Designing bogies with 3 axes for an E-locomotive

[slagbijnieuwpoort1600]

Dear all,

I recently became interested in building Lego/other building brick trains, to accompany the Lego trains of my son. I recently bought three second-hand Bluebrixx 8W Rheingold carriages, so now they also need to be pulled by an appropriate locomotive. I decided to try if I could design/MOD one myself. Because I’m living in the Netherlands I would like to build a NS 1200 locomotive, to recreate trains like this: https://www.flickr.com/photos/cklx/44453150825/

I started off with the stud.io file that I found on https://www.mybricks4u.com/trains---loc.html with a design from jokey02, because I thought it would a bit hard to completely start from scratch. Of course I also looked to the nice model of UrbanErwin as an inspiration https://www.eurobricks.com/forum/index.php?/forums/topic/182433-moc-ns1202/. I changed the main colour to dark blue and added a yellow line and red parts, I added 4 studs to the length of the locomotive and added extra lights to the front. I find it however more difficult to change the design of the technical parts just via a digital model. The thing I am not sure about are:

·         The bogies in the design by jokey02 consist of 2 14-studs long technic bricks that are 4 studs apart. This means that these will hardly go through any curve, am I right? As I have seen in other models there are four different ways to solve this:

1.          Make the bogie only 3 studs wide in the middle, so that the wheels on the middle axis could move from left to right. This is comparable with e.g. the Bluebrixx Flying Scotsman 103481. It might however become tricky to motorize the bogie, as there will be not much place left for gears and an extra technical axis in the middle of the bogie?

2.          Make it possible for the whole centre part of the bogie to move left and right, like with the Lego Orient Express 21344. Motorization the becomes probably even more difficult with this option.

3.          Replace the wheels in the middle by blind drivers, this is I think the most common way to do this for e.g. steam locomotives. These blind drivers look usually still a bit odd in my opinion, but for this particular locomotive the blind driver will be mostly covered by the side decorations, so it might be a good solution here as well.

4.          Split the bogie into two parts, one with to axes and one with one axis, as is done e.g. with the Bluebrixx BR 103 in 8w, 104283. This makes it easy to motorize it with a train motor, however also this solution looks a bit odd aesthetically, especially in curves.

Which would have your preference if you were building a locomotive? The main curves on our railway track are R88 and R104, and although it would also be nice if the locomotive could move on R40 switches it isn’t strictly necessary.

·          The second decision I have to make is how to motorize the locomotive. Solution 1 to 3 in the bullet above will all make it necessary to make use of M, L or XL motors if I’m not mistaken. Meanwhile with option 4 I could also choose for RC train motors (or even 9V if I would have had the rails for that solution). How do you pick what is the right motor and the right gear, is a bigger motor always better as long as it fits in the locomotive?
And the gears, do you usually pick them so that in the end the locomotive can travel at ca. 1 m/s or 3 to 4 km/h, given the maximum number of rotations per minute of the motor at 9V?

·          I noticed that the magnetic couplers of the locomotive designed by jokey02 are attached to the locomotive body, and not to the bogies. While this is the same as in the original (and as I understand one main reason why I run much better then e.g. the NS 1100), I have not much seen this at Lego/brick-built locomotives. Would I need to change this, or is this all right as long as the pivot point of the bogie is not too far away from the coupler? What is then considered ‘not too far away’, or does that also depend highly on the wagons the locomotive will be pulling?

·        Is it more in general possible to design the technical part of a motorized locomotive digitally? Or would you always make sure you have some extra parts to experiment with different possibilities/configurations?

Thank you a lot for the advice!

[zephyr1934]

It depends on the scale and level of accuracy you are aiming for. If you don't mind keeping a "Lego" feeling in the model, at 6 wide a quick and easy "3 axle" bogie simply uses three wheel holders with axles in only two of them.

At 8 wide you could build motor frames for the same effect.

 

I've got a non-lego soluition where I make motor sides with fake axles, but they are a little pricey and the style might not match your prototype.

 

 

1 hour ago, slagbijnieuwpoort1600 said:

·          I noticed that the magnetic couplers of the locomotive designed by jokey02 are attached to the locomotive body, and not to the bogies. While this is the same as in the original (and as I understand one main reason why I run much better then e.g. the NS 1100), I have not much seen this at Lego/brick-built locomotives. Would I need to change this, or is this all right as long as the pivot point of the bogie is not too far away from the coupler? What is then considered ‘not too far away’, or does that also depend highly on the wagons the locomotive will be pulling?

It all depends on how long your equipment is and what size curves. If you are using normal lego curves (R40) you'll probably need couplers on the bogies, if you are using wide radius curves you might be able to do couplers on the cars. Best way to find out is to MOC up a few flat cars of the desired lengths and see if they work through all of the switches and curves you want the train to work through. The flatcars will let you quickly prototype ideas without the risk of having to massively rebuild a MOC. Then once you get it, you can keep the geometry as you move to the actual cars and locos.

[Stereo]

The middle axle is the ideal one to move sideways but if it's inconvenient for other reasons (motorization,...) you could have fixed middle and one end, and let the other end slide.  Doing some math, if the 14 stud beam is being used full length and the axles are 6 studs apart, on R88 the middle axle is 0.21 studs offset from the ends. On R40 it's 0.45 studs thus being able to use a 3 stud wide chassis.  Meanwhile if one of the end axles slides, then on R88 it's 0.4 studs offset (still able to use 3 wide chassis) or on R40 it's 0.89 studs offset, would have to go to 2 wide... but of course R40 is very tight for that size engine.  Actual design depends where you plan to attach side decorations, it could just be a train motor with a 2x6 stud plate sticking off one end with technic beams under it.

[SD100]

I'll take pics later, but for an SD40 MOC I've been working on I put the 3rd axle on a pivot, braced by part no. 45590. (https://www.bricklink.com/v2/catalog/catalogitem.page?P=45590&name=Technic, Axle Connector Double - Flexible Rubber&category=[Technic, Connector]#T=C)

I have yet to have an issue with truck steering with it.

SD

[Hod Carrier]

I have used bogies of this size and design with some success on my CIE CC1 locomotive, and that can run on R40 curves (Click - Loco appears about halfway through).

I used 14L Technic bricks (#32018) the same as the design you downloaded and had blind wheels on stub axles in the middle. For these, I used a round plate with a cross hole (#4032) and a round tile with hole (#15535) on a 2L Technic axle (#32062) to allow for free rotation, as these wheels are not driven. This gets around the need to leave space for a sliding axle to move from side to side in the bogie and the side frames and also allows space for a drive shaft to pass down the middle of the bogie to link the first and third axles for drive through bevel gears.

How you power the loco will depend on what sort of performance you want. The fastest motor is the train motor followed by the Technic M, L and then XL as the slowest. You can always gear the Technic motors up for a bit more speed, but that will require some space inside the loco or bogies to accommodate it. If you're feeling very brave you can still use the train motor with Technic bogies to get the look and speed you want, but it's not an easy technique. Basically you would need to mount the train motor on it's side inside the body of the loco and use one of it's axle holes as your bogie pivot and drive input, but that requires careful placement to ensure that the axle hole is central and exactly where you want it. I think most builders would recommend that you put the couplers on the bogies and not the body due to the large amount of movement possible between vehicles. I know that I would.

I always design digitally first and then build once I am happy with how everything fits. It helps to keep the costs low because you only buy the parts you actually need rather than needing to have loads of extras that may not be used. This may not be an issue if you have loads of parts already, but I don't have that luxury. Ultimately it's up to you to find what works best for you. Just be a bit careful with Stud.io as it can allow some overlap between parts before flagging a collision.

[Selander]

If you "insist" having a 3-axle bogie, I lean towards your option #4, meaning a std 2-axle train motor + a trailing single axle.

There are many benefits using std train motors:1) Reliability (you avoid chasing gearing parts that falls off, or crushed gears) 2) Compactness (plus simple plug&play installation). 3) Speed. 4) Cost.

Some objects that technic motors + lower gearing means more strength (pulling power), but my personal experience is that a locomotive with 2x train motors gives enough pulling strength and speed for most applications.

My preferred set-up for a working horse locomotive nowadays is: Powered Up 4ch technic hub + 2x train motors+ 2x Led:s.

[dtomsen]

My own favorite solution for more modern locomotives utilizing blind drivers for three-axle bogies which easily navigates all curves and switches down to R40.

Very reliable but gears and axles will inevitable be worn down over time with heavy event duty and have to be checked and replaced. Just basic maintenance 101 

With standard train wheels and black hockey puck as the blind driver:
(2 x 2 round tile with open stud and 1 x 1 round tile placed on top on it can be used instead as the blind driver).



Link

Compared to slightly larger MS train wheels:



Link

In real live action video pulling six passenger wagons weighing approx. 1 kg each with 2 x Technic L-motors, 5:3 upgearing (for more speed) and 1 x BuWizz 2.0 battery box at near max. normal speed, that's 7,2v.
The BuWizz delivers up to 9,2v on fast speed and up to 11,2v on ludicrous speed.

Each L-motor block:



Link

Edited May 9, 2024 by dtomsen

[zephyr1934]

Oh, that's another thing I did. I made brick built trucks with three rigid axles, no flexing no bending no sliding. For the outer two wheels I replaced the traction bands with thicker O-rings, then on the middle axle I left the normal traction bands. That half plate of extra lift allowed the middle axle to clear switches and R40 curves without problems.

But if you were building long trucks, I'd recommend the train motor plus pivoting 3rd axle that others have suggested.

[slagbijnieuwpoort1600]

Thanks for all the help! It took me some time to process all the advise and work a bit further (and I'm still quite slow in digitally building). I decided that a blind driver in the middle would be a good balance between ambition and realism for me. I saw quite some 4 x 4 technic bricks with hollow centers in the different bogies from e.g. @dtomson, and I guess this will increase the strength of the bogie by using these instead of 2 1 x 14 technic bricks? I therefore extended the bogies a bit so that it now looks like this from beneath:
I didn't replace the wheels on the middle axis yet, because I'm still undecided on using the Hockey Puck, a round tile + plate or even move to M-wheels that UrbanErwin used as well.
At the DSB Litra MZ III bogies I see that a 4 x 4 turntable is used instead of making everything flat. This is probably to increase the strength of the connection between the bogie and the body, right? I think I'll apply that too.

On 5/8/2024 at 3:25 AM, Hod Carrier said:

How you power the loco will depend on what sort of performance you want. The fastest motor is the train motor followed by the Technic M, L and then XL as the slowest. You can always gear the Technic motors up for a bit more speed, but that will require some space inside the loco or bogies to accommodate it. If you're feeling very brave you can still use the train motor with Technic bogies to get the look and speed you want, but it's not an easy technique.

Regarding the motors, according to https://www.philohome.com/motors/motorcomp.htm the XL motor is a bit more efficient than the train motor, but I'm guessing that this is mostly because no gears are involved, so you loose this (and maybe even a bit more) when adding the necessary gears to an XL motor? I would however also like it to be able to move a bit slower then with the train motor, and with a higher torque the speed stays probably also more constant in curves and when climbing a slight slope? With the battery I used (a 9,4V Zenter battery) in my V100 with train motors the locomotive is even a bit too fast for my taste. With M-wheels the speed would be even higher. A train motor on the side would still probably fit in the model (the locomotive is quite large and the sides are relatively simple 1-wide bricks), but aren't you then loosing on performance because only one of the two axle holes is used?
 

On 5/7/2024 at 11:09 PM, zephyr1934 said:

It all depends on how long your equipment is and what size curves. If you are using normal lego curves (R40) you'll probably need couplers on the bogies, if you are using wide radius curves you might be able to do couplers on the cars. Best way to find out is to MOC up a few flat cars of the desired lengths and see if they work through all of the switches and curves you want the train to work through. The flatcars will let you quickly prototype ideas without the risk of having to massively rebuild a MOC. Then once you get it, you can keep the geometry as you move to the actual cars and locos.

I already have the carriages so I will start experimenting with a flatcar as locomotive whether it is possible to connect the couplers to the body. It will probably then also help to put the technic bar that connects the body + motor and the bogies as much to the front (or rear in case of the second bogie) as possible, am I right? I was already trying to do that in the current design shown above, but I could move the bar one stud further to the right but then I cannot keep the 4x4 technic brick with hollow centre at that location. Thanks again for all the help!

[LEGO Train 12 Volts]

For my Nohab I adopted this solution (inconceivable for purists) but all in all compact (12 stud long carriage and central axis with metal axle free to move left and right during curves)

The traction system is the same suggested by Tomsen:

On 5/8/2024 at 12:47 PM, dtomsen said:

 

Edited June 23, 2024 by LEGO Train 12 Volts

[zephyr1934]

On 6/20/2024 at 5:05 PM, slagbijnieuwpoort1600 said:

I already have the carriages so I will start experimenting with a flatcar as locomotive whether it is possible to connect the couplers to the body. It will probably then also help to put the technic bar that connects the body + motor and the bogies as much to the front (or rear in case of the second bogie) as possible, am I right? I was already trying to do that in the current design shown above, but I could move the bar one stud further to the right but then I cannot keep the 4x4 technic brick with hollow centre at that location. Thanks again for all the help!

Yes, testing the mechanicals is critical if you are pushing the limits. That, and larger radius curves are your friends.

Meanwhile, your truck is starting to get long. If you plan to run on tight curves (R40) you should be careful to also test a prototype of the truck to make sure it does not bind in the curves or try to climb the rails at the joints on a curve. When you have the option, mounting the motor so it tries to turn the truck to the left is probably slightly better than turning to the right because the right rail has a slight indent, as per below, from  my clockwork article from Railbricks 7. I think this is more an issue with 9v track than the all plastic track, but something to keep in mind. With normal wheel spacing and normal wheels it is almost never a problem. With large wheels or otherwise unusual wheels, it can be a problem because it provides an opportunity for a flange to catch, climb the rail, and cause a derailment.

 

[slagbijnieuwpoort1600]

On 6/21/2024 at 10:36 PM, LEGO Train 12 Volts said:

For my Nohab I adopted this solution (inconceivable for purists) but all in all compact (12 stud long carriage and central axis with metal axle free to move left and right during curves)

I'm sorry but I don't understand how this works: how can the wheels on the middle metal axis move left and right? And how does the metal axis not interfere with the vertical and horizontal technic bars, does the metal axle just fit under the gear?
And regarding that is not for purist: that is mostly because you cut several 'Train Motor Decorative Side'-parts into two? That is not strictly necessary for this solution, am I right?

Regarding the traction system, if I'm correctly a L-pf motor runs at 272 rpm  and with a torque of 6.48 N.cm at 9V (from philo), so this means with a 5:3 up-gear (and with assuming no loss of efficiency) a 453 rpm and a torque of 3,88, which makes it still much stronger but slower then a train motor when using S-wheels, am I right? When using S-wheels it will have an speed of around 1,5 km/g, when using M-wheels it is a bit more respectable at 2,1 km/h but still quite slow. Or am I missing something? Ideally I would be able to reach ca 3 km/h because in real life the maximum speed in service of this locomotive was 130 km/h. If this is not feasible I could live with a bit slower speeds, but it seems that I have enough room for e.g. another 5:3 up-gear, which would definitely help in getting more realistic speeds. Or would you recommend increasing the voltage or using a non Lego 'enhanced motor' to achieve this?

On 6/23/2024 at 7:39 AM, zephyr1934 said:

Meanwhile, your truck is starting to get long

You are talking about the distance between the two axles, right, just like in the article below. I didn't increase that, only extended the bogie further forwards and backwards. So they are still 13 studs apart, which indeed is a bit suspicious but seems ok with S-wheels as long I'm not driving to fast. I will not be using 9V-tracks, and the largest wheelsize I'm considering is M so then it wouldn't be that much of a problem probably?

A more radical way to solve this is to put the blind drivers at the outermost axis, the other two will then be 7 studs apart which is perfectly fine. Another advantage would the be that the technic bar that forms the turning point of the bogies/trunks can be placed much closer to the front/rear of the locomotive, which then improves the possibility of connecting the couplers to the body instead of the bogies. My guess is that the disadvantages are that quite a large part of the bogies (the part towards the centre) is not under the body any more in tight curves, and that the blind driver can be seen from the front of the locomotive. Quite some things to test out.
 

By the way, the link http://railbricks.com/magazine/issue-7/ doesn't seem to work anymore, but I found the article at https://brickmodelrailroader.com/wp-content/uploads/railbricks/railbricks_7-print.pdf I get the point of the article, but this would mean that my (otherwise symmetric locomotive) would get a clear front and backside, am I right?

[LEGO Train 12 Volts]

21 hours ago, slagbijnieuwpoort1600 said:

I'm sorry but I don't understand how this works: how can the wheels on the middle metal axis move left and right? And how does the metal axis not interfere with the vertical and horizontal technic bars, does the metal axle just fit under the gear?
And regarding that is not for purist: that is mostly because you cut several 'Train Motor Decorative Side'-parts into two?

First of all the central metal axis is put inside two Technic Pin 1/2 without Friction Ridges ...the pins are facing with the protruding part facing inwards and not towards the wheels.
The metal axis thus does not wobble inside the hole of the technical brick but is kept centered inside the pin.
The metal axle passes under the drive gear without colliding
The fact that the axle is metal, however, leaves a certain freedom for the central wheels to slide left and right when the trolley faces curves...don't think of an excursion greater than 2/3 mm but this allows the trolley to slide fluid.

...and regarding the solution not for purists the answer is "YES" due to the cuts on the decorative sides

Edited June 26, 2024 by LEGO Train 12 Volts

[aFinePlan]

On 6/25/2024 at 5:37 PM, slagbijnieuwpoort1600 said:

A more radical way to solve this is to put the blind drivers at the outermost axis, the other two will then be 7 studs apart which is perfectly fine. Another advantage would the be that the technic bar that forms the turning point of the bogies/trunks can be placed much closer to the front/rear of the locomotive, which then improves the possibility of connecting the couplers to the body instead of the bogies. My guess is that the disadvantages are that quite a large part of the bogies (the part towards the centre) is not under the body any more in tight curves, and that the blind driver can be seen from the front of the locomotive.

Found this searching for ideas for my own application, is there a solution to the leading blind driver with a powered center & rear driver. The three bevel gears top/left or right/rear on the center axel would mesh agains each other I think. Assuming that my center axel is directly below the top driving gear the only way I can think to do it would be to use the 20 tooth bevel gear on top but then becomes hard to stabilize the center axel. The only other thing that crossed my mind was to drive the center axel with the 12 tooth bevel and then transfer power to the rear axel using a rubber band and bushing on the center axel and transfer the power through the rubber band to a bushing on the rear axel, but unsure how much slipping there would be on the band from center to rear. Any ideas?

Edited June 27, 2024 by aFinePlan

[Stereo]

If you have some extra vertical space, you can use a double-sided 12T bevel on the vertical axle, and mesh it into a double sided 20T bevel behind it, so that one can go to the 12T for the third axle.  Since it just goes 12-20-12 there's no gear reduction and both axles end up at the same speed.  A bit annoying to fit the 20T though, it's wide enough you can't have it in between 4 stud wide beams.  12-12-12 technically possible but difficult to mount the middle one since it needs half stud offset vertical holes.

Edited June 27, 2024 by Stereo