# Gradient!



## gaugeonebloke (Aug 18, 2008)

Hi.

I moved house a year ago and am yet to build a line in the garden. What do you think of the following?:

130' double track oval (nice elliptical type curves) min radius 4m..that would fit on the flatter section at the bottom of the garden. I wish there was more room but there is not. 
300' single track climb at 3.3% (1 in 30) gradient min radius 3.2m up the slope including 2 loops. (the slope is more like 1 in 8)

Notionally modelled on N&W, Virginian, C&O...with the climb being a mine run or mainline Virginian

Do you think an Aster Allegheny or Accucraft Allegheny or Accucraft Cab Forward could climb the 300' 3.3% ? (I know the full size Allegheny ran on flatter grades for the most part). How about a 2-8-0 British outline freight loco. Assume use IMS rather than meths. 

Thanks for your feedback in advance,

Simon


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## deltatrains (Nov 25, 2010)

Perhaps the Live Steam gents in that forum who* own* one of those engines could help you better.
There is also the question of the number of cars you wish to pull up those grades.
All the best,
Peter.


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## Greg Elmassian (Jan 3, 2008)

That grade is tough on sparkies... it's tougher on a steamer (excepting geared locos of course) 

You might wind up double heading, but what Peter said, how long a train do you want to pull? 

Greg


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## gaugeonebloke (Aug 18, 2008)

Hi. It would be very useful to know the experiences of anyone running or trying to run up a similar grade. My guess is that 90% of locos arriving at a get-together would not make it up the grade. Many of these would have large wheels - high gearing - and would not suit the grade on principle. I think smaller wheeled locos could do it, subject to steam generation and traction constraints. Presumably a gas-fired burner could be upgraded to permit a greater gas throughput (sorry thruput!) , while I suspect space constraints with alcohol fired locos make upgrading their power source more of a challenge. Traction, especially with shiny steel wheels, will be a problem; hauling 15 J&M pullmans isn't going to happen. To answer the question posed by Greg and Peter, I would be very happy to see a loco hauling a dozen hoppers. P.S. The loco would have the benefit of a flying start from the oval.


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## Greg Elmassian (Jan 3, 2008)

By the way, get aluminum track, it has the highest coefficient of friction, much higher than brass (the oxide is basically crystals of carborundum). 

That will make a difference in slipping, now all you need is horsepower! 

Greg


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## chuck n (Jan 2, 2008)

Greg:

Corundum, (AL2O3) not carborundum (SiC)

Chuck


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## Dr Rivet (Jan 5, 2008)

Simon 

IMS??? I am sure it is some fuel used in the UK and not a reference to that shown below: 

Irritable male syndrome (IMS) is defined as a state of hypersensitivity, anxiety, frustration, and anger that occurs in males and is associated with biochemical changes, hormonal fluctuations, stress, and loss of male identity. This term covers symptoms thought to be caused by a drop in testosterone levels in male mammals. It is a striking feature in mammals with seasonal breeding patterns at the end of the mating season. 

HOWEVER, further to the original question: 

On my mainline my gradients are restricted to 1 in 176 [0.55%] with 24 foot [7.8m] minimum radius and the Aster Allegheny or Accucraft CF will pull about 60 plastic freight cars on this grade. A GS-4 can handle my 18 car brass Daylight set [about 200 pounds]. More relevant to your situation is the 90 foot lead to my steaming bay which is about 4.5% [1 in 18]. A Berkshire can push about 6 or 7 cars up the grade with a little slipping. I do not recall anyone moving a cut of cars into the steaming bay using one of the articulated locomotives. My original track had grades approaching 2.5% that ran for about 60 feet and trains were limited to about 18 cars with a Mikado. By the time the large engines began running here I had rebuilt the layout with reduced grades. 

Regarding your 3.3% grades; my intuitive sense is that a train of 12-14 cars can be handled behind an articulated. A small freight engine like the BR 8F can probably haul 6 or 7 2 axle wagons on that grade. Except that the UK style of running seems to be like most of ours [ roundy-round], I would see this as a great opportunity to put "helper pockets" at the ends of your long grade and actually have banking engines that would push a longer train up the grades. Would be quite correct for the C&O, N&W, and VGN. Also, if you have sharp curves [and 10-11 foot radius is sharp for a big engine] it will add a lot of rolling friction to the train and reduce the number of cars. 

Greg's comment not withstanding, my experience with Aluminum rail and live steam is that the steam oil makes the track slicker than owl poop, much worse than brass or nickel silver. 

Keep us posted.


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## rdamurphy (Jan 3, 2008)

Not being a live-steamer, I don't know the answer to this, but wouldn't that steep of a grade become a problem with boiler water level? Especially when the track crests and starts back downhill? 

Just wondering, Robert


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## Reg Stocking (Sep 29, 2010)

3.3% with sharp curves just may be a recipe for disaster. Southern Pacific's line over Donner Pass is at 2.18% with reductions on curves to compensate for the added drag they impose. With short trains you might make it work. 

As for boiler water problems, that depends. Small steamers generally don't have fireboxes which could suffer dry crown sheets like the big ones. But careful experimentation is in order. Good luck!


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## Dr Rivet (Jan 5, 2008)

Robert 

This is one of the challenges of live steam. On full sized locomotives there is a crown sheet on the fire box and water surrounds the fire box on the sides and top. If the water level gets low enough that the crown sheet is not covered it heats up rapidly. If water then comes back over the top it flashes into steam and often causes an explosion. 

On most models that are gas fired the burners are inserted directly into the flues and there is no fire box. Low water can damage the flues through overheating, but the usual catastrophic result is a flue collapsing on the burner which causes the fire to go out. Alcohol fired locomotives may use a firebox with a ceramic burner or a set of wicks that put heat into flues that are shorter. Coal fired models usually have a jacketed fire box that is similar to the full sized designs. However, the small grate area of the firebox and size of the boiler do not generate enough heat to create an explosion. On the other hand, the firebox and boiler could be damaged so that major repair is required. 

Bottom line... any good loco driver keeps an eye on the water glass and keeps the water level at the proper place for both safety and good operating. 

The bigger issue with a 1 in 30 gradient is keeping a train under control, especially on the down hill side.


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## Greg Elmassian (Jan 3, 2008)

Thanks Chuck, I screwed it up again ha ha... I guess I should just say aluminum oxide, just like on sandpaper... (of course SiC is also on sandpaper I believe... ya just can't win!). 

Greg


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## chuck n (Jan 2, 2008)

Greg. 

Aluminum oxide is a safer label. They both are hard, and work very well as an abrasive.

Sand papers contain many different materials. Some are harder, more abrasive than others. There are two things that help sand paper: the hardness of the abrasive and the adhesive that holds the sand to the paper.

Chuck


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## Greg Elmassian (Jan 3, 2008)

I should be able to remember corundum, since I (supposedly) learned the Mohs scale of hardness in elementary school... oh well... just keep correcting me until I get it right! 


Greg


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## gaugeonebloke (Aug 18, 2008)

Where's a tribologist when I need one! 

Very helpful guys. I found this link with friction co-efficients. 

This table may be for the metal in it's pure state rather than for the oxides, it does not say. 
http://www.engineeringtoolbox.com/friction-coefficients-d_778.html 

Seems: 
1) Nickel - Steel is as good as Al - Steel; 
2) Steel - Steel would be best for friction(Cliff Barker sells stainless steel track but maybe SVRR flat bottom SS code 250 rail would better model hefty Appalachian rails); 
3) that brass track should be avoided and; 
4) forget about steel wheels on oily track. 

I don't think oil on track would be a huge issue because realistically the gradient is not going to experience the mileage of the continous loop. 

It has occured to me that if I boiler tested up to 10 or a chancey 12 atmospheres ( 5 to 6 atm running), that would boost the stock of steam power. Of course the loco would still need the firebox heat throughput to support than capacity.


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## Greg Elmassian (Jan 3, 2008)

Yes, the oxide has a very different coefficient of friction... 

Stainless steel is VERY slippery, the worst choice for you.. 

Oxidized brass is not bad, would make it a second to oxidized aluminum 

Nickel silver should not be confused with nickel plating... nickel plating as slippery as SS. 

Not a lot of experience with NS rail and steam/battery... 

Greg


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## Ehilsan (Mar 28, 2014)

Well i want to say you that this is one of the challenges of live vapor. On full-sized engines there is a top piece on the flame box and h2o encompasses the flame box on the sides and top. If the level gets low enough that the top piece is not covered it heats up rapidly. If h2o then comes back over the top it flashes into vapor and often causes an explosion.


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## SD90WLMT (Feb 16, 2010)

If'n ya can't redesign that steep grade away..building a much longer snakier run..twice as long..

Probably ought to consider a climbing rack run...no slipping here!!

Or ...realistic approach..
Build a incline... drop the cars at the bottom and cable pull to the upper level..then complete the journey with a loco on level ground...

You have steam volume and pressure to contend with...
Throttle control to manage..
Working this hard uphill will consume fuel at a higher rate...
Then there really is a slippage problem.. 
I have not run sparkies over a 3.0 % grade...Greg does climb steeper, but shorter climbs...still with track powered sparkies...

Try to have fun...just seems like your pushing the practicle limits here....it is a toy!!!

Dirk


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