Track Spacing and Fast Track Crossovers


F

fcwilt

Active Member
Hi,

As you may know Fast Track HO Crossovers (and others) are designed for 2" center-to-center track spacing.

This sort of dictates that straight track will be on 2" centers.

The NMRA recommendations for spacing on curved track of 32" radius is 2-1/2" for Class Ia equipment (think "Big Boy" locos).

So since I wanted a minimum radius of 30" the NMRA recommendations would make the outer radius 32-1/2".

So far so good.

My question is: How to transition from the 2-1/2" spacing on curved tracks to the 2" spacing on straight tracks?
 
I don't know much about Fast Track, but the way it is done with other types of trackage is not to use a one-piece crossover, but use two turnouts with a spacer of straight track between the two turnouts that gives the correct spacing.
 
fcwilt said:
Hi,

As you may know Fast Track HO Crossovers (and others) are designed for 2" center-to-center track spacing.

This sort of dictates that straight track will be on 2" centers.

The NMRA recommendations for spacing on curved track of 32" radius is 2-1/2" for Class Ia equipment (think "Big Boy" locos).

So since I wanted a minimum radius of 30" the NMRA recommendations would make the outer radius 32-1/2".

So far so good.

My question is: How to transition from the 2-1/2" spacing on curved tracks to the 2" spacing on straight tracks?
Click to expand...

You may want to go even bigger on the outside, I can tell you that 2 big boys, going opposite directions will hit each other with the inside radius being 34 and the outside 37.:eek: Ive seen it!
Schnauble cars need even more real estate!!!:eek:
 
kbkchooch said:
You may want to go even bigger on the outside, I can tell you that 2 big boys, going opposite directions will hit each other with the inside radius being 34 and the outside 37.:eek: Ive seen it!
Schnauble cars need even more real estate!!!:eek:
Click to expand...

Well that's discouraging - I was assuming the NMRA documents were correct.
 
fcwilt said:
Well that's discouraging - I was assuming the NMRA documents were correct.
Click to expand...

The engines didnt hit real hard, just kinda slapped each other.

Remember, big articulated equipment is out of the "norm" , like the real railroads, when they came on the scene, we too have to make adjustments.
 
For my recent helix build, I didn't want unwelcome forays, sliding on my back and pulling myself on the smooth floor under the mountain, to fix problems that never should have been allowed in the first place. So, I was careful to do some trials with track separation on the curves that I was using for the twinned route up and down the helical plywood path. My worst overhanger is the Rivarossi H-8 2-6-6-6. If anything caught close hardened ground goop on my last layout, it was the cab overhang on that loco. So, it and a Walther's heavyweight passenger car on the other track were my test buddies. I eventually found that 3.5" was fully safe, and this was placing both items alternately on both tracks to see what difference it made. This was for an inner curvature of 33" radius and an outer of 36" radius, give or take the normal variance that people impart to their curves when laying flex track.

You may get away with less, or you may need more. My message is...FIND OUT!
 
kbkchooch said:
The engines didnt hit real hard, just kinda slapped each other.

Remember, big articulated equipment is out of the "norm" , like the real railroads, when they came on the scene, we too have to make adjustments.
Click to expand...

Understood but the NMRA documents lists different classes of gear and they say this in regards to class Ia:

"Includes the largest steam locomotives with four-wheel trailing trucks, articulated locomotives, those with rigid wheelbases in excess of 20 feet, full length passenger cars and other long rolling stock"

Well it's too late to make drastic changes now - I will just have to adjust the schedules to avoid conflicts.
 
Center distance spacing on curves is relative to the radius. The tighter the radius the more overhang. Passenger cars and other long rolling stock will overhang at their centers to the inside of the curve. Articulated locos will overhang at the smokebox and cab to the outside of the curve. With that in mind it follows that there will be spacing difference for different track radius dimensions, more for tighter curves than for broader ones.

Crandell's idea is good. Temporarily tack down some flex track to a piece of plywood at the two radius you intend to use and move a couple of cars and engines by hand back and forth on both pieces to check for clearance. Once all is well note the radius of each piece and the center distance and transfer them to the layout.
 
fcwilt said:
Understood but the NMRA documents lists different classes of gear and they say this in regards to class Ia:

"Includes the largest steam locomotives with four-wheel trailing trucks, articulated locomotives, those with rigid wheelbases in excess of 20 feet, full length passenger cars and other long rolling stock"

Well it's too late to make drastic changes now - I will just have to adjust the schedules to avoid conflicts.
Click to expand...

The NMRA standards are guidelines, but not the law. Manufacturers still are strapped to the almighty bottom line, so if that demands fudging a measurement here, or changing a truck pivot there, they are going to do it. Read the product reviews in the NMRA Magazine (formerly Scale Rails). I amazed that once in a while, a conformance warrant gets issued.:eek:

Back to the issue at hand, I suspect you may only need less that 1/4 inch here or there to make it work, just a little wiggle really, that should be attainable!:D
 
C'mon! I have my whole layout designed with 2 1/2" spacing! If I have to make it 3 1/2" for my big boy's or my H8 to run I will be very bummed. The next day off it looks like I have some testing to do...:(
 
irocinblue89 said:
C'mon! I have my whole layout designed with 2 1/2" spacing! If I have to make it 3 1/2" for my big boy's or my H8 to run I will be very bummed. The next day off it looks like I have some testing to do...:(
Click to expand...

Not nearly as bummed as you would be if you built it on 2 1/2 inch centers and 2 engines hit each other!!:eek:

What was that,,measure twice, cut once?:rolleyes:
 
fcwilt said:
Then I am a victim of my own ignorance - I thought the standards were also for modelers as to how they should build their layouts.

You live and learn.
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One has to read the NMRA documents to see what they really are. Some are just definitions, others are Recommended Practices, others like the DCC protocals are true standards otherwise it wouldn't work.

Where are all these old threads coming from recently?
 
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