After many years, I am getting back into model railroading. As I design a new layout, which will include a large oval helix, I need to understand the pros and cons of installing switches on a grade. In my case, the initial installation will include a double crossover in ho scale using Atlas switches. The grade is 2%. Appreciate any constructive info.
[#welcome] to the forum. Your initial posts are delayed and this one appear back in Saturday’s posts and may have been overlooked.
RRMel has constructed a double crossover out of Atlas turnouts, http://melvineperry.blogspot.com/2012/06/june-25-2012-my-double-crossover.html
I may be wrong and if so, we will soon find out, but turnouts at a change of grade are a problem, a constant grade with a turnout in the middle is not a problem.
You basically cannot place a pre-manufactured turnout on a grade change.
On a grade is fine, just don’t change the grade under the turnout.
Model grade changes are severe because of the scale compression.
The problem is one of distortion. The distortion of a turnout just leads to endless running problems.
The turnout needs to be laid on a flat surface. The surface can be sloped but the slope must be constant.
In practice the approaches to each track connected to the turnout should also be flat for as far as you can manage. My personal rule of thumb is the approaches to each leg of any turnout should be on exactiy the same slope as that of the turnout for as long as the wheelbase of the longest piece of equipment I expect to traverse that turnout. Conservative, yes, but also reliable.
Flat but not necessarily horizontally level.
[#welcome]
I totally agree, I learned the hard way putting a turnout near a grade transition I tried all kinds fixes for years to make it work and ended up moving the turnout 18” to prevent derailing.
My layout is HO scale and the turnout is a code 100 Atlas Custom Line #6L, it was originally placed at the bottom of a 3½% grade leading into my yard. I tried several code 100 turnouts both Atlas and Peco, no difference.
To make things worse the track was hidden making it harder to access. After moving the turnout and adjusting the scenery around the turnout everything works great, not a single derail since the move.
I will say this, the Proto 2K locomotives were the worst at derailing. After couple of attempts to fix the problem my non Proto locomotives would clear the repaired turnout but every Proto locomotive would still derail when the turnout was set to divert from straight through.
I sold off many of my Proto diesels only keeping a couple of SDs & GPs, all the Fs and Es went to eBay. Even though the Protos clear the moved turnout easily I rarely run them. I guess it just left me with a bad taste of Proto, all my Athearns cleared the turnout after the first attempt at a fix. My Rivarossi Cab Forwards cleared the turnout after couple of fixes.
Mel
My Model Railroad
http://melvineperry.blogspot.com/
Bakersfield, California
I’m beginning to realize that aging is not for wimps.
Switches are a source for derailments without a grade change, so why increase the chance of them happening?
Hello All,
[#welcome]
What is the purpose of the double crossover?
This is a complex track arrangement that has perplexed many a savvy model railroader even on level ground.
Not knowing your particular track plan, is there a way you could put this on a plateau with grades emanating from each leg with easements?
On my pike, I had an “S” curve diverging from the mainline to a 22-inch radius curve with a 3% grade.
This track arrangement caused nothing but derailments, shorts, and headaches.
I reworked the track plan and moved the turnout off the mainline to a siding thus eliminating the “S” curve and added a 9-inch easement on the diverging leg to the 3% grade.
Now the GP30 locomotives and 34-foot hoppers negotiate this section with no problems. (See my disclaimer/signature.)
The saying goes, “There is a ‘prototype’ for every situation.”
I’m sure that railroads have been forced to put crossovers on grades but this practice would be avoided if an alternate can be found.
Unfortunately, as modelers, we don’t have the luxury of space and we sometimes must make compromises and compress features.
Is there a way to re-work your track plan to eliminate the need for a double crossover?
As always- -a track plan diagram would be helpful.
Hope this helps.
“No grade change near a turnout” is one of the great myths of model railroading.
I put grade changes under almost all turnouts that leave the mainline for a siding and have no problems at all - even with a ten-coupled locomotive. The prototype does the same thing. The grade change simply has to be gentle enough that the rigid wheelbase equipment doesn’t lift the wheels enough for the flanges to lift clear of the rail head.
So how gentle is gentle? Two vertical curves in bout 16 inches, lowering the siding by about 1/8 inch. That’s how gentle. I’ve never had a derailment caused by the trackwork.
I would use the longest/highest number turnout I can find. Coming down your 2% grade, you may have a lot of cars/weight pushing on the rear of the train and when the engines cross over and the cars start to cross over, with that pushing weight, small wheel flanges, light cars on the head end, heavy cars on the tail end, something bad may happen. This is if I see your helix as a continuous 2% grade with no level track sections.
Is there any chance to have two single cross overs in close proximity of each other, that way you eliminate the diamond of the double cross over.
No grade change under a turnout is the “great myth” and it isn’t a myth.
How close you can go to the turnout with the grade commencement depends on the train speeds over the grade change, not unique to turnouts actually.
1/8" in 16" is 1/128 or about 0.75% grade. How long is the actual grade transition on your siding?
Try 2% and see if it’s a myth.
The OP is asking about the whole turnout section plus connecting tracks being located on a 2% grade.
That works except for the downhill momentum problem which is very real.
Traversing the turnout downhill located on a 2% grade can result in fairly spectacular derailments especially at mainline speeds. When we had such a derailment over a 120 degree crossing located at least one locomotive length from the end of a 2-3% grade my layout partner described it as prototypical. Fortunately, no damage resulted. Prototypically, it would have hit the newspapers.
Turnouts and crossings include relatively big gaps in the rails at the frogs and model railroad turnouts include quite sharp transitions from tangent to curves. They work best on level grades.
We use Peco #8 turnouts for our crossover at the end of our 2-3% grades and
[#welcome] to the Model Railroader Magazine forums. Please stick it out through the moderation delay in your posts. This will end pretty soon, and we would love to have you.
I only installed a turnout on a grade on one layout, and it was not my layout. It was a disaster. We checked all parts of the turnout with the NMRA gauge, and could find no problem, but lots of derailments happened at the frog.
After that experience, I have avoided turnouts on grades. I enjoy flawless operation, so I will not be attempting this again.
A complicated piece of trackwork, like a double crossover, would only increase the probablility of a problem. Why tempt fate?
I hope this helps. I also hope to hear from you more in the future.
-Kevin
There are two different things being talked about here.
One is turnouts on a grade, and the other is grade changes under a turnout. I was talking about the latter. You’re talking about the former.
Grade changes under a turnout are just fine, as I’ve proved on several layouts.
Turnouts on a grade deal with an almost totally different dynamics.
There are two different situations.
If you try to put a grade change under a turnout some portion of that turnout will not be supported by roadbed and will distort.
That’s often true. In my case, where one end of the turnout is lower than the other end, the tracks at either end tend to pull the turnout down onto the ramp (the ramp is very gentle). Sometimes I need to add spikes at a couple points along the turnout to make it set down on the ramp, since the ramp is actually two vertical curves spaced about six inches apart. But the vertical curves are so slight that I don’t usually need to add the extra fasteners.
Here’s what I’m talking about. In yards or multi-track sidings, the first turnout off the main is laid directly on a ramp. The ramp is about 16 inces long and takes the track fron the 1/4" mainline roadbed cork to the 1/8" roadbed cork.
The turnouts on those ramps have worked reliably for years, allowing even my longest-wheelbase locomotive (a 2-10-2) to navigate them without issue.
In the case of a single siding the ramp is just past the turnout. Even though the vertical curve is right off the end of the turnout, it’s shallow enough that it causes no problems, and it looks very prototypical!
