Elvas Tower: Wheel Slip on steam locomotives - Elvas Tower

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Wheel Slip on steam locomotives Rate Topic: -----

#1 User is online   ATSF3751 

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Posted 09 March 2022 - 03:37 PM

When it comes to wheel slip it should depend on factor of adhesion, the amount the throttle is open, the weight of the train along with a few other factors like weather, wet or dry rail, grease on the rail, and even shadow over the tracks. The greatest effort is required from a locomotive when it is just starting. At this time, if the engineer applies too much power to the wheels the turning force applied to the wheel will greatly exceed the opposing friction force affected by the surface of the rail, and the wheel will turn without being able to move the train forward. If the engineer does not take quick corrective action the locomotive can end up with its wheels spinning drastically. This in turn can damage both the locomotive drive mechanism by running too fast, and the rail surface, which, in extreme cases, can be left with a dip where the spin took place.

Some locomotive types were more prone to this phenomenon than others. Also, the effect is much more likely to occur with a heavier train or where the rail surface is compromised, for example, during wet or icy weather, or when there is oil or leaves on the track.

Open Rails only has wheel slip set up for diesels and not steam locomotives as far as I am aware. I still have the original MSTS installed on my PC and looking at steam locomotives in there it does a much better job with wheel slip when it comes to steam locomotives vs Open Rails. Why doesn't the Open Rails team just put the coding for steam locomotive slip from MSTS into Open Rails and then tweak it later on? It would be a lot more realistic then what we have currently in Open Rails. Open Rails reacts like this locomotive in this video. Maybe we should add sparks to the wheel slips as well when it gets that violent. Another thing to think about when it comes to wheel slips is it is possible to suck the fire right out of the firebox when its that violent because of the draft it is creating.

Brandon

https://www.youtube....xNMh0PFwfo&t=5s

#2 User is offline   copperpen 

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Posted 10 March 2022 - 10:58 AM

Wheelslip is present for steamers. Whether you see it or not will depend on the weight of the train, the adhesion factor of the locomotive, weather conditions and how controls are handled.

#3 User is offline   cjakeman 

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Posted 10 March 2022 - 11:21 AM

 ATSF3751, on 09 March 2022 - 03:37 PM, said:

Why doesn't the Open Rails team just put the coding for steam locomotive slip from MSTS into Open Rails and then tweak it later on?

Did you mean that the Open Rails team should extract the Microsoft's code from MSTS and copy it into Open Rails?

The Open Rails team has never had access to the code inside MSTS, so we have to create our own. That's part of the fun for coders.

#4 User is offline   Weter 

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Posted 11 March 2022 - 09:53 AM

Compound machines tend to be more easy-slipping too. (real-life ones)
ORTS uses different physics, so many MSTS-tuned steamers turn "crazy", as they weren't configured properly, though MSTS allowed that.
So the work of reconfiguring, using adequate parameters is needed in such cases.

#5 User is online   ATSF3751 

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Posted 11 March 2022 - 12:32 PM

I agree with you Weter! All steam locomotives do in Open Rails is once the wheel looses grip of the rail it spins a million miles a min and doesn't stop until you shut the throttle down completely. Only part of that is correct with real steam locomotives. Yes the slipping does not stop until you close the throttle but where Open Rails has it wrong is the drivers should not spin a million miles a min. It looks very unrealistic and I think the Open Rails team needs to watch some videos on what it looks like when a real steam locomotive slips. It is nothing like a diesel wheel slip. Also when a steam locomotive slips you should never turn the sanders on until after the drivers stop slipping. Doing so could damage the linkage and rods. Here are a few videos I found of steam locomotives slipping just to give you a general idea of what it should look and sound like. The way Open Rails has steam locomotives slipping you would literally rip the running gear all apart in real life.

Brandon

https://www.youtube....h?v=upw1PAiTG7Y

https://www.youtube....h?v=OqUYjRzUis4

https://www.youtube....h?v=T9UYYyDOJXQ

https://www.youtube....h?v=kj6M-xMw0yY

https://www.youtube....h?v=pl59l2ilfRM

https://www.youtube....CqFfso1Q&t=256s

#6 User is offline   steamer_ctn 

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Posted 11 March 2022 - 05:25 PM

 ATSF3751, on 09 March 2022 - 03:37 PM, said:

Open Rails only has wheel slip set up for diesels and not steam locomotives as far as I am aware.
Wheel slip is included in OR for diesel, electric and steam locomotives.

Wheel slip for diesel/electric locomotives occurs differently to steam locomotives, and therefore cannot be compared directly. It is thus implemented differently in OR for each of these types of locomotives.

For example the rotation force applied to a diesel/electric wheel is constant throughout the full wheel rotation, whereas on steam locomotive it varies due to the gearing of the wheels. Also a lot of diesels/electrics have some form of slip control that reduces the force on the wheel when slip starts to occur. A steam locomotive requires the driver to manually control the wheel slip.

 ATSF3751, on 11 March 2022 - 12:32 PM, said:

I agree with you Weter! All steam locomotives do in Open Rails is once the wheel looses grip of the rail it spins a million miles a min and doesn't stop until you shut the throttle down completely. Only part of that is correct with real steam locomotives. Yes the slipping does not stop until you close the throttle but where Open Rails has it wrong is the drivers should not spin a million miles a min. It looks very unrealistic and I think the Open Rails team needs to watch some videos on what it looks like when a real steam locomotive slips. It is nothing like a diesel wheel slip. Also when a steam locomotive slips you should never turn the sanders on until after the drivers stop slipping. Doing so could damage the linkage and rods. Here are a few videos I found of steam locomotives slipping just to give you a general idea of what it should look and sound like.
The videos appear to show controlled slip scenarios, ie where the driver closes the throttle as soon as slip starts to occur.

Typically when wheel slip occurs, the friction between the rail and the locomotive wheel decreases significantly, and hence if left uncontrolled the wheels will accelerate to a very high speed. The only way to bring a wheel slip under control is to reduce the power to the wheels, ie close the throttle, or in some instances use the reverser (though many drivers do not agree with reverser control of wheel slip). In the second video it is very clear that the driver is closing and opening the throttle to try and control the wheel slip as it pushes the other locomotive into the shed.

 ATSF3751, on 11 March 2022 - 12:32 PM, said:

The way Open Rails has steam locomotives slipping you would literally rip the running gear all apart in real life.
That is exactly what can happen, and whilst OR models the significant increase in speed, it is forgiving of the driver, by currently not destroying his valve motion at excessive wheel speed. This could be included in OR to motivate the driver to control any wheel slip.

This page describes an uncontrolled wheel slip scenario, and subsequent damage.

It will be noted from the description that the wheels reached a rotational speed of 140mph before the force to the wheels was removed by the destruction of the cylinders and the wheel motion gear. Presumably if these elements had not failed when they did, then the wheel rotational speed could have increased to an even higher speed.

So just like in real life, wheel slip needs to be controlled otherwise excessive wheel rotational speeds can occur.

#7 User is online   darwins 

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Posted 11 March 2022 - 11:08 PM

 steamer_ctn, on 11 March 2022 - 05:25 PM, said:


That is exactly what can happen, and whilst OR models the significant increase in speed, it is forgiving of the driver, by currently not destroying his valve motion at excessive wheel speed. This could be included in OR to motivate the driver to control any wheel slip.



Please don't include that unless you can give us a faster way to close the throttle. Even though you have to use physical force in real life, most drivers can do this very quickly. In OR if you are outside the cab, it seems like you have to keep your finger on the A key for a long time to achieve the same.

#8 User is online   darwins 

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Posted 11 March 2022 - 11:13 PM

Also I think something like I have described below can happen in real life. Maybe steam driver's or firemen can confirm.

Wheels slip briefly as you pass over a small patch of low adhesion - due to loco standing and oil and water dropping perhaps - and that grip is regained even before the driver has closed the regulator as the wheels move on to drier or cleaner rail or somewhere that has already been sanded.

#9 User is offline   Weter 

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Posted 12 March 2022 - 03:58 AM

@Brandon
Hello.
My mate tought me one hack:
When You correct "https" to 'http" in YouTube links, there will be small windows with video in your post, instead of just links.

Sadly, this works not always: then link text turns gray and stops redirecting to YT: roll your edition back to https then.

#10 User is offline   RR1 

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Posted 12 March 2022 - 05:52 AM

 darwins, on 11 March 2022 - 11:08 PM, said:

Please don't include that unless you can give us a faster way to close the throttle. Even though you have to use physical force in real life, most drivers can do this very quickly. In OR if you are outside the cab, it seems like you have to keep your finger on the A key for a long time to achieve the same.

Then what about introducing (another!?!) keystroke that sets the throttle to zero (or some appropriate low percent) in say half a second to try to more realistically respond to wheelslip? Perhaps the throttle reduction time and reduction level could be specified in the eng file as I'm sure they would vary somewhat between different engines.

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