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Grade Down To A Quarry

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Grade Down To A Quarry
Posted by caldreamer on Sunday, August 27, 2017 3:49 PM

Would a 4.6 percent grade be too steep going down to a rock quarry?  The branch comes off a main track, down over a high trestle through two tunnels to the loading tipple.  I was planning on pulling three or four hoppers/flat cars at a time up the grade with two 4 axle diesle units.

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Posted by BMMECNYC on Sunday, August 27, 2017 4:07 PM

caldreamer

Would a 4.6 percent grade be too steep going down to a rock quarry?  The branch comes off a main track, down over a high trestle through two tunnels to the loading tipple.  I was planning on pulling three or four hoppers/flat cars at a time up the grade with two 4 axle diesle units.

 

That would depend if the two 4 axle diesel units could pull the desired length train up the grade specified.  You should mock up the grade and test your consist prior to committing to the design.   If you have a curve in your 4.6% grade, your effective grade will be somewhat more than what you had planned.

Rule 108: In case of doubt or uncertainty, the safe course must be taken.
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Posted by selector on Sunday, August 27, 2017 4:23 PM

I agree with the previous gentleman.  You could approach this in one of two ways:

Just keep adding power until your grade is conquerable; or

Limit the grade to what you know your locomotive power can handle.

In the first case, you may run out of switching room if you need three engines and can't clear the points rearward.  Or, if you only shove the cars ahead of the power, will their number foul other operations rearward, say on a shared switchback or something.  These may not seem terribly consequential, but it all really depends on what you want in the way of concurrent ops....on that section of switched track.

In the second case, you may end up managing only 4.0%, in which case you could be faced with rather drastic modifications of your dream track plan.

Decisions, decisions...

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Posted by doctorwayne on Sunday, August 27, 2017 4:36 PM

I have a 4% grade beneath my staging yards, which affords continuous running on my normally point-to-point layout.  This is useful when visitors come and simply want to see some trains run.  A Bachmann Consolidation can handle at least a dozen cars on the grade, so 4.6% shouldn't be a problem for even one diesel if you're pulling only three or four cars.

The grade from the Sifto salt mine at Goderich, Ontario, up to the yard of the Goderich & Exeter Railway is about 4%, so 4.6% isn't all that unprototypical for such an operation.
Here's the visible part of the mine, the world's largest underground salt mine...

...the rest of it is under Lake Huron.

Wayne

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Posted by davidmurray on Sunday, August 27, 2017 4:46 PM

I built an iron ore mine.

I used Woodland Scenics 4% grades to go up two inches, the a turnout/switchback and up another two inches.

By blue box diesels haul five iron ore cars and a caboose, or three general service car up to the mine.  The switch back prevents more.

NO curves on my setup.

Better engines should no more.

Dave

 

David Murray from Oshawa, Ontario Canada
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Posted by caldreamer on Sunday, August 27, 2017 5:09 PM

I am in N scale and use the protoype tractive effort to calculate the tonange raing for all of my locomotives.  For example a GP40 is rated at 84 grems of tractive effort up a 4.66 percent grade.  This is equivelant to over three 40 foot hoppers.  Even with the long sweeping curve between the high trestle and the quarry, two 4 axle units should work.

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Posted by cuyama on Monday, August 28, 2017 7:20 PM

caldreamer
I am in N scale and use the protoype tractive effort to calculate the tonange raing for all of my locomotives.

From a practical standpoint, the pulling power of models varies tremendously by model and manufacturer and doesn't relate to the tractive effort of the prototype at all. I have models of relatively small N scale switchers that out-pull models of larger mainline engines.

If you wish to know how what you are proposing will work, mock it up. Good vertical transitions will make it more likely to work.

 

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Posted by caldreamer on Monday, August 28, 2017 7:47 PM

I have tried this forumula on multiple types of engines manufactured by many of the N scale manufactureres and it works well. 

Prototype tractive effort / N scale(160) / grade = tractive effort in grams of tractive effort

 GP40 = 62500 lbs tractive effort / 160 / .015 (1.5 percent grade) = 163 grams or

5.821428571 oz of tractive effort.

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Posted by cuyama on Monday, August 28, 2017 8:03 PM

caldreamer
I have tried this forumula on multiple types of engines manufactured by many of the N scale manufactureres and it works well.  Prototype tractive effort / N scale(160) / grade = tractive effort in grams of tractive effort  GP40 = 62500 lbs tractive effort / 160 / .015 (1.5 percent grade) = 163 grams or 5.821428571 oz of tractive effort.

That calculation doesn't really make practical sense, but if it makes you happy, great. My Atlas VO-1000s pull better than N scale models of engines with higher horsepower. So there's that.

Carry on.

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Posted by caldreamer on Tuesday, August 29, 2017 8:38 AM

True the Atlas VO1000 may pull greater than its protypical tonnage rating, but to run protpically I use the formula that I posted.  If I have a train that weighs 600 grams I would need three locomotives rated at least 200 grams each to pull the train up the grade.  My old ConCor/Kato U50B will pull 450 grams up a 2.65 percent grade at less than half throttle without any problems.  Protoypically it is rated at 377 grams of trative effort.

 

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Posted by NVSRR on Tuesday, August 29, 2017 10:02 AM

I remember reading about a guy who removed weight from locomotives to give them more prototypical scaled pulling ability.   Along with a formula To work in ozs.  Apparently worked well To create prototype pulling conditions

 

Wolfie

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Posted by Doughless on Friday, September 01, 2017 9:27 AM

I think most quarries would convey the material up to the flat surface rather than building tracks down the sides at an excessively steep grade.  The railroad loading tipples aren't necessarily right next to the quarry pit. Maybe you could model more conveyors and have less to worry about for track incline.

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Posted by doctorwayne on Friday, September 01, 2017 11:32 AM

Doughless

I think most quarries would convey the material up to the flat surface rather than building tracks down the sides at an excessively steep grade.  The railroad loading tipples aren't necessarily right next to the quarry pit. Maybe you could model more conveyors and have less to worry about for track incline.

 
Good points, but it sounds as if the access track (or at least the planning for it) is already in place...

caldreamer

Would a 4.6 percent grade be too steep going down to a rock quarry?  The branch comes off a main track, down over a high trestle through two tunnels to the loading tipple.  I was planning on pulling three or four hoppers/flat cars at a time up the grade with two 4 axle diesle units.

 
As I noted in my earlier post, such a grade is not unprototypical, and, while I've not been there when the mine was being switched, I've read an account of several geeps (various models) being required to move a cut of loaded hoppers up that grade.
 
Wayne
 
 
 
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Posted by mlehman on Saturday, September 02, 2017 5:29 AM

Doughless
I think most quarries would convey the material up to the flat surface rather than building tracks down the sides at an excessively steep grade.

For crushed stone, yes, But then there's cut stone, like the blocks the Monon hauled in quarry-to-mill service in the Bloomington, IN area. We lived right across the road from a mill on the Maple Hill Branch on the southwest side.

IIRC, no real grade down into the quarry there, but there were in other quarries. Instead, the RS-2 usually used had to go uphill to the quarry itself, couple, then ease the flats downgrade to the spur into the mill. With the hills in southern Indiana, the local geography determined the best entrance into the quarry, could be up down or sidewaysSmile, Wink & Grin

Another famous "uphill" quarry entrance is to the quarry at Marble, Colorado. Thought it was by rail, but only found a steam road tractor pic. It's extreme and IIRC there was a cable tramway involved. Anyone know?...

OK, now found what I needed. The cable tramway lowered the blocks to a loading station below the quarry mouth. There, blocks were transferred to RR flats, which were moved by an electric locomotive that braked the loads (and probably fed massive amounts of regenerated power back into the wire) on its way down. It's all rather steep...

 

Mike Lehman

Urbana, IL

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Posted by BRAKIE on Monday, September 11, 2017 7:49 AM

Doughless

I think most quarries would convey the material up to the flat surface rather than building tracks down the sides at an excessively steep grade.  The railroad loading tipples aren't necessarily right next to the quarry pit. Maybe you could model more conveyors and have less to worry about for track incline.

 

Exactly since the stone will need to be process and crushed before loading into hopper cars.

Even today rail served quarries has a switcher to pull the cars through the loadout and on to the interchange track. Big quarry trucks haul the stone to the processing/crusher building from the pit.

Larry

SSRy

Conductor

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