[copperpen]

Might get a better visual result by using the Locomotive Forces page. You will be able to see all locomotives there, not just the ones that the train forces page gives. I have a heavy consist using three SD70Ace locomotives. Comparative testing in dry conditions using 100% adhesion and 0% change gives different results in v1.1 and the latest X version 3656.

In both versions all three locomotives are contributing motive force to move the consist. Motive force is a consistently falling figure as speed increases. Adhesion levels in snow as expected are reduced.

If however the motive power is mixed with different HP locomotives, then it is the highest rated engine that will slip first. I set up a test consist using an SD70m (4000HP), an SD40-2 (3000HP) and a C30-7 (3000HP) and no matter which position the SD70m was in, it was always the first engine to slip.

[steamer_ctn]

copperpen, on 31 October 2016 - 04:05 AM, said:

Might get a better visual result by using the Locomotive Forces page. You will be able to see all locomotives there, not just the ones that the train forces page gives.

Thanks Copperpen.

You are correct that the Locomotive Forces page will give a better view, as the Forces Information page may not show both of the locomotives (especially on long trains), so it appears I may have fallen into the trap of missing lines of stock info on the Forces Information page.

Aah, the challenges of doing quick tests. http://www.elvastower.com/forums/public/style_emoticons/default/sign_oops.gif

So all appears to be ok, I think?

[edwardk]

copperpen, on 31 October 2016 - 04:05 AM, said:

Might get a better visual result by using the Locomotive Forces page. You will be able to see all locomotives there, not just the ones that the train forces page gives. I have a heavy consist using three SD70Ace locomotives. Comparative testing in dry conditions using 100% adhesion and 0% change gives different results in v1.1 and the latest X version 3656.

In both versions all three locomotives are contributing motive force to move the consist. Motive force is a consistently falling figure as speed increases. Adhesion levels in snow as expected are reduced.

If however the motive power is mixed with different HP locomotives, then it is the highest rated engine that will slip first. I set up a test consist using an SD70m (4000HP), an SD40-2 (3000HP) and a C30-7 (3000HP) and no matter which position the SD70m was in, it was always the first engine to slip.

Thanks for reminding me about the forces page. I will check this with the train that started it all. Regarding mixed locomotives, I have read that the newer locomotives are actually better when it comes to adhesion, but evidently the current physics does not reflect this.

Edward K.

[edwardk]

steamer_ctn, on 31 October 2016 - 12:03 PM, said:

Thanks Copperpen.

You are correct that the Locomotive Forces page will give a better view, as the Forces Information page may not show both of the locomotives (especially on long trains), so it appears I may have fallen into the trap of missing lines of stock info on the Forces Information page.

Aah, the challenges of doing quick tests. http://www.elvastower.com/forums/public/style_emoticons/default/sign_oops.gif

So all appears to be ok, I think?

This is where I would have to think that all is not Ok. If you look on youtube for a stalled CSX manifest train, one that should come out on top is a train that was stalled on a combination grade and wet tracks. In this situation, there was just enough hp to run the train on level ground since the makeup was one AC4400CW and one SD40-2(I believe). The train was unable to make it up the grade so they had to break the train down to get it up the grade. It should be quite evident that if the train had an additional locomotive then this would not have happened. The adhesion value used may be close to realistic values, but the physics may not be reflecting this since the consist mentioned at the beginning of this post should be able to make it without any wheelslip. Other than sticking with simple adhesion, I normally do not mess with the adhesion options. Default settings are used.

Note: I tried going back to activity/train that started it all and I have to say that this activity will not work with advanced adhesion in its current state. I tried reducing the throttle to no more than N2, but as the grade value hit 1.6%, I started losing forward momentum due to lack of throttle. When I changed to N3, I started getting the wheelslip message and like I mentioned before, sanding does not help at all. In my opinion, you may have to consider changing the adhesion value being used since it does not make sense that mixed locomotives may be having more of an issue then lets say a train with all ES44DC locomotives.

Keep in mind that this is using the default which is the Mass(). I am sure the overall axle weight is lighter than the total Mass() so I would believe this situation would be worse.

I will have to pass on testing steam locomotives. I am a diesel person and I am not that experienced operating steam locomotives the way they should be operated.

Edward K.

[copperpen]

When you say default settings are used, do you mean you are using standard MSTS eng files. If so, that is part of the problem because they have a derated HP figure to allow for friction looses in the transmission. For Open rails this should be the full HP figure for the locomotive.

EDIT:- I have the route and activity so will give it a shot tomorrow.

[edwardk]

copperpen, on 31 October 2016 - 02:09 PM, said:

When you say default settings are used, do you mean you are using standard MSTS eng files. If so, that is part of the problem because they have a derated HP figure to allow for friction looses in the transmission. For Open rails this should be the full HP figure for the locomotive.

EDIT:- I have the route and activity so will give it a shot tomorrow.

I was referring to the adhesion settings in the options tab. I have been updating my locomotives with the full hp along with adding the ORTSDavis_A,_B,_C lines.

Would you know if the MaxContinuousForce() value is derated under OR? One area that I have not been able to work with yet is the ORTS parameter that sets up the tractive effort based on notch setting.


Edward K.

[edwardk]

Here is more information. Going back to the activity, I found that if you start using sand as soon as you start hitting the grade, there is some wheelslip, but not enough to stop the train. The problem appears to be if you start using the sand after the fact. For some reason the sand process is not countering the critical wheelslip once its already started.

Edit: Once the "red" wheelslip message is shown, sanding does not work.

Edward K.

[ATW]

What's the sanding speed cut off switch in ENG? Probably try setting them to 30-40MPH

[copperpen]

First run, only changed the HP figure to max and changed NumWheels from 4 to 2. Extended sanding to 25mph. Managed to get to run5 but that was on the verge of wheelspin even with sand. Highest speed was 22.5mph but that fell off quite fast once the train hit the initial 2.4% grade and as speed fell, TE went up leading to wheelspin once again, but only from the higher powered engines. Using my standard advanced adhesion setup of 100% with 0% changes. Got about halfway through the 2.4% grade, then stalled.

Second run with curve resistance off, got about 200 yards further up the hill and stalled.

Third run changed to MSTS adhesion and went up the hill with no problems at 18 to 21 mph. No sanding required.

Train weight is 5388 tons-US and length is 4529.5 feet.

So, I added three helpers at the rear, 2 x ES44AC and a gp38-2 and reset my adhesion back to the same as run 1 with curve resistance o09n again as well. Went all the way up the hill mostly in in notch 5, using sand when the grade was 2% or higher.On the slightly lesser grades there was a wheelwslip warning, but no actual wheelslip. So, my conclusion is as Peter suggests, make the train smaller/lighter, or add more power when running in snow.

Far as sanding not working in red wheelslip conditions, I would not expect it too, because the remedy for that is close the throttle, wait for wheelslip to stop and then apply sand to regain traction.

[steamer_ctn]

I believe that this thread demonstrates the need to establish a clear set of expectations in regards to the load hauling capabilities of the train locomotives.

Ideally this information should be sourced from working timetables for the relevant railway company.

However, this is not always readily available, and I will look at adding some generic guidelines for diesels on my website to provide some workable approximations.

In the meantime, I have found this document which provides some guidance in estimating the appropriate load for Indian trains. Whilst the Indian locomotives are probably not exactly the same specifications as the locomotives in our scenario, the document will give us some ballpark figures to work with.

The first part of the document describes the type of features that impact on the load hauling capacity, such as the TE of the locomotive, the ruling gradient, sharpest curve, weather conditions, etc.

Based upon my understanding of the train in our scenario, it appears to be pulled by one or more 4,000hp locomotives and weigh 5388 tons-US (4887.911 tonnes).

If we study the tables starting on pg 45 (46 of pdf) we can see the weights applicable to a 4,000hp locomotive (with an adhesive weight of 126 tonnes). It can be noted that these tables are for wet rails (so less then what a train can haul in dry conditions, but snow conditions, as in our scenario, would be "worse" again), and show the the impact of curve radius, gradient, and the desired speed of operation.

So in our scenario, it appears that the ruling gradient is 2.4% (~ 1 in 40), and I am not sure what the ruling curve radius is, but for the sake of illustration lets assume a 2 deg curve (~ 850m - pg 46). The table shows that a single 4000hp locomotive can haul a starting load of approximately 1580 tonnes in the section based upon our assumptions, and if we wished to maintain the train speed at 20kmh, then we could haul 1355 tonnes. Note that as the speed increases the haulage load decreases.

Thus if we wanted to haul a load of 4887 tonnes at 20kmh in the above scenario section we would need at least 4 x 4000hp (16000hp) or alternatively 1 x 4000hp + 4 x 3000hp locomotives. For good measure, we may even need to add an extra one as the tables are for wet conditions, and we are operating in snow conditions.

Thus it appears that Copperpens results and the reference document tend to align.

My suspicion is that many activities may be designed to work in MSTS, which has a different physics engine then OR. Thus I believe that some activities may need to operate in Simple Adhesion mode where an activity train load does not align with real operating practice.

The other thing that may need to be considered in the testing of our scenario, is the physics of the wagons in the consist, as whilst the locomotives appear to have been modified, the wagons may not be currently set optimally. If they are adding extra resistance to the train, then the load hauling capability of the train may be reduced even further.