"N" Scale Grade


My F45 is coming from ModelTrainStuff.com. But it's pretty easy to find all over. As for losing pickups from the Bullfrog Snot: I have to sacrifice something. If it works, that will be a pretty small price. I wouldn't be concerned if I had 6 axles, but I'll just have to try it out and see what happens. The good news it it can be easily removed. And there is a tip to clean it off of the wheel flanges on the treated wheels so you can still get at least some pick up through the flanges (not the best, I know, but better than nothing).
 
Most grades in N scale should be limited to 2% or less for optimum performance of most locomotives. You must also take into consideration if the grade involved curved radii. This will affect the locomotives performance.

4% grades should be avoided if possible when designing a new layout. The grade I'm using on the "new" JJJ&E is 1 1/2%.

On the "original" JJJ&E which was in operation over nine years, the entire mainline was graded (2%). It was giant "nolix"
 
Re: the pull meter, I hope nobody has bought one yet! It just arrived this morning and I'm disappointed. Two things-

Q. Does it work?
A. Absolutely! The range is great and it's very accurate with predictable results every time. It can also measure pushing forces in addition to pulling ones, although not rated as highly (6kg as opposed to 10kg for pulling).

Q. Does it work for N scale?
A. No. :( The kilogram reading goes up in increments of 0.005kg, or 5g, which is really not a lot. My SD24 got a reading of 0.010kg. One of my F7s got a reading of 0.015kg. One of my F45s got a reading of 0.025kg. The problem is not the accuracy of the device (all three F45s together pulled 0.075kg as expected), it's that even increments of 0.005kg, tiny as that amount is, are just too big to get a meaningful read out for such small trains. When I first saw the readings I thought I was doing something wrong, because surely the 29 cars that one F45 can pull weigh more than 25g! Of course they do, but that weight is going onto the tracks, the trains aren't actually pulling it. This is why just one or two bad rollers throws a spanner in the works.


I will be selling this off to someone who can use it, such as a HO modeller. I'm also going to write Micro-Mark and suggest that they add note advising of the inadequate performance for anything lower than HO.
 
Thanks for the review Pete. That is what I kind of expected.

Did you do any measuring of what force it takes to pull a long string of cars?
I'll guess that a single well rolling car on level track would take much less than 1gm.

Some physics: The force to pull a car is equal to the cars weight times the coefficient of the rolling friction plus any drag from bad parts (F = k*w + d), the coefficient can be as low as 0.001. So the force to pull a car can be very small.
 
I Blu-Tacked the pull meter onto a flatcar behind the loco and then coupled the drawbar to the rest of the train, which was 28 cars. It was reading 0.010kg on a flat area through a corner, and went to 0.020kg on a grade where my F45 started to struggle. If it was accurate to a 4th decimal place it would be amazing for N scale.
 
Yesterday I fixed one of the terrible rollers, improved the other one (MT trucks were too short), and vastly improved some others that were ok but not great. I also replaced the couplers on some other cars, taking my freight consist up to 29 cars. I retested the F45 on the grade and it got all the way to the top, although it was starting to struggle a bit.
So I finally got those WS risers today and have set up a more permanent test track that utilizes them. At one section the track climbs up a moderately-curved 2% grade until it crosses over itself and then heads back down. I decided to see exactly how much of an effect the curve would have on pulling ability by retesting the train from above on the new setup.

[YOUTUBE]wTTxCH_ziag[/YOUTUBE]

I have to admit I didn't expect that result! I'll need to get some more at some point so I can make a helix and test that my layout is actually feasible.

Got your F45 yet, SilverBlade? If so, thoughts?
 
I do have my F45 and I've been busily putting her through her paces. She definately pulls better than my Dash 8, I still am not getting the same performance you did. I only have 20 cars right now (all of them good rollers since I went to task with a fist full of new trucks for everything that needed it) and I can climb at 3% with them, but not at a modest speed. I have to juice it up to an unrealistic scale speed to run smoothly. And it's picking up a vibration that doest sound very seemly.

I've redesigned my track plan to allow for a 2% grade all the way up and both F45 and Dash 8 are doing better. I've built a new test RR and will post results in a few days.
 
Is the 3% curved at all? If so I wouldn't be surprised if it was struggling with 20 cars given the dip in performance I've seen when curves were added. More testing will be needed but I'm thinking I may even need to alter my layout design slightly to have a tougher grade on the straight sections and a milder one in the helices.

You could spend a lifetime trying to work out an exact formula for what a loco can pull up any given grade & curve radius combination, but I think what I've tested so far gives me at least the name of the suburb that the ballpark is located in. If one F45 gives out with 29 cars on a 2% grade, then I think it's a fair assumption that-

-the same lone F45 would reach its limit with 14.5 cars on a 4% grade, or
-29 cars on a 4% grade if you used two F45s (assuming same curve radius, in my video it is 16" at the tightest point).

My current layout plan peaks at a 3.5% grade on the eastern helix that incorporates 11" radius curves (in short 180° segments). If the above assumptions are at least mildly accurate then the grade alone should be doable with two F45s + 29 cars, but I can't put a figure on what effect the tighter radius will have so who knows if the lower grade balances out the tighter curves.

Another thing to consider is exactly what constitutes satisfactory performance. Given the above video findings I could probably take the consist down to 25 cars and have the train clear the grade, but it would likely be grinding the rails pretty heavily towards the top. I don't mind a little bit of wheelspin (it's probably unavoidable), but if the train is noticably slowing down then I wouldn't be happy (I'm using TCS decoders with really good BEMF so resistance from gravity is mostly compensated for).

Given everything above I think that all three F45s could pull 29 cars up my 3.5% grade, but I'm not 100% confident they could do it without grinding the rails. On a positive note, my layout has a long bridge (split into two sections) that runs along the back of the layout between the two helices with the grades starting at either side. If I move the start of the eastern helix downhill grade to the middle of the bridge, the grade goes down to 3% (the western helix is already at 3.1%).

Lots of experimentation to do once I get a proper baseboard happening!
 
Given the above video findings I could probably take the consist down to 25 cars and have the train clear the grade, but it would likely be grinding the rails pretty heavily towards the top.
Nothing better to do so decided to follow up on this. :)

-24 cars was doable, but the train was moving very slowly at the top.
-22 cars faired better, and this trend continued to get better as I removed cars.
-With 17 cars the grade was cleared with a loss of speed so small that I had to measure it to be sure it was there. On level ground it took 1.6sec for the F45 to pass a single point, near the top of the grade it took 1.9sec. Very tolerable.
 
My grade has to be on a curve. In fact, on my perminate layout, it will be mostly curved. No other way. I tried doing the steep straights, and shallower curves but not with a lot of success.
...here's my plan: Hit a steep 4% grade on the low end and taper it down quickly with the longest stretch of the run at 2% and just enough transition at the top to keep from uncoupling. I've got 80" to work with so it'll look like this:
Run Grade
12" 4%
20" 3%
38" 2% (leading into an 11" rad curve)
10" 1%
One thing I have noticed: Positioning heavier cars in the front of the consist has helped very noticably. If you can get the heavier cars "over the hump" so to speak, before you take on the weight of entire train you pull less weight at any given time. Whether this is something you can take advantage of or not depends on each situation, but it's worth experimenting with.
 
That's not a bad idea at all, provided the grade is has the hump like yours does. On mine I don't think it would make a difference as the entire train is on the grade by the time it reaches the top.
 
Here is a comparison of my Dash 8 and F45 and a demo of Bullfrog Snot. The results were pretty dramatic.

[YOUTUBE]5ALOtStomBA&context=C357df0dADOEgsToPDskIKhVvjtZqAXfhtuCuKjSfp[/YOUTUBE]

I did notice some loss of electrical pick up on my Dash 8 after I applied the Bullfrog Snot. I'm experimenting now with different configurations (front trucks vs rear trucks, alternating wheels, etc). The loss of pick up is not severe and I'm confident I can get a good comprimise dialed in.
 
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Haha, love the extra car at the end. Not a bad improvement at all. Do the instructions give any indication of how long the stuff lasts for? I would imagine that eventually it's going to wear down and need reapplication, especially when the layout involves grades where at least some wheelslip is inevitable.
 
There isn't any indication on the product but yes, it will eventually wear out. The cured snot is softer and thinner than a conventional rubber traction tire. If you can figure out how to get the wheels to turn very slow and steady (scale walking speed), it's easy to remove and comes off clean.
 
videobruce: he applied the *snot by turning the loco on its back and applying low voltage to the other truck. This turns the wheels 'naturally' so a brush can be held in position and the *snot applies on its own. It also generates a nice smooth application so the engine doesn't bounce around on bumpy boogers ;)

Looks really effective. How visible is it when the loco is on the rails?
 
Here is the best video on how to apply:

[YOUTUBE]nOawcCRpxmo&feature=BFp&list=FLc46c5yjDytRxK2mzAi5uMg[/YOUTUBE]

As for how long will it last: Heck I donno. As T.J.O. eluded to earlier, how much your wheels spin is going to obviously be a determining factor. In any event, I would expect it to last quite a while, just not for ever and ever.

To answer how it looks on the track: Here is a close up pic of the cured treatment. My best results have come from treating the front truck on alternating axiles. You have to inspect the wheels closely to see it, and on the layout it will be completely unnoticable.

BullfrogSnot.jpg



But one cautionary note. Curves are still the real grade killer. you'll notice from my video that the train did slow down at the top of the curve. BF Snot certainly helped (a lot), but it has it's limits. My advice is experiment. Can't go wrong with experimenting. And as I said earlier, it's not hard to remove.
 
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