Incline performance?

Incline performance?

Postby Marquette » Thu Apr 17, 2014 7:58 pm

If I'm calculating this right, an increase of 26' over 360' is 7.2%.

How well would the SW (or other locomotives) perform pushing a single hopper car up such a slope?

I've begun work on a coaling trestle and I need to achieve a 26' rise. Since the PRR standard plans I'm working off of don't specify a grade for the ramp, I'm looking at a D&RGW standard plan for a coaling trestle, which calls for a 6% grade, but I'd like to compress the slope as much as possible, because even if 7.2% will work, that's 360' of ramp over 23 bents at 12' spacing, a 60' flat area where the hopper car will discharge coal into the chute, and a 96' embankment to get from ground level up to the first bent of the slope (which is 6' high, so, to get from 0' to 6' elevation)... 360' + 60' + 96' = 51.6 inches, or 4.3 feet, or 1.3 metres...
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Re: Incline performance?

Postby gerhard_k » Thu Apr 17, 2014 10:27 pm

Marquette wrote:I've begun work on a coaling trestle and I need to achieve a 26' rise... I'd like to compress the slope as much as possible...

I know from your other posts that you're all about replicating the prototype, but you might consider cheating a bit on the height - after all, a freight car is ~10 feet high, so maybe 18 feet should still give the general impression and relieve your grade or track length requirements a bit. I know - blasphemy...
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Re: Incline performance?

Postby Marquette » Thu Apr 17, 2014 11:56 pm

Actually there are certain things where I'm more than willing to compromise some... this is one of those. Using the DL&W's coaling trestle at Scranton Yards as an example, that one is 1016' overall, which would still be over 8' long in TT! That one, though, calls for a 4% grade. I have a diagram of a Rio Grande installation that calls for a 6% grade over 488' total (embankment + ramp + level area where the funnels are). The Pennsy one I'm wanting to represent is I think longer than that (plus it has a curve in it, which will be interesting to figure out how to replicate, since the Pennsy standard drawing calls for three 10x16 stringers on each side under the rails), but I'm more than happy to make it shorter - I'd like to fit the engine shop/station area into a roughly 2' 4" x 8' area.

This trestle is for coaling up steam locomotives... it needs to be at a height where the funnel, when extended, will be in position to fill the tender from not too far above, but high enough to be clear of it. The DL&W trestle looks to be 40-some feet at the coal chutes... the first test-bent I made for the equivalent area is 33' tall not including the stringers and ties, which will make it a shade under 35' with them.

The one steam locomotive that I intend to build one day is a K4s. The 20' and 24' tenders for these are 13' tall at the higher part of the sides. That leaves 22' to the top of the trestle - that is, to the top of the coal chute. Both the chute's hopper and the extending funnel need to have a slope steep enough to allow coal to flow through it - this is where I'll be able to save some of that 5' difference between my structure and the DL&W one, since I won't actually be sending coal through the chutes! Still, it has to look plausible.

As for slope - the PRR coaling trestle in Cleveland had a *very* steep slope:

coal dock mahoming street cleveland.jpg


But that would look very out of place in the scene I want to model. I have a number of hard-copy photos in books and whatnot of the trestle I want to model, but I only have a few digitally:

xenia trestle.jpg
xenia trestle.jpg (10.16 KiB) Viewed 394 times


Here's an end view. It's hard to make anything out but I'm just familiar enough with the structure to make an educated guess, based on the height of the hopper car on top of the trestle in this view, that the trestle is about 3 hopper cars high; my test-bent is 2.5 hopper cars high.

Here's an aerial view of the scene, with the trestle circled in red:

Xrr10.jpg


So all that to say I'm not sure I can compress it any further than 4' long and still have it "look right" in the scene without it being like 6 or 7 feet long. At the latter lengths the grade would likely be much more manageable for the engine. Too bad we don't have steel rails and the magnetised drivers that Tri-Ang used to do!

Another question I'd have: assuming I know the distance to cover, the total rise over that distance, and the number of bents I need, is there an easy way to figure out how tall each bent will need to be?
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Re: Incline performance?

Postby Arseny » Fri Apr 18, 2014 12:32 am

If you'll use SW1200 with only single hopper, then I am sure it will take 7% slope well.
But you should better perform a test. :wink:
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Re: Incline performance?

Postby Marquette » Fri Apr 18, 2014 1:12 am

Yeah, Arseny, that's what I'm thinking/hoping. I'll only use it with a single hopper - I'm pretty sure the trestle in reality was long enough to hold two hopper cars but I'm shortening it down - the length of the level section there on my model will be 60'.

I will indeed do a test - I need to get a bit more straight track, and to finish a hopper model at least far enough to have trucks and couplers on (I'm still working on the brake piping on my first hopper!)
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Re: Incline performance?

Postby dileTTante » Sat Apr 19, 2014 12:25 am

I'm sure you know what you're doing, and your research provides prototypes, but
the idea of a diesel locomotive pushing hopper cars of coal to feed steam locomotives seems rather sad.
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Re: Incline performance?

Postby Marquette » Sat Apr 19, 2014 12:49 am

Why sad? Light little diesels shoving coal up to feed the big beautiful K4's! :D
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Re: Incline performance?

Postby krokodil » Sat Apr 19, 2014 1:18 am

Marquette wrote:Yeah, Arseny, that's what I'm thinking/hoping. I'll only use it with a single hopper - I'm pretty sure the trestle in reality was long enough to hold two hopper cars but I'm shortening it down - the length of the level section there on my model will be 60'.

I will indeed do a test - I need to get a bit more straight track, and to finish a hopper model at least far enough to have trucks and couplers on (I'm still working on the brake piping on my first hopper!)


In worst case you can help with a supermagnet. Glue one to the bottom of the diesel and put thin metal sheets under the ties and you will see the improvement in performance. I am using the same trick on my TTe (6.5 mm) narrow gauge mine railroad.
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Re: Incline performance?

Postby Marquette » Sat Apr 19, 2014 1:21 am

Okay now that is a very interesting idea!

Could you clarify for me what a supermagnet is?
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Re: Incline performance?

Postby Arseny » Sat Apr 19, 2014 2:35 am

I think it would be better to use traction tires in this case.
But I tested SW1200 on my layout and it took 8% slope on 310-mm radius curve (!) with 2 boxcars.

But you are to use good trucks (Gold Coast ones or something like that), because cars must run easily. I have some old hoppers with some plastic wheels and trucks that I've purchased on Ebay and they did not run well.
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