[CONCEPT] Double Torque Tube Suspension

[Zerobricks]

I got this idea yesterday and decided to build it.

Its an improvmement of a classical torque tube suspension, but now it uses 2 torque tubes to form two half axles which are connected to each other via a turntable:

To keep the half-axles from bending away there's a lower linkage made out of 5L suspension arms and some beams:

So what's the difference btween this and classical single torque tube?

Lets start with advantages:

- No need for links or panhrads to keep the axle in place

- Now each axle can have an independent drive, which cancel each other's torque therebye elimenating torque flex

- Or you can use one ball joint for drive an dother for steering

- Can carry much more torque

And there are also some disadvantages:

- Less flexible, maximum angle this setup can bend to is some 30 degrees

- Steering is a bit more complicated, since the axles pivot in the center, you need some ball joints and links

- Takes more space

But you can even expand the concept to use three torque tubes.

Now the side ones can carry power while the center one supports the steering system:

This is just a concept for now, but I might try it in a realy model just to see how well it will work.

What do you guys think? If possible try to build one your own and give me some feedback.

Edited March 17, 2016 by Zblj

[bj51]

Wouldn't this bend some parts under load ? You're forcing the frames held together by the turntable to stay together with the ball joints.

[JJ2]

Nice idea, I would build this but I lack the mini turntables, I need to buy some.

[Technic Jim]

I have just build this suspension module and I find it very cool. It has good up and down travel and alright twisting degrees. I changed it slightly as follows:

• I didn't add the lower linkage because I found that it reduced twisting
  
• I added shocks in a similar way that you would for single tube floating axle
  
• I added portal hubs and an overall gear reduction of 5.001:1
  

Pictures:

[jgw]

I am not an engineer, so correct me if I'm wrong, but if you rotate the turnable 90° lengthwise, then it fits between the O-frames, wouldn't that improve the pivot point? It would also give the opportunity to couple the drive-axle, but that would deny your idea a little I see

[Zerobricks]

I am not an engineer, so correct me if I'm wrong, but if you rotate the turnable 90° lengthwise, then it fits between the O-frames, wouldn't that improve the pivot point? It would also give the opportunity to couple the drive-axle, but that would deny your idea a little I see

Yes, sure you can do that, it was my original idea, but the conenction will be a bit weaker since you need some connectors between frames and the turntable. And this axle is meant for independent left/right wheel drive since it allows you vehicle to steer much better than if wheels are hard coupled.

[jgw]

Yes, sure you can do that, it was my original idea, but the conenction will be a bit weaker since you need some connectors between frames and the turntable. And this axle is meant for independent left/right wheel drive since it allows you vehicle to steer much better than if wheels are hard coupled.

Jep, I expexted it to be so. I just had that idea but I forgot ZBLJ is the master of idea's ;-)

[MSc Shobaki]

Being an M.Sc in Mechanical engineering, my question may sound harsh but anyway: What is the point of having two frames with torque ball joints? Here are some thoughts of why I'm not impressed

1. You lose the whole function of the ball joints since their job in your design will only be to move up and down in the center of the u-joints. As long as the ball joints move up and down, it is fine.

2. Adding a second torque ball frame like you have done will result in locking the whole rear axle from sideways and rotational movement. As you demonstrate its damping capabilities, you are also introducing high stresses in the parts that hold together the two frames, in your case the turntable. Simple mechanics.

3. The only thing that you accomplished with your design now is simply a stiff live axle that moves up and down, any attempt to move it sideways/rotate will only be due to the parts flexibility/slack. Start over.

Hope that take this as a constructive critisism from an engineers point of view :)

[Zerobricks]

Being an M.Sc in Mechanical engineering, my question may sound harsh but anyway: What is the point of having two frames with torque ball joints? Here are some thoughts of why I'm not impressed

1. You lose the whole function of the ball joints since their job in your design will only be to move up and down in the center of the u-joints. As long as the ball joints move up and down, it is fine.

2. Adding a second torque ball frame like you have done will result in locking the whole rear axle from sideways and rotational movement. As you demonstrate its damping capabilities, you are also introducing high stresses in the parts that hold together the two frames, in your case the turntable. Simple mechanics.

3. The only thing that you accomplished with your design now is simply a stiff live axle that moves up and down, any attempt to move it sideways/rotate will only be due to the parts flexibility/slack. Start over.

Hope that take this as a constructive critisism from an engineers point of view :)

Thank your for your opinion. I know that in an ideal world where everything is stiff and has no slack this might not work, but:

1. Lego pieces have enough play for the axle to swiwel 30 degrees with no problems

2. Again turntable has enough slack to allow the frames to go slightly together when suspension is titled. It even works in LDD and we all know how unforgiving LDD's physics is

3. Try buildling and than criticise plase.

[MSc Shobaki]

Thank your for your opinion. I know that in an ideal world where everything is stiff and has no slack this might not work, but:

1. Lego pieces have enough play for the axle to swiwel 30 degrees with no problems

2. Again turntable has enough slack to allow the frames to go slightly together when suspension is titled. It even works in LDD and we all know how unforgiving LDD's physics is

3. Try buildling and than criticise plase.

Try to look at my critisism in a positive and educational way. What makes a LEGO-moc interesting? The complexity without sacrificing stiffness to deliver certain functions. In other words, I don't find your concept to be interesting as you have an idea which relies on the slack/play in the parts. To me, it sounds like you need to develop your idea further. Even though you have many ideas to implement, you need to develop them further.

Now I might sound negative and harsh but I just want you to aim higher. Instead of just relying on slack or building without respect to mechanics, why don't you build sturdy complex designs that have proper stiffness and deliver the functions that you want?

Personally, I'm not a fan of using parts to things they are not designed for nor integrating the parts to deliver a function that would introduce stress which in turn results in breaking.

[Captainowie]

I would consider that designing a suspension system that relies on the slack between parts is potentially more impressive than a sturdy one. It's taking some secondary effect of the LEGO system that is mostly regarded as a negative, and turning it into a positive. I claim that it's similar to someone designing some mechanism that relies on the non-linearity of a U-joint.

In fact, it's exactly the same concept, albeit in the opposite direction, as those cheese slope mosaics that you can get by shoving the small bits into a fixed frame and using the tension to hold it all together.

[Joefraser]

Nice system and great reply Zblj, I love the look of it and as said above taking a detrimental feature of lego (the slack) and utilising it in its design is more impressive than using your education as an introduction.

I don't have an Msc in mechanical engineering, but does that matter in the real world of lego building? I plan on creating in LDD to try and incorporate it into my project... it may be a touch too wide though and I don't have all the real world parts currently- though my building buddy does!

Thanks for sharing :).

[Moz]

I don't have an Msc in mechanical engineering, but does that matter in the real world of lego building?

I threw together a quick copy of the axle/suspension and it seems pretty reasonable. There's enough space to add extra gearing or twiddling, and it's an easy way to get two driven axles into a suspended axle. I don't really see the problem.

In a way it's more elegant than my "keep the lowloader straight using string" design that I came up with to avoid the saggy look you get with long Lego beams (like the "tow haul" trailer in the current list). This is all Lego, and the attachments even meet the LGM rules AFAIK.

Generally an argument from authority is the posters way of saying "I don't have any actual reasons, but I think..." If they had reasons they'd post those instead, and people would respect them for the quality of their argument rather than the size of their embellishments. I still regret that I didn't change universities between my degrees so I could legitimately call myself "MOZ, BE ME" in these situations, rather than "Moz, ME BA" which isn't nearly as amusing. Is there a degree that's just "A" and outranks an ME? Coz then I could be "Moz, A ME BA" (amoeba).

[MSc Shobaki]

I threw together a quick copy of the axle/suspension and it seems pretty reasonable. There's enough space to add extra gearing or twiddling, and it's an easy way to get two driven axles into a suspended axle. I don't really see the problem.

In a way it's more elegant than my "keep the lowloader straight using string" design that I came up with to avoid the saggy look you get with long Lego beams (like the "tow haul" trailer in the current list). This is all Lego, and the attachments even meet the LGM rules AFAIK.

Generally an argument from authority is the posters way of saying "I don't have any actual reasons, but I think..." If they had reasons they'd post those instead, and people would respect them for the quality of their argument rather than the size of their embellishments. I still regret that I didn't change universities between my degrees so I could legitimately call myself "MOZ, BE ME" in these situations, rather than "Moz, ME BA" which isn't nearly as amusing. Is there a degree that's just "A" and outranks an ME? Coz then I could be "Moz, A ME BA" (amoeba).

Like I said, my intention with my post was to Zblj to take it as constructive critisism from my engineers point of view. I did not call him nothing or even disrespected him for that matter. If Zblj wants to see the whole system as a toy or needs to base his work on slacky systems, that's up to him. My goal was to inform him about how his idea would not work in real life if we look at its mechanics. Even though you've built in with real lego parts, you are missing the big picture of what my goal was.

[Lipko]

Like I said, my intention with my post was to Zblj to take it as constructive critisism from my engineers point of view. I did not call him nothing or even disrespected him for that matter. If Zblj wants to see the whole system as a toy or needs to base his work on slacky systems, that's up to him. My goal was to inform him about how his idea would not work in real life if we look at its mechanics. Even though you've built in with real lego parts, you are missing the big picture of what my goal was.

I have a MsC in engineering too, and I don't fully agree with you, though I agree with principles (like not introducing stress and the others). But I think the slack in Lego is considerable, and even real machines rely on "slack" in a way that Lego can't do: rubber springs and rubber joints all around.

Even Lego designers "legalized" this twisting slack-reliant suspension technique in the Mercedes Acors model: the front suspension is something I would have never considered to be legal (I used a very similar suspension in my hot rod and I wasn't too confident in it's legality, even though it had 18 long trailing arms instead of 5, as in the Acors).

[deehtha]

I think the real engineering feat is taking a weakness in the part and using it a strength.

Lego pieces have a ton of slack in them, making most suspension and steering solutions sloppy. And it is t something you can engineer away. Why not try to find a way to use it. It is no different than the torsion beam suspensions found on many vehicles. Using the weakness of the material (the elasticity of the metal) and turning it into something functional

[Victor Imaginator]

Same concept, but without parts slack. Sad, but it's whole long day at the work, so i can't just build and test it right now.

edit: By the way, turntable works incredibly fine. Builded, tested, enjoyed)

Edited March 20, 2016 by Victor Imaginator

[Zerobricks]

Same concept, but without parts slack. Sad, but it's whole long day at the work, so i can't just build and test it right now.

edit: By the way, turntable works incredibly fine. Builded, tested, enjoyed)

That looks like a good solution, gonna give it a go.

[nerdsforprez]

Like I said, my intention with my post was to Zblj to take it as constructive critisism from my engineers point of view. I did not call him nothing or even disrespected him for that matter. If Zblj wants to see the whole system as a toy or needs to base his work on slacky systems, that's up to him. My goal was to inform him about how his idea would not work in real life if we look at its mechanics. Even though you've built in with real lego parts, you are missing the big picture of what my goal was.

@MSc Shobaki - I think perhaps your response to Zblj could have been taken better if a few things would ave been considered:

- Beginning a post with your degree, although logically - speaking makes sense, from a social standpoint probably is not the best idea. There are many on this site with advanced degrees, and some with advanced degrees and experience that surpass even yours. Not a good tree to bark up. In addition, it places people on the defense right away.

- You even admit in your post that your opinion carries more weight when considered from a certain POV. A strict Engineer's POV. That is excellent, and perhaps true, but it is still based from a certain POV. However, you make your remarks as the definitive voice on the matter. Many bring their academic book-knowledge to the table on the forum here.... which is great and helpful. But we all know that academic, book-knowledge, doesn't always apply. Know the differences and potential conflicts that can arise when strict academic principles are applied to real-life scenarios. Rarely are there such definitive answers to problems as such poised in this post, rather answers according to a certain POV; but a POV that perhaps not everyone is ascribing to.

Overall your message sounds like it was given with the best of intentions. Keep giving your opinions because it sounds like you have much to offer. IMO, just perhaps consider the points described above.

[powder12321]

I dont have the ball joint so i cant test it but idea is good and strong

[zux]

The concept won't work well with ball joint as it would be too stiff. Pole reverser handles will be just half stud/beam into Axle Connector 2 x 3 with Ball Socket, so I suspect they won't keep very well.

[JJ2]

I had am idea on how to improve the idea so I built it in LDD. I made it where the mini turntable was centered on the 5x7 frames making it less reliant on part slack and then I made a rough spring mount, yellow goes on yellow.

DOWNLOAD

If you build the improvement could you post some pics?

[Victor Imaginator]

The concept won't work well with ball joint as it would be too stiff. Pole reverser handles will be just half stud/beam into Axle Connector 2 x 3 with Ball Socket, so I suspect they won't keep very well.

It's just quick sketch of an idea. I've tested something yesterday, and it's more complicated, than it looks at pictures. Zblj's first idea still working better in any cases)

[MSc Shobaki]

@MSc Shobaki - I think perhaps your response to Zblj could have been taken better if a few things would ave been considered:

- Beginning a post with your degree, although logically - speaking makes sense, from a social standpoint probably is not the best idea. There are many on this site with advanced degrees, and some with advanced degrees and experience that surpass even yours. Not a good tree to bark up. In addition, it places people on the defense right away.

- You even admit in your post that your opinion carries more weight when considered from a certain POV. A strict Engineer's POV. That is excellent, and perhaps true, but it is still based from a certain POV. However, you make your remarks as the definitive voice on the matter. Many bring their academic book-knowledge to the table on the forum here.... which is great and helpful. But we all know that academic, book-knowledge, doesn't always apply. Know the differences and potential conflicts that can arise when strict academic principles are applied to real-life scenarios. Rarely are there such definitive answers to problems as such poised in this post, rather answers according to a certain POV; but a POV that perhaps not everyone is ascribing to.

Overall your message sounds like it was given with the best of intentions. Keep giving your opinions because it sounds like you have much to offer. IMO, just perhaps consider the points described above.

That my dear is the best reply I have seen this far. Like you said, my comments were only made with the best intention. I can admit that the whole thing with my degree may have sounded like "IN YOUR FACE" and makes people feel small. My intentions were to encourage Zblj to develop the idea further, and I backed up my comments with knowledge from my degree and experience from real-life work. Facts and experience. But I never wanted to come out as rude or anything.

I haven't posted much here on EB, therefore I dont think I have introduced myself. I will try to post a new thread with some info about me and my current WIP

[nerdsforprez]

:thumbup: Wonderful. Looking forward to your new post.