anyone know how many strait tracks and how many curves are needed to make a figure 8.does the length of the track matter.
thank you in advance
jerry p
the length of the track does matter alot. if you use the 14 piece pier set, with one pier per section of track, it appears your grade will be around 5 1/2 to 6 %. that is far too steep to be recommended practice. you can either use the first 12 piers of the 18 piece set, one per section, or space your 14 piece piers out to about 1 1/2 sections apart to lessen the grade to something your locomotives will be able to pull a full train on.
there are many different possible configurations of a figure 8, the smallest of which requires 22 18r curves and 2 9" straights.
I had the same problem Jeff indicates with the slope being unmanageable. When installing the piers as Bachmann recommends, with a Pier supporting every track joint, it was STEEP!.
Someone recommended I purchase 2 sets and use one pier with the base and the same pier from the other set without the base or shim them to get about a 3% slope. I instead scrapped the idea of using the Pier set.
this might be getting away from the subject a little, but here are some quick estimates of how steep your grades are.
grades are usually expressed as a percentage of height to run. 1% rises 1" per every 100" of run. this can be rounded off to one inch rise per 8 feet (96") forward, and reduced to 1/4" per 2 feet. if you are building your grades from plywood this 2 foot is the length of a standard level. each additional percentage equals another 1/4" of rise. you can buya piece of 1/4" mounding, cut off several pieces, and stack them in stairstep fashion to make a simple grade guage. when setting the grade, work from the bottom, place the stairstep at the bottom, set the level on the appropriate percentage and raise the wood until the level is level. fasten the wood, then more 2 feet further up the grade.
when using pier sets the percentages are the same but the calculations are a little different. the standard section of track is a 9" straight. 18r and 22r curves are also about 9 inches in length. 11 of them make 99" rounded to 100. for our purposes, we add another section to make 12 or 108". this is important because you need about 3" of verticle clearance for one track to pass over another. 12 is divisible by 3, reduced to 4 sections of track per inch rise. thus if your track gains height at a rate of 1/4" per section, you have slightly less than a 3% grade. for this reason, most trestle sets have 12 piers, in 1/4" incerments.
bachmann's sets appear to be different. the 14 piece set apepars to have piers in 1/2" increments, far too steep for our purposes. the 18 piece set appears to have the common 1/4" increments, but added heights up to 4 1/2" to clear the much larger On30 equipment. thus my recommendation to only use the shortest 12 piers of an 18 pier set, which keeps the grade down to about 3%.
for the record, i have grades of 4% on my layout. that is the upper limit of what i recommend. tests by others have shown any given locomotive pulls less on the upgrade than on level. the steeper the grade, the worse the pulling power. for a 4% grade you are down about 1/6 the pulling power you'd expect on level track.
hope this helps.
Quote from: jward on October 25, 2012, 01:02:56 PM
for the record, i have grades of 4% on my layout. that is the upper limit of what i recommend. tests by others have shown any given locomotive pulls less on the upgrade than on level. the steeper the grade, the worse the pulling power. for a 4% grade you are down about 1/6 the pulling power you'd expect on level track.
FWIW. ...
Last week I fulfilled a goal to ride the Cumbres & Toltec. The guide on the train said the ruling grade from Chama, NM, up the hill to the top of Cumbres Pass is 4%, and that a 4% grade is about the upper limit for a steam locomotive. Our train had seven cars; the guide said more than seven, or maybe it was eight, they need to double-head.
About 26 years ago, my wife & I rode the Cog Railroad to the top of Mt. Washington, NH. That was a trip!
It is the second steepest rack railway in the world with an average grade of over 25% and a maximum grade of 37.41%. The railway is approximately 3 miles long and ascends Mt. Washington's western slope beginning at an elevation of approximately 2,700 feet above sea level and ending just short of the mountain's summit peak of 6,288 feet. The train ascends the mountain at 2.8 miles per hour and descends at 4.6 mph. It takes approximately 65 minutes to ascend and return.
Now they have 2 steam engines and 4 biodiesels making the trip. If you ever get there, you have to do this.
the key to their ability to run on tracks that steep is the rack of teeth betwwen the rails. there is a gear under the locomotive which engages these teeth and pulls the locomotive along. a regular locomotive would not be able to pull itself up such a grade.
as for the cumbres & toltec, 7 cars on a 4% grade sounds pretty good to me.
You are correct, and you can really feel it every time the gears engage to pull. Vibrates your teeth out. They had pictures of one train where the gear broke and the train went into freefall down the track. It was not pretty or even recognizable. The trip back down was just as jarring.
as a kid, my dad often took me to blackwater canyon in west virginia. the western maryland railway had a 3% grade through the canyon, and curves were so sharp they were restricted to smaller diesels like f7s, rs3s and gp9s (the wm gp7s didn't have dynamic brake so they tried not to use them on this mountain).....as i recall, these locomotives were rated at 5 loaded hopper cars up the grade. trains often needed up to 12 engines to make the grade. my bachmann gp7 and gp9 pull a little more than that on my grade, but not much more. it was an experience to stand on the canyon rim and watch them grind their way up hill.
Quote from: jerry p on October 24, 2012, 08:34:04 PM
anyone know how many strait tracks and how many curves are needed to make a figure 8.does the length of the track matter.
thank you in advance
jerry p
jerry-
You might look into Woodland Scenics styofoam ramp subroadbed to support your tracks if you can conceal the supports rather than have
bare rails on flying, unsupported crossties. These are wedge-shaped blocks which are cut partially through from side to side, with the cuts
alternating. This allows you to add whatever curvature you want/need as well as control the grade by stretching or compressing the
subroadbed.
-- D
Jerry,
Here is a link to the supports --D is reffering to. There are a few good films on the page as well you can run.
http://woodlandscenics.woodlandscenics.com/show/Item/ST1416/page/1 (http://woodlandscenics.woodlandscenics.com/show/Item/ST1416/page/1)
Jeffery,
Funny how you recall things from when you were really young. I remember an Aunt and Uncle of mine who had a summer cottage in West Monterrey, Pennsylvania on the Allegheny River, way north of Pittsburgh. Up there, the Allegheny River is only about 100 feet across! There was a train track right in front of the cottage, between the cottage and the river.
We use to put pennies on the rails and were amazed at how flat the train made them.
Looking at that area on Google Maps now shows the railroad is no longer there, but you can just make out where it was.
Silly now, but awsome back then!
Quote from: jward on October 25, 2012, 11:09:53 PM
as a kid, my dad often took me to blackwater canyon in west virginia. the western maryland railway had a 3% grade through the canyon, and curves were so sharp they were restricted to smaller diesels like f7s, rs3s and gp9s (the wm gp7s didn't have dynamic brake so they tried not to use them on this mountain).....as i recall, these locomotives were rated at 5 loaded hopper cars up the grade. trains often needed up to 12 engines to make the grade. my bachmann gp7 and gp9 pull a little more than that on my grade, but not much more. it was an experience to stand on the canyon rim and watch them grind their way up hill.
My buddy and I were so amazed at the sharpness of some of the curves on the Cumbres & Toltec that we actually inspected some of the locomotives to see whether any of the drivers were "blind." It seemed pretty amazing to us that a Mikado--even a narrow gauge one--could make some of those curves.
Hmm. I wonder if the original poster is still out there?
If I were to indirectly answer his question, I would say "Download and learn to use Anyrail.com,
which is a fun and easy to learn CAD program for designing model railroad layouts."
More directly,
"Anyone know how many straight tracks and how many curves are needed to make a figure 8?"
Given the length and width of your table top and the radius of your curves, it can be calculated using geometry, or laid out on a CAD program.
(Table top width restricts the radius of the curves you can use, i.e. you don't want your track circle hanging over the edge of the table.)
"Does the length of the track matter?"
Yes.
Hope this helps.
Sincerely,
Joe Satnik
Quote from: jerry p on October 24, 2012, 08:34:04 PM
anyone know how many strait tracks and how many curves are needed to make a figure 8.does the length of the track matter.
thank you in advance
jerry p
For an 'Up & Over" using 9in straights and 18in radius curves it takes 8 straights and 18 curves to make a figure-8.
I also figured the 14 piece pier sets were for getting level track across a valley/gulley, not for doing up & over.
Len
Len,
I never thought of using it for that, but you have maybe helped save me a lot of work on my Christmas layout, as I have 2 streams to landscape down to, across and back up. This may work out great by cutting the large bases down in size, gluing them to the layout and attaching the piers to the permanently installed bases. When it comes time to put it all in storage, just remove the piers from the bases and pack it all up. Much easier than using the trestle I had planned on. Tonight I'll pull the box out and try it.
Thankx!
Dear All,
In the up and over figure 8 example of 18 (18" radius - 30 degree) curves and 8 (9")straights,
you would use 4 straights above and 4 straights below.
Assuming you would use each pier at the gap between 2 track pieces,
an even number of straights (above) would put a pier right on top the track below it.
The E-Z Track 36" bulk straight could be substituted for four 9" straights,
but you would have to put vertical bends in it. (Heat gun?)
Another alternative, an 18" long homemade girder bridge built to accommodate either E-Z Track or other Code 100 non-roadbed track.
Hope this helps.
Sincerely,
Joe Satnik
In the words of an old, but very respected Greek philospher ........ Bummer!
Joe,
There doesn't have to be a pier right on the center joint of the upper track. Putting a pier to either side of the lower track works just find.
Len