2-10-2 and vertical easement


ctclibby

ctclibby

Well-Known Member
So working with my helix my 1st thought was to bend a piece of plywood to match the helix grade from tangent. Got to thinking about it and decided to delve deeper into it for the 'how long is the approach' question, JIC. I have big steam that needs to go up/down the helix; 4-8-8-4, 4-6-6-4, 2-6-6-2, 2-10-0 and 2-10-2. The 2-10-2 is the beast I need to play with as the others all pivot AND the drive wheels move up/down bout 3/16" at the axel bearing holder except for the wheel/motor connection. The 2-10-2 looks to be more rigid with maybe 1/16" up/down movement. I am unclear if it is a heavy or light 2-10-2. Depending, the 1st driver to the 5th driver is 21' or 27', so in order to keep all the drivers on the track as much as possible the transition spiral is what I am wondering about. From where I sit right now, that spiral has to change a rate of at most 1/16th every 27 feet ( assuming heavy ). What is the general consensus for this - should I guesstimate 30' ( ~4 1/8" )...every 4 1/8" we change by 1/16th" or a 1.5% grade?

The helix entry/exit benchwork approach right now is about 30" actual, the grade start up/down is 3/4" above/below the tangent tracks and the grade I need to meet is 1.96%. So looks like I would need ( 3/4")/(1/16") * 4.125" or about 50" for the spiral. That seems large to me. Or should I keep with 1/16th every ~27ft ( ~3.75" ) or about 44".

Boy, that made my brain hurt!

The idea here is to maxamise what I can pull up the thing.

Anyway, making the approaches a bit longer is not a big deal as I do have space for that. As to keeping stuff coupled, that should not be a problem as the 1/16 change is about 1/3 of the coupler nuckle height on the front, with the cow catcher height above the rail at .208" and the trip pin to the ties is about .107". All the tender wheels move up/down more than the engine. Oh, and the others being articulated allow movement up/down between driver sets so maybe a 'non issue'. Also, the passenger cars wheelsets move up/down quite a bit although the diaphrams could look like sh.t.

This begs the next question: Armstrong uses 32/R to calc the effective grade. The 2 down tracks are not a problem, run through and up tracks could be. The 32/R: is that for a full circle, part of circle or what? There is not any data that I can find about this. The first track curve hit in the helix is less than a 90 degree arc then a tangent section. It seems to me that less than 1/4 circle would be less of an effective grade than 1/2, 3/4 or full circle. What gives here?

If you have made it down to here, good job! Now your brain hurts.

Thoughts or ideas?

Later
 
santafewillie said:
Just use diesels! o_O Problem solved.;)
Click to expand...
When you connect your 2 levels, you will get to play with this too. With diesels you have body mounted couplers so you still need a 'transition' to get from flat to the helix grade. The distance from the inside drive wheel ( front and back ) to the coupler is less, so just bending something to fit will probably get you started.

Later
 
When I had my helix I just mounted it +/- 1/4“ from the level, laid track into, then shimmed to follow the natural transition. Of course I didn’t run big steam but I never had any issues with long cars or the schnabel.
 
You stated that your most rigid locomotive has a 1/16 inch up and down play in the drivers. That tells me that if you turned your easement into a circle then your minimum circumference could not exceed 1/16 of an inch in circumference
 
ctclibby said:
So working with my helix my 1st thought was to bend a piece of plywood to match the helix grade from tangent. Got to thinking about it and decided to delve deeper into it for the 'how long is the approach' question, JIC. I have big steam that needs to go up/down the helix; 4-8-8-4, 4-6-6-4, 2-6-6-2, 2-10-0 and 2-10-2. The 2-10-2 is the beast I need to play with as the others all pivot AND the drive wheels move up/down bout 3/16" at the axel bearing holder except for the wheel/motor connection. The 2-10-2 looks to be more rigid with maybe 1/16" up/down movement. I am unclear if it is a heavy or light 2-10-2. Depending, the 1st driver to the 5th driver is 21' or 27', so in order to keep all the drivers on the track as much as possible the transition spiral is what I am wondering about. From where I sit right now, that spiral has to change a rate of at most 1/16th every 27 feet ( assuming heavy ). What is the general consensus for this - should I guesstimate 30' ( ~4 1/8" )...every 4 1/8" we change by 1/16th" or a 1.5% grade?

The helix entry/exit benchwork approach right now is about 30" actual, the grade start up/down is 3/4" above/below the tangent tracks and the grade I need to meet is 1.96%. So looks like I would need ( 3/4")/(1/16") * 4.125" or about 50" for the spiral. That seems large to me. Or should I keep with 1/16th every ~27ft ( ~3.75" ) or about 44".

Boy, that made my brain hurt!

The idea here is to maxamise what I can pull up the thing.

Anyway, making the approaches a bit longer is not a big deal as I do have space for that. As to keeping stuff coupled, that should not be a problem as the 1/16 change is about 1/3 of the coupler nuckle height on the front, with the cow catcher height above the rail at .208" and the trip pin to the ties is about .107". All the tender wheels move up/down more than the engine. Oh, and the others being articulated allow movement up/down between driver sets so maybe a 'non issue'. Also, the passenger cars wheelsets move up/down quite a bit although the diaphrams could look like sh.t.

This begs the next question: Armstrong uses 32/R to calc the effective grade. The 2 down tracks are not a problem, run through and up tracks could be. The 32/R: is that for a full circle, part of circle or what? There is not any data that I can find about this. The first track curve hit in the helix is less than a 90 degree arc then a tangent section. It seems to me that less than 1/4 circle would be less of an effective grade than 1/2, 3/4 or full circle. What gives here?

If you have made it down to here, good job! Now your brain hurts.

Thoughts or ideas?

Later
Click to expand...
That formula made my brain hurt.

To calculate my grades, I always convert to 100" length and then measure the increase in elevation,( would be 2" if you want the 2% grade). As far as the transition from the tangent to curve, I cut one track about 1" shorter than the other where the tangent meets the curve. That helps keep it linear, then add whatever you need to under the approach track to maintain that profile. I use a steel ruler on edge to confirm.

Dave LASM
 
Helix help, maybe.

Layout Design Journal (LDJ-14) has an informative 14-page section on helix design. Also Rich Kolm's "Trackwork...Doing it Right" a clinic from the 2006 PCR Convention addresses a grades transition approach and departure angles. The former is probably copyrighted, the latter available on-line search. These won't answer all the concerns with the 2-10-2 but may help.

I have a pair of 2-10-2s painted by the late Mel Horne that were used as helper locomotives on my former Southern Rwy layout. Marvelous locomotives to watch shoving on the back of a train but now regulated to a display case.
 
Just take thrice the length of the driver wheelbase on your longest base steamer to get from the onset grade (level, I assume...) to the eventual average grade on the helix. This works for a grade change totaling 2.2%. Once you get closer to 2.5%, you should add a wheelbase length for every percent increase in grade.
 
That made my brain smoke. I have a figure 8 where the height difference between lower track and upper track is above 5". But my curvature at the sharpest point might be 27" radius. So pretty wide even by modeling standards. Something to ponder, the most critical part will be at the top of the helix where the loop will be ending and the grade will become level; if that is on a curve, then your driver flanges might leave the rail and you will have derailments. Best is to experiment how each steamer is behaving. What works for one wheel arrangement, might not work on another.
 
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