Motorized 5L bogie

[TrainDragon]

I'm trying to come up with a short set of wheels that I can motorize.  This is the best I've been able to come up with so far.

The white shaft with the black gear on it lead to the motor, which is in the carriage.

I've built it in real life and it works, but...

Edit: I can't figure out how to embed the image, sorry, so here's a link: https://imgur.com/a/vJf9NOn

The problem is, the white axle/black gear, while firmly affixed to the frame, are not permanently attached to the bogie.  So if I pick up the car, the wheels remain on the track.

Does anyone have a better idea for a powered wheel-set of this length?

 

Edited November 12, 2018 by TrainDragon
fixing image link

[supertruper1988]

You need a more encapsulating build. Under any stress or pulling this thing will go BOOM. 

This is an interesting problem. Maybe I will look into it some if I have some time this week. 

[Rijkvv]

I do wonder how powered short bogies will behave on tracks. Due to the torque they tend to turn, and in combination with aftermarket o-rings it was enough to derail my test vehicle.

[pagicence]

The only thing I came up with is this.

But I don't know how that DBG technic piece will hold because it's not fixed, and it will move causing all kinds of gear grinding. But it's something to think about. Or are you set only on technic pieces?

Edited November 13, 2018 by pagicence

[Hod Carrier]

@pagicence I think you're close to a solution. You could swap the 1x6 Technic bricks for the sides for some 1x2 Technic bricks braced with 1x6 plates. That way you can have round holes for the axles and a cross hole each side to secure the DBG part together with some half bushes to prevent it sliding side-to-side.

Will mock something up later on LDD, but I'm away from my computer at the moment.

[Daedalus304]

I made this a few years back, and it's very strong. Basically you build around the motor so that the whole motor works as a pivot. The outermost 5-L Technic half lift arm should actually be this part: http://www.bricklink.com/catalogItem.asp?P=2711

With a little tinkering you can use other motors instead of an XL-Motor if you really want.

This was actually a derivative of a motor bogie used by BMW_Indy in either his Wild West or Circus Train using an M-motor, which was itself a derivative of Space2310's version which was narrow gauge! So it's pretty well-traveled design.

 

[pagicence]

@Hod Carrier is this something like what you had in mind?

We can always put more plates on top and make it stronger if needed, but my question is about bottom red plates. How much are they really needed to keep the LBG technic brick from falling out, or can we do without them? I have no way of really testing this.

@Daedalus304 that is actually an awesome solution. I really like it. And, like you said, "with some tinkering" I think it can be use without the motor on it. BTW I didn't even know that piece 2711 existed.

@TrainDragon how are you liking solutions so far?

Edited November 13, 2018 by pagicence

[Daedalus304]

1 hour ago, pagicence said:

@Hod Carrier is this something like what you had in mind?

 

We can always put more plates on top and make it stronger if needed, but my question is about bottom red plates. How much are they really needed to keep the LBG technic brick from falling out, or can we do without them? I have no way of really testing this.

@Daedalus304 that is actually an awesome solution. I really like it. And, like you said, "with some tinkering" I think it can be used without the motor on it. BTW I didn't even know that piece 2711 existed.

 

@TrainDragon how are you liking solutions so far?

The red plates on the bottom might not be necessary under light loads, but I've always liked to fortify my gear trains as much as possible personally. One thing to note is that with plates under the technic bricks like that, you're not going to be able to make it past switches or crossovers without swapping out the stock traction bands for some thicker O-Rings to give you an extra mm or two of height. Of course, you get better traction that way too, so it could be seen as a win all around. :D

And yeah, 2711 is a really awesome piece that hasn't been made in quite a while. Very useful in some situations though!

[TrainDragon]

Wow, there are some really fantastic suggestions here!  @Daedalus204, I think I actually have some 2711's in my collection somewhere.  I hadn't considered using that piece, great idea.  That DBG piece @pagicence looks like Technic, Axle and Pin Connector Hub with 2 Axles...  You're right, that piece would be great for something like this.  I'll have to add that to my bricklink Wanted list.  I'll be tinkering with these ideas for sure.

[Hod Carrier]

@pagicence Yes, very much like that.

I’ve not tested this set-up either, but I agree with @Daedalus304 that plates added to the bottom will create problem with clearing the rail. How strong the bogie needs to be will depend largely on how much power you’re trying to transmit and how much weight you want to move. There is a risk that the centre section may pop out in use as this design is not going to be anywhere near as strong as the all Technic bogie posted by @Daedalus304.

[TrainDragon]

I was mistaken about having 2711, what I have is the similar but less useful piece without the pin holes at the ends.  Oh well.

I did find a couple of 27940's to experiment with.  Another source of inspiration was this creation of @Hod Carrier's that I found while searching for @Space2310's design, mentioned above (which sadly seems to have been deleted):

 In fact, the black piece he's using there outside the wheels is the piece I mistook for 2711 at first.

Anyway, here are a few more options I came up with based on that:

They both flex more than I'd like, unfortunately.  The technic thin liftarms in the second could probably be replaced with 2711 to make it a lot sturdier.  I bricklinked a couple today, so hopefully next week I'll be able to try it.

I built @pagicence's suggestion in physical bricks to play around with.  Due to the technic hole not really being centered in the brick, if you flip it upside down, you can use a tile piece on the studs-side without causing any clearance issues.  I measured it against a standard Train Motor and it actually has the exact same distance from axle to "bottom".  It's obviously more rigid than my technic-based experiments, but the magic central axis there still has a surprising amount of flex to it, which lets the gears skip when overloaded (though only in one direction, surprisingly).  Not sure there is any reasonable fix for that.

 

[Hod Carrier]

The gears are skipping when overloaded because the vertical shaft that brings the power down from the motor will spin the entire motor bogie round and round if the bogie is not contained. It's only the track and the body of the train that prevents this from happening and causes the turning motion to be transmitted to the central driveshaft and from there to the wheels. However, even when on the track this torque will still be trying to deflect the central shaft to one side or the other. This means that, when travelling in one direction, the gears on the central shaft will be pushed towards the gears on the axles giving a much better mesh, but when it's driving in the opposite direction the gears will be forced away from each other making skipping more likely.

@pagicence's design should be fairly robust. The part holding the central driveshaft should keep everything nicely aligned. If you're experiencing flex I can only assume it's because the two sides of the bogie are not joined sufficiently rigidly. I would recommend swapping the two 1x4 plates for a couple of 2x4 plates and the 2x4 plate with holes for a 2x6 plate with holes orientated along the length of the bogie rather than across it. At present you only have four studs joining each level but making these changes would increase this to eight and should help to reduce flex.

Thanks for spotting the tiny TRAXX. I hadn't noticed that space2310's design has disappeared, but you seem to be right. A quick search on Flickr confirms this. I used it to create a 4-wide scale power bogie, but the restriction on size makes it fairly weak and prone to failure due to the required narrowness. Basically the part you mistook for 2711 holds the central driveshaft but is not actually attached to the rest of the bogie. All that's keeping it together are the ends of the axles nestling inside the stud recesses so it's quite easy for the torque of the motor to push them apart sufficiently for the gears to unmesh or even for the central shaft to drop out completely. However, if you are going to use it for regular 6-wide track you do have some more scope to beef the design up a bit to keep everything aligned.