[MOC] My LEGO Renfe S-130

[L-Gauger]

6 hours ago, Imanol said:

The 1x4 crossed technic bricks allows the bogie to have the same length as before but I´m not so sure about it´s stability (although Studio says it´s more stable)

As long as the plates you use in the upper part of the bogie are long enough, this should be fine. But I think the best solution is your idea of combining both techniques. I'd use the 4x4 Technic Brick technique on the end nearer to the coupler/pilot for the best stability, and the 1x4 Technic Brick on the end farther from the coupler/pilot to keep the same overall length as your previous design. For extra safety, I'd also rebuild the gearing so that it is a mirror image of what you have now. That way, the greatest stress will be on the side with the 4x4 Technic brick. 

[Imanol]

12 minutes ago, L-Gauger said:

As long as the plates you use in the upper part of the bogie are long enough, this should be fine. But I think the best solution is your idea of combining both techniques. I'd use the 4x4 Technic Brick technique on the end nearer to the coupler/pilot for the best stability, and the 1x4 Technic Brick on the end farther from the coupler/pilot to keep the same overall length as your previous design. For extra safety, I'd also rebuild the gearing so that it is a mirror image of what you have now. That way, the greatest stress will be on the side with the 4x4 Technic brick. 

Right now I don't have the program open but when I was testing the stability I found that when using the 4x4 in the rear, the coupler was not supported enough as there is only one stud of support. I did try attaching a 1x4 to it but the improvement was not very noticeable. I will try tomorrow to make the opposite design and look if it's better

[zephyr1934]

On 8/8/2025 at 11:01 AM, Imanol said:

The 1x4 crossed technic bricks allows the bogie to have the same length as before but I´m not so sure about it´s stability (although Studio says it´s more stable)

With the 32324 Brick the bogie is one stud longer which can cause issues but due to the slanted design of the train undercarriage, the bogie can be one stud longer on the frame part. 

To keep the bevel gears in place I'd suggest that fill the available space on the axles with full and half bushings or the 1x1 technic "liftarms" (in quotes because they really are just a hollow tube). Just make sure there's a little slack on the axles so they can still freely turn.

By the way, it looks like there is now room to use one of the technic connectors for the central axle coming from above

 

 or 

(I mistyped the image AND part number for the first connector in my previous note, should be 48496)

 

[BB616583]

On 5/31/2023 at 4:41 PM, Imanol said:

Salut tout le monde, je vous présente ma deuxième version du Renfe S-130 comme Ferro-Friki l’a fait il y a quelque temps. J’avais envie de refaire ce train que j’avais fait en premier en 2018 avec pas le meilleur résultat donc j’ai maintenant fait cette version en 7 goujons.

LEGO Renfe S-130 DEF [MOC] par Imanol, en Flickr

L’ensemble est très détaillé, même à l’arrière des voitures motrices et des voitures d’extrémité

LEGO Renfe S-130 Testeros Interiores [MOC] par Imanol, en Flickr

J’ai fait un train réduit de seulement 7 voitures au lieu des 11 qu’il y a dans la vraie vie, mais il a une de chacune des différentes voitures qui forment le vrai train avec des intérieurs détaillés.

D’abord l’extrémité « Preferente » et « Preferente »

LEGO Renfe S-130 Lateral Extremo Preferente [MOC] par Imanol, en Flickr

LEGO Renfe S-130 Lateral Preferente [MOC] par Imanol, en Flickr

L’intérieur des voitures « Preferente »

LEGO Renfe S-130 Interior Preferente [MOC] par Imanol, en Flickr

La voiture adaptée « Preferente » et son intérieur

LEGO Renfe S-130 Lateral Preferente PMR [MOC] par Imanol, en Flickr

LEGO Renfe S-130 Interior Preferente PMR [MOC] par Imanol, en Flickr

La voiture-café et son intérieur

LEGO Renfe S-130 Cafétéria latérale [MOC] par Imanol, en Flickr

LEGO Renfe S-130 Cafétéria intérieure [MOC] par Imanol, en Flickr

Et les voitures Turista qui sont les mêmes que preferente mais avec une disposition des sièges 2+2

LEGO Renfe S-130 Lateral Remolques Turista [MOC] par Imanol, en Flickr

LEGO Renfe S-130 Lateral Remolques Turista [MOC] par Imanol, en Flickr

 

Et maintenant que je l’ai présenté, je veux demander de l’aide pour le construire car ce sera mon premier train lego dans la vraie vie. Le mécanisme d’attelage de voiture que j’ai installé n’est qu’à des fins esthétiques et ne fonctionnera pas dans la vraie vie. Un autre problème est que j’ai vu de nombreux modèles dans lesquels tout l’arrière de la locomotive ou de la motrice pivote et je ne sais pas si cela pourrait être nécessaire de le faire dans ce cas. Enfin, je veux savoir comment le motoriser, étant si long, je suppose que j’aurais besoin des deux voitures motrices pour fournir de la puissance, mais je ne sais pas.

Quoi qu’il en soit, j’espère que vous apprécierez ce projet autant que j’ai aimé le concevoir

 

Really a very beautiful reproduction! The detail and the typical colors of the Renfe 😍

[Imanol]

16 hours ago, zephyr1934 said:

To keep the bevel gears in place I'd suggest that fill the available space on the axles with full and half bushings or the 1x1 technic "liftarms" (in quotes because they really are just a hollow tube). Just make sure there's a little slack on the axles so they can still freely turn.

By the way, it looks like there is now room to use one of the technic connectors for the central axle coming from above

 

 or 

(I mistyped the image AND part number for the first connector in my previous note, should be 48496)

 

During the testing phase on the real model I had several Technic bushings of both types but I haven´t added them to the renders.

The problem with the way of connecting the axles is that both of the pieces are in the way of the only piece which guides (as is not even really attached) the motor axle with the bogie. In this picture it can be seen, is the 3709b plate and 15535 tile on top:

When I tried to remove them and test any of the connectors I found that they are slightly taller so they cannot fit on the current footprint. There is a 3x3 hole in the chassis of the power car for the bogie to connect to the motor but right now I have an idea to make it smaller in order to keep the axle straight (in case this is part of the issue).

I think I have enough pieces to test the prototype with the 1x4 technic bricks so in the coming days I will try to build it and test if there is any issue remaining. If this fails I will start thinking of a major redesign (again) that is focused on a technic structure and could be able to incorporate one of those connectors on a similar foot print. 

The other issue right now is deciding if it´s worth it to try and order bearing wheels for the non-powered axles on the power car, in case there is a excessive friction problem on top of the design mistakes on the bogie.

Thanks for all the help, Imanol

2 hours ago, BB616583 said:

Really a very beautiful reproduction! The detail and the typical colors of the Renfe 😍

Thank you very much. This project has been a tremendous undertaking and looking at the photos on the first post is easy to see how much it has improved. If everything goes okay, and I solve the current issues, I will try finishing the decals and posting the complete project in September

[Imanol]

 

Today I have been able to test some of the ideas on the train itself. Due my "small" piece collection I haven´t been able to test everything I would have like.

The first idea tested was the one I mentioned before with the two 1x4 technic bricks in place of the 1x2 bricks. After the first failed test I modified the side details to be 1x2 instead of 1x4 rounded plates as I was noticing that they might be causing more friction.

Unfortunately the test failed when the power car was coupled to 3 of the cars that had a weight of 1.5 kg aprox. My feeling is that as right now the only pieces which bridges the gap between the two axles are two 1x8 plates, I think they don´t apply enough force and in fact, I appreciate a slight bending. This I think is pulling apart the two 1x4 bricks and causing them to drop (although this is only my theory).

On 8/8/2025 at 11:58 PM, L-Gauger said:

As long as the plates you use in the upper part of the bogie are long enough, this should be fine. But I think the best solution is your idea of combining both techniques. I'd use the 4x4 Technic Brick technique on the end nearer to the coupler/pilot for the best stability, and the 1x4 Technic Brick on the end farther from the coupler/pilot to keep the same overall length as your previous design. For extra safety, I'd also rebuild the gearing so that it is a mirror image of what you have now. That way, the greatest stress will be on the side with the 4x4 Technic brick. 

Taking inspiration on this idea I did my own version but changing the 4x4 with a 4x6 as I don´t have any of the 4x4. The result is promising although the front is still experiencing the same issue as before. The power car was able to pull the other 3 cars although going very slowly but when trying to traverse a switch, the same issue as before occurred.

 

Right know I don´t want to make a piece order as I´m still not sure of what is exactly the issue, although I think trying a 4x4 brick in the front could work. I will try to make some temporary modifications to the power car in order to be able to use a 4x6 in the front and see if that solves the issue.

Currently I´m running out of batteries so I can´t continue testing until tomorrow.

Finally I would like to know if someone has carried out some test with the powered up motor and has the maximum load it can pull, I know that my train is quite heavy as it has a complete interior but I don´t know if that is really the issue.

Thanks for all the ideas, Imanol

[L-Gauger]

Good test results! Sorry my ideas didn't quite work as I thought they would. Although I do have more thoughts based on your test results... 

Is it possible for you to move the pivot point of your truck forward (or back) by 1/2 stud? This would allow you to connect the two 1x4 Technic bricks via a 2x6 Technic plate and offer a bit more resistance to warping. Another way might be to use 1x10 or 1x12 plates to take the place of the 1x8 plates. The longer plates have more clutch power. 

Finally, just to verify: are you using all four of the studs on the 1x4 Technic Bricks to attach the bricks to the rest of the bogie frame? If not, find a way to do so in order that you might take advantage of all the clutch power you can. 

You are most welcome! I like the mechanics of engineering drive trains with Lego. I haven't done tests with PUP motors, but my PF motors continue to surprise me. One motor might work, but I'd do two if I could afford it, at the very least to reduce stress on all parts. 

[Imanol]

11 hours ago, L-Gauger said:

Good test results! Sorry my ideas didn't quite work as I thought they would. Although I do have more thoughts based on your test results... 

You don´t need to apologize as I haven´t been able to properly test everything due to lack of parts on my collection. In this case i´m missing the 4x4 technic brick, so I cannot know if that option might work.

11 hours ago, L-Gauger said:

Is it possible for you to move the pivot point of your truck forward (or back) by 1/2 stud? This would allow you to connect the two 1x4 Technic bricks via a 2x6 Technic plate and offer a bit more resistance to warping. Another way might be to use 1x10 or 1x12 plates to take the place of the 1x8 plates. The longer plates have more clutch power. 

I was about to try and do that when I realized that it will require to move the whole motor assembly inside and unfortunately there is not enough space (due to the motor clips) and to fit it I would need to make a big redesign. Using a longer plate might be possible as yesterday I realized that the connection of the rear section can be offsetted without all of the supports that I have in place.

11 hours ago, L-Gauger said:

Finally, just to verify: are you using all four of the studs on the 1x4 Technic Bricks to attach the bricks to the rest of the bogie frame? If not, find a way to do so in order that you might take advantage of all the clutch power you can. 

Both 1x4 are supported by a 1x2 plate on the center studs and the longitudinal 1x8 on the outer study so in they are well connected.

11 hours ago, L-Gauger said:

You are most welcome! I like the mechanics of engineering drive trains with Lego. I haven't done tests with PUP motors, but my PF motors continue to surprise me. One motor might work, but I'd do two if I could afford it, at the very least to reduce stress on all parts. 

Right now, my main limiting factor is that my lego parts come from city sets from my childhood and whatever remnants I have from the piece orders of this project. I would like to have enough pieces to be able to test different solutions but the only way is buying more pieces and wait for them to arrive.

Due to the slanted front of the train I discovered that there is not enough space available for another motor in the front bogie so the only other way would be to a complete redesign and use non-train PUP motors using a design similar to the one used by @Ferro-Friki on his S-102 and that will require building the powercars from scratch.

For now I will try to make the necessary modifications to the power car to test with the 4x6 technic brick on the front axle and see if there is another failure point before deciding on a final design and making a piece order.

Thanks for all the ideas, Imanol

[L-Gauger]

13 hours ago, Imanol said:

I was about to try and do that when I realized that it will require to move the whole motor assembly inside and unfortunately there is not enough space (due to the motor clips) and to fit it I would need to make a big redesign.

Gotcha. 

13 hours ago, Imanol said:

Using a longer plate might be possible as yesterday I realized that the connection of the rear section can be offsetted without all of the supports that I have in place.

13 hours ago, Imanol said:

Both 1x4 are supported by a 1x2 plate on the center studs and the longitudinal 1x8 on the outer study so in they are well connected.

Brilliant! 

You know, I wonder if a pair of 1x1 round plates might have just the teeniest bit more clutch power than the 1x2 plates... but might not be enough to make much difference. 

13 hours ago, Imanol said:

Right now, my main limiting factor is that my lego parts come from city sets from my childhood and whatever remnants I have from the piece orders of this project.

I understand your situation! Just a thought: if "bargain outlets" (stores that make money by buying overstock from big-box stores and selling that overstock for a very low price) exist in your area, I'd check them out. When I lived near a bargain outlet I took a stroll through there weekly and bought up any Lego sets they had. I was able to add a lot of great parts, both common and rare, by that method. 

13 hours ago, Imanol said:

Due to the slanted front of the train I discovered that there is not enough space available for another motor in the front bogie

Okay, gotcha. As long as both bogies are powered, one motor (or one motor per bogie for a total of two) should suffice. 

[Imanol]

10 hours ago, L-Gauger said:

You know, I wonder if a pair of 1x1 round plates might have just the teeniest bit more clutch power than the 1x2 plates... but might not be enough to make much difference. 

I can try that, it´s the easiest modification possible and it might just work.

10 hours ago, L-Gauger said:

I understand your situation! Just a thought: if "bargain outlets" (stores that make money by buying overstock from big-box stores and selling that overstock for a very low price) exist in your area, I'd check them out. When I lived near a bargain outlet I took a stroll through there weekly and bought up any Lego sets they had. I was able to add a lot of great parts, both common and rare, by that method. 

Unfortunately there isn´t anything like that near me. Right now with all of the pieces ordered for this project I have quite a large bin of leftovers but with every new expansion I have taken pieces out. And I only have pieces that I already thought I needed for the project. 

The only good thing is that I suppose this won´t be a large order so I might try to look for interesting pieces which might be useful in the future and order them.

10 hours ago, L-Gauger said:

Okay, gotcha. As long as both bogies are powered, one motor (or one motor per bogie for a total of two) should suffice. 

Currently both power cars have only the rear bogie powered and with the battery on the middle is very difficult to connect the front bogie to the motor. For now the front bogie is completely unpowered and has it´s own modifications to strengthen it which are uncompatible with all of the gear linkage. In this picture you can see how it looks (although there is minor changes with the built model)

At this time there is a major heatwave in the south of Europe (where I live) so i´m not going to make much progress on this project until Monday when hopefully the heat will recede. For now the plan is to try and change the 1x8 plates with 1x10 or 1x12 and try testing the 4x6 technic brick on the front axle of the bogie to see if the 4x4 could work.

Thanks for all the help, Imanol

[Imanol]

Well, today I was able to resume testing with the train and my worst fears have come true. To summarize everything, the train is lacking power to move all of the cars.

This is something that I had thought before but I didn´t have enough proof of it. Looking at the available material on the internet there is no indication that this can be a problem but the testing says otherwise. 

I have replaced the front axle assembly with the 4x6 technic brick and immediately I experienced wheel slipping and what I suppose is the anti-slipping feature of the motor which is to stop turning. When the train was able to move it was quite slow and it never was able to completely traverse through a switch as the wheel friction was enough to stop it.

The tests have been done with a powercar with has a weight of 1 kg approximately pulling three train cars with a combined weight of 1.5 kg. This train has the particularity of being a Talgo and like it´s real counterpart, there is only one set of wheels per train car so that might also cause problems. Although hand pushing the cars show no issue at all.

Due to the design of the powercar and the option chosen, there is only enough space for one motor powering the rear bogie. Here it can be seen the interior distribution of the power car:

On 8/16/2025 at 12:36 AM, L-Gauger said:

Okay, gotcha. As long as both bogies are powered, one motor (or one motor per bogie for a total of two) should suffice. 

This looks like a major issue as right now there is not enough space for another motor and as I mentioned in a previous post it will require a complete redesign of the powercar. 

At this point the only other solution might be to look for aftermarket motors but I don´t know if it could be enough.

For now all of the test have been carried out with only one power car and 3 of the 5 cars. In theory each power car should only need to pull 2,5 cars but I feel that the difference is too small to be the issue and unfortunately I only have the required pieces to fix the center axle problem on one of the two bogies.

Thanks for all of the previous help, Imanol.

[idlemarvel]

How much of a change would it be to use a standard train motor at the front of the power car? It looks like it could be made to fit with a bit of tweaking.

[Imanol]

27 minutes ago, idlemarvel said:

How much of a change would it be to use a standard train motor at the front of the power car? It looks like it could be made to fit with a bit of tweaking.

It's definetely possible, in fact the train was first built with that in mind and before modifying the design I tested it like with one motor bogie, although other issues prevented a more thorough test with the full load and it was suffering from a lack of power

The train right now is powered by a sideways train motor located inside the frame. 

The main issue of using the motor directly is that is not very detailed and it's less customizable (I can't change it's direction by mirrroring a gear) and I don't if it's possible to fit two at the same time.

[idlemarvel]

13 hours ago, Imanol said:

The main issue of using the motor directly is that is not very detailed and it's less customizable (I can't change it's direction by mirrroring a gear) and I don't if it's possible to fit two at the same time.

Agreed it is not very detailed but it may be a necessary compromise. You can run two train motors off the same hub. Using Pybricks you can configure the hub so that the motor on port B runs in the opposite direction to port A. The YouTuber Battery Powered Bricks has a few videos on setting up Pybricks to do this on one of his locos.

[Imanol]

1 hour ago, idlemarvel said:

Agreed it is not very detailed but it may be a necessary compromise. You can run two train motors off the same hub. Using Pybricks you can configure the hub so that the motor on port B runs in the opposite direction to port A. The YouTuber Battery Powered Bricks has a few videos on setting up Pybricks to do this on one of his locos.

There is also another issue which I completely forgot about it but took quite a lot of time to solve which is how to attach the train plate pin to the 7 stud wide train at the correct height. This required a very complex technic contraption which unfortunately I reused the pieces in other parts of the build so I will require to make a piece order only to test this.

Right now my main doubt is knowing if it´s possible to use the 88013 motors like in the crocodile as I think there is enough room if I lower the battery box.

If this is too difficult I may go back to using the two 88011 motors as proposed.

Thanks, Imanol

[idlemarvel]

2 hours ago, Imanol said:

Right now my main doubt is knowing if it´s possible to use the 88013 motors like in the crocodile as I think there is enough room if I lower the battery box.

If this is too difficult I may go back to using the two 88011 motors as proposed.

Thanks, Imanol

Remember that the crocodile has to use an app as the remote cannot control the speed of an 88013 motor, only one speed (full speed). 

If you're tight for space you can save about a plate in height if you take the bottom off the hub - not sure you can model that in stud.io though!

[XG BC]

with pybricks you can do whatever you want.

[Imanol]

19 minutes ago, idlemarvel said:

Remember that the crocodile has to use an app as the remote cannot control the speed of an 88013 motor, only one speed (full speed). 

If you're tight for space you can save about a plate in height if you take the bottom off the hub - not sure you can model that in stud.io though!

I supposed there was some kind of issue with using the 88013.

The problem with removing the bottom of the hub is that is where is connected to the train, the top is connected only to the roof so it´s not very secure and the roof needs to be removed to turn on or off the hub.

I´ve continue doing testing and tried using a front axle without friction rings but the result it´s still the same. I have also tried searching what is the maximum load that the 88011 motor can pull but I wasn´t successful apart from finding the torque value and AI data which is not very clear.

Looking at "testing" I´ve seen trains carrying up to 10 carriages of the 60197 with 1 motor with minor wheel slipping so it doesn´t make any sense that a combined weight of 2,5 kg is causing any trouble. 

12 minutes ago, XG BC said:

with pybricks you can do whatever you want.

I tried at some point to run two hubs at the same time and I wasn´t able to use it so that might become an issue with the setup of this train as the train has two powercars

Right now I´m in a difficult situation as I will need to make a major redesign whatever the final solution chosen is but at the same time the two main ideas are quite different so I want to have the certainty that it works before making any piece order.

Thanks for all of the help, Imanol

[idlemarvel]

If you don't want to or can't use Pybricks then there is the Lego app which can control two hubs and a remote at the same time, but you will need to do some app coding. 

I assume you know you can control two hubs at the same time from a remote, as long as they are on the same channel (red, blue, etc). To reverse the motor you can physically run the motor around but you may need a 3rd party extension cable.

[Imanol]

23 minutes ago, idlemarvel said:

If you don't want to or can't use Pybricks then there is the Lego app which can control two hubs and a remote at the same time, but you will need to do some app coding. 

I assume you know you can control two hubs at the same time from a remote, as long as they are on the same channel (red, blue, etc). To reverse the motor you can physically run the motor around but you may need a 3rd party extension cable.

When I received the motors and hubs I tried using Pybricks or the LEGO app but neither option allowed for two hubs. The LEGO app was not able to detect the second hub and I was only able to use both hubs with only the remote with the LEGO software as with Pybricks it didn't let me connect the other hub

[L-Gauger]

On 8/16/2025 at 4:03 AM, Imanol said:

Currently both power cars have only the rear bogie powered and with the battery on the middle is very difficult to connect the front bogie to the motor.

Gotcha. Now that I see your render I understand a lot. I thought from the start that you were using an 88013 motor like in the Crocodile. I don't have experience with the PUP train motor, but if the internals are about like the PF train motor it is one of the lowest-torque motors produced by Lego. 

On 8/16/2025 at 4:03 AM, Imanol said:

At this time there is a major heatwave in the south of Europe (where I live) so i´m not going to make much progress on this project until Monday when hopefully the heat will recede.

Ouch! I've had a hot summer, too. You have my sympathies. 

On 8/18/2025 at 9:19 AM, Imanol said:

I have replaced the front axle assembly with the 4x6 technic brick and immediately I experienced wheel slipping and what I suppose is the anti-slipping feature of the motor which is to stop turning. When the train was able to move it was quite slow and it never was able to completely traverse through a switch as the wheel friction was enough to stop it.

I know this seems like failure, but I was happy to read this. You have gearing that actually holds together, and that is a victory. Now we just have to find the right configuration to give the engine a bit more pulling power. 

Reading your description, I think you may actually be experiencing two separate issues at once. The wheelslip means that your power car does not have enough weight on the rear bogie. The best options are: 

1. Power the front bogie. 

2. Move the PUP hub closer to the rear bogie to shift the center of gravity. 

3. Fill every gap in the power car behind the PUP hub with heavy stuff like fishing weights or coins. 

Now the motor stopping its turning and the train moving quite slow might be a different issue: those are symptoms that your motor is overheating. Likely what's wrong is that the PUP train motor is not powerful enough to overcome both the friction and weight of a full train. 

Your train is 7-wide, so the PUP motor should be able to handle it if, as @idlemarvel suggested, you use the motor to power the wheels directly (like in the Lego City train sets) and dispense with any geared drivetrain. You'll lose some detail, but it might not be all that noticeable. You shouldn't have to use two train motors per power car with this method. 

12 hours ago, Imanol said:

Right now my main doubt is knowing if it´s possible to use the 88013 motors like in the crocodile as I think there is enough room if I lower the battery box.

Assuming there is enough room, this would be the best option if it weren't for the fact that only the app can give the 88013 motor speed control. 

Worst case scenario, maybe it would be worth considering the idea of maybe converting the model to Power Functions and using a PF M motor to drive the rear bogie? PF M motors are quite respectable, and I imagine one in each power car should be able to move a 7-wide, 7-car (counting the power cars) train... 

3 hours ago, Imanol said:

When I received the motors and hubs I tried using Pybricks or the LEGO app but neither option allowed for two hubs. The LEGO app was not able to detect the second hub and I was only able to use both hubs with only the remote with the LEGO software as with Pybricks it didn't let me connect the other hub

Good to know... 

In that case, it sounds like any PUP motor other than the train motor isn't something you can practically use. If that's true, your options are either to replace the rear bogie of your power car with a PUP train motor (and accept the fact that your bogies won't be as detailed,) or convert the model to Power Functions (using PF M or L motors would preserve the bogies you have already, but you've already spent your hard-earned money on PUP components so you probably are just looking for a way to make what you've bought already work.) 

I personally would suggest trying first to replace only the rear bogie of your power car with a PUP train motor. Then test it to see if the power car has enough tractive effort to meet your needs. If so, you have a working "for-now" solution. If the look of the train motor bothers you later, you can think about re-powering the train with Power Functions motors at that future date. 

[Imanol]

11 hours ago, L-Gauger said:

I know this seems like failure, but I was happy to read this. You have gearing that actually holds together, and that is a victory. Now we just have to find the right configuration to give the engine a bit more pulling power. 

Reading your description, I think you may actually be experiencing two separate issues at once. The wheelslip means that your power car does not have enough weight on the rear bogie. The best options are: 

1. Power the front bogie. 

2. Move the PUP hub closer to the rear bogie to shift the center of gravity. 

3. Fill every gap in the power car behind the PUP hub with heavy stuff like fishing weights or coins. 

Now the motor stopping its turning and the train moving quite slow might be a different issue: those are symptoms that your motor is overheating. Likely what's wrong is that the PUP train motor is not powerful enough to overcome both the friction and weight of a full train. 

Well, yesterday I continued doing testing and I was able to rig my phone to move with the train and film the gear on the bogie axle. After reviewing the videos I noticed that the gear was moving constantly and that there wasn´t any wheelslip. But at the same time, I was able to see on the hub that the low voltage indicator was coming on constantly (even though the batteries are new) and when reaching a switch the train was stuck and not moving at all.

I also tried putting the other hub with batteries on top of the rear axle (adding like 120 grams) but it didn´t change anything.

The only time I experienced the wheelslip was when trying to reverse the train after getting stuck on the switch although the motor stopped turning almost immediately.

11 hours ago, L-Gauger said:

Your train is 7-wide, so the PUP motor should be able to handle it if, as @idlemarvel suggested, you use the motor to power the wheels directly (like in the Lego City train sets) and dispense with any geared drivetrain. You'll lose some detail, but it might not be all that noticeable. You shouldn't have to use two train motors per power car with this method. 

When I first received the motors I did a bit of testing with the previous setup which included using the train motor in the front bogie and even though the problem wasn´t as big I already noticed that it was struggling to pull the 3 cars although there wasn´t much issue traversing the switch apart from the rear of the train derailing due to the low weight and lack of guidance.

Right now it will take some work to rearrange everything on the power car to test again this setup and it might require some pieces as the bogie attachment components have been reused in other parts.

11 hours ago, L-Gauger said:

Worst case scenario, maybe it would be worth considering the idea of maybe converting the model to Power Functions and using a PF M motor to drive the rear bogie? PF M motors are quite respectable, and I imagine one in each power car should be able to move a 7-wide, 7-car (counting the power cars) train... 

Looking at the data I think the difference in performance between both motors is negligible and I don´t know if I want to take the risk and end up having the same trouble. 

 

11 hours ago, L-Gauger said:

Gotcha. Now that I see your render I understand a lot. I thought from the start that you were using an 88013 motor like in the Crocodile. I don't have experience with the PUP train motor, but if the internals are about like the PF train motor it is one of the lowest-torque motors produced by Lego. 

Assuming there is enough room, this would be the best option if it weren't for the fact that only the app can give the 88013 motor speed control. 

Looking at the stats for the motors on here: https://motors.sariel.pl/ it looks like the 88013 has much more torque but very low rpm so it might be quite slower. The fact that it can only be controlled by the app will make this impossible to control so I think this option might need to the discarded entirely

11 hours ago, L-Gauger said:

Good to know... 

In that case, it sounds like any PUP motor other than the train motor isn't something you can practically use. If that's true, your options are either to replace the rear bogie of your power car with a PUP train motor (and accept the fact that your bogies won't be as detailed,) or convert the model to Power Functions (using PF M or L motors would preserve the bogies you have already, but you've already spent your hard-earned money on PUP components so you probably are just looking for a way to make what you've bought already work.) 

I personally would suggest trying first to replace only the rear bogie of your power car with a PUP train motor. Then test it to see if the power car has enough tractive effort to meet your needs. If so, you have a working "for-now" solution. If the look of the train motor bothers you later, you can think about re-powering the train with Power Functions motors at that future date. 

The issue of trying to connect two hubs either with Pybricks software or with the LEGO app will create a lot of trouble as the only way I found to do that is to connect both hubs directly to the remote so I need them in different channels to make them go in opposite directions. If anyone has any idea how to solve this, it will be greatly appreciated.

For now I will try to make modify the studio model to see if I can add the train motor on the front without requiring a new piece order and if possible test with this setup in both powercars and see if it´s enough. 

Right now the hard line will be with replacing the rear bogie as is not only the side detail that needs to be removed as the entire rear connection that will need to be changed to make way for another motor changing the appearance of the train quite a lot.

Thanks for all the help, Imanol 

[zephyr1934]

I'd suggest setting the power car aside and just make an ugly "power unit" to simply see if it is possible to move the rest of the train the way you want it to move. If you can't get that to work to your satisfaction there's no point in killing yourself trying to get the detailed model to work. If you do experience slipping, adding weight above the drive wheels will help them get traction (but doing so might decrease the life of your motors, so only pursue that route if you are willing to take the risks)

In terms of other thoughts, if the train is a huge drag, ball bearing wheels will make a big improvement.

Finally, if nothing else works, one nice thing about PU is that you can throw multiple hubs at the problem. So instead of just one power car you could have distributed power units throughout the train.

[Imanol]

12 hours ago, zephyr1934 said:

I'd suggest setting the power car aside and just make an ugly "power unit" to simply see if it is possible to move the rest of the train the way you want it to move. If you can't get that to work to your satisfaction there's no point in killing yourself trying to get the detailed model to work. If you do experience slipping, adding weight above the drive wheels will help them get traction (but doing so might decrease the life of your motors, so only pursue that route if you are willing to take the risks)

I would like to do something like that but the fact is that right now I have very limited quantities of pieces available, specially technic components, so is very difficult to make something simple. When I only had one power car built I was able to take the other motor bogie and making some kind of contraption put the motor on top but it wasn´t very stable and I only used it to control the rear of the train when testing the main locomotive. I have already tried adding weight on top of the motor but there hasn´t been any improvements with an added 120 g.

12 hours ago, zephyr1934 said:

In terms of other thoughts, if the train is a huge drag, ball bearing wheels will make a big improvement.

This is something that can be used but I don´t know how much will improve as the passenger train cars are built with the 38339 wheel holder instead which in theory doesn´t have as much friction.

12 hours ago, zephyr1934 said:

Finally, if nothing else works, one nice thing about PU is that you can throw multiple hubs at the problem. So instead of just one power car you could have distributed power units throughout the train.

This unfortunately won´t never work with this design. This train is based on a real train made by Talgo, the main thing about this trains are that there is only one axle per car with the other side of the car resting on the following car. This is completely different from conventional train cars which have two bogies which could be motorized in this situation. Here is a picture of how it looks (the final axle should be part of the next car):

At the same time this design is supposed to be lighter than any other type of train but that doesn´t translate well into LEGO as the cars required a complete technic frame on the inside to prevent them from buckling.

There is also the wheel guidance issue which I suppose is the problem that is experiencing when reaching the switch but after doing tests pushing the cars by hand they can go through the switch with no trouble.

RIght now I need to find a way of attaching the pin from the motor bogie on the front of the power car but this doesn´t look to be easy as there is 5 1x16 technic beams used as reinforcement which need to be partially removed and then I need to see how to add another technic contraption to connect the bogie. Apart from that the only thing I can try is to look for a way of building a one bogie "shunter" to try and pull the cars but I won´t be able to make anything close to the size of the current power car.

Thanks for all of the help, Imanol

 

[Phil B]

Not directly related to solving any of the problems you are facing with this build, but for me this is the magic of building trains in LEGO: Often you are stumped on a problem, which seems unovercomeable .... and then your brain starts working overtime. Maybe after doing something else for a while, maybe after a few nights of sleep, something will come into your head that allows you to think about the problem differently and unlocks you ... and you can move on until you hit the next roadblock.

Many examples here of people who have been working on a train build for many years - either waiting for the right pieces to be produced by LEGO, or just tinkering over-and-over until things are just right.

Keep on keeping on, @Imanol!