 01, 2014 8:03 pm

This is just an observational reference... here in Oregon south of Eugene I routinely see short (25-30 car) loads of finished wood products pulling hard up grades around 2-3% using 2 heads and 1 pusher.
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Re: Stevens Pass Centerbeams seem overly heavy

Unread postby thecanadianrail » Wed Apr 02, 2014 1:18 pm

Toripony wrote:This is just an observational reference... here in Oregon south of Eugene I routinely see short (25-30 car) loads of finished wood products pulling hard up grades around 2-3% using 2 heads and 1 pusher.


Now this is interesting! Out here I will usually see a lumber train (mix of centerbeams and boxcars) of around 70-100 cars long going through the mountains on the CN mainline usually with only 1-2 locomotives. Granted the track doesn't quite hit 2% at its max but it still has a fairly steady grade between 1-2%. So now im left wondering what is correct?
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Re: Stevens Pass Centerbeams seem overly heavy

Unread postby buzz456 » Wed Apr 02, 2014 2:00 pm

It's not just grade but curves.
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Re: Stevens Pass Centerbeams seem overly heavy

Unread postby FourEightFour » Wed Apr 02, 2014 9:22 pm

You could utilize the Cole formula:

Rolling resistance: 8 lbs per ton
Grade resistance: 20 lbs per ton per percent of grade
Curve Resistance: .8 lbs per ton per degree of curvature


Disclaimer: I use this for older equipment, as that is all I have to work with.
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Re: Stevens Pass Centerbeams seem overly heavy

Unread postby Ericmopar » Wed Apr 02, 2014 10:11 pm

The number of engines will also depend on what the railroad considers a tolerable line speed up the grade.
It also has to do with drawbar pull. If the train has enough power to get up the grade, but not enough DSP units to keep a drawbar or knuckle from breaking, they add units for that too.
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Re: Stevens Pass Centerbeams seem overly heavy

Unread postby GreatNortherner » Thu Apr 03, 2014 12:31 pm

Hi,

It's been my experience in RW that train weight and engine power usually result in maximum gradient speeds that are generally close to what Al Krug's tool calculates. I have also observed that many of the, especially older, US DLC cars are underweight in loaded state (if they can be loaded at all), which might contribute to the surprising effect when suddenly switching to cars with heavier loaded mass.

Link to Al Krug's RR Forces Calculator: http://www.alkrug.vcn.com/rrfacts/RRForcesCalc.html

Cheers,
Michael
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Re: Stevens Pass Centerbeams seem overly heavy

Unread postby ErikGorbiHamilton » Sat Apr 05, 2014 10:54 pm

ES44's in real life are really "Under Powered" when it comes to mountains
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Re: Stevens Pass Centerbeams seem overly heavy

Unread postby BNSFdude » Tue Apr 08, 2014 3:23 pm

BNOV2 wrote:ES44's in real life are really "Under Powered" when it comes to mountains

As a conductor, I may be over stepping my bounds of knowledge of train handling, but under what authority do you make this (false) statement? And what specific ES44 are you talking about? DC? AC? C4? They all have different characteristics from my experiences.
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