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  • 4 years later...
Posted

I tried a couple of ideas posted here but they tended to break under significant load. I decided to try a slightly different approach in which there is no bulky rotating parts.

uc?export=view&id=1bERPGJAhotIiUAEliFov0

One output of the diffs is sent to the wheels while the other is sent to the opposite diff via a pair of worm gears similar to the ones that are located in the rotating part of the "normal" torsen diff. As in the regular torsen, the right hand outputs of the diffs rotate with the speed that is difference between drive shaft speed and half axle speed. As a result, it allows smooth turns but locks the wheels together when one of them loses traction.

As you can see in the picture, the forces that act on the worm gear part as quite large (the structure that holds the worm gears in place bent) so I need to make it stronger for real usage. I'll probably also replace the fragile 8-tooth gears with 24s (for the worm gears) and 16s. The fact that the structure does not have to rotate allows me to built is as robust as I want/need.

Because the whole thing is too bulky to fit in a classic live axle design I plan to built a model of Mowag Duro which uses DeDion type suspension in which the differential is bolted to the chassis. Real Duros have also a torsen center diff. Handling the torque there would be quite a challenge. Wish me luck!

Posted (edited)

That's extremely interesting, great idea!  Potentially you could increase the number of 8t gears, to spread the load.

A problem with replacing the 8s with 24s is that it will triple the torque on those axles.

 

Edited by aeh5040
Posted

Now this is something worth reviving an old thread for. I thought about something like moving the locking mechanism out of the diff, and this does exactly that. However, your real enemy is torque, and figuring out how to manage that.

Posted

Does anyone know if two of the new 1L worm gears will mesh with each other?  The spacing would need to be weird, but this could reduce the number of high torque components. 

I can't check - separated from most of my collection by the virus :cry2:

Posted

Barely. Distance would be 1.5 studs center-to-center. Additionally lego worm gears don't lend themselves to being back-driven very well; they tend to move on their axles instead.

Maybe, instead of using worm gears, it might be possible to use normal gears on blue friction axle-pins instead?

Posted
7 hours ago, pleegwat said:

Barely. Distance would be 1.5 studs center-to-center. Additionally lego worm gears don't lend themselves to being back-driven very well; they tend to move on their axles instead.

Maybe, instead of using worm gears, it might be possible to use normal gears on blue friction axle-pins instead?

I don't think so - that's not how the torsen diff works.  The worms with their inability to be back driven are the crucial aspect.  They do of course want to slide on their axles - good bracing is essential.

Posted (edited)
1 hour ago, Bluehose said:

Another way.

Still stiff yet more compact.

20200326_110058.jpg

 

 

Great idea! What about not using diffs at all?

Edited by Zerobricks
Posted
Just now, Bluehose said:

Without diff it will no longer be a torsen

You could use one central diff for left and right side drive with the worms and 20 tooth gear linking them.

Posted (edited)

Indeed the last configuration don't work, I did try to understand what Zerobricks would mean ; I don't know what is the configuration he is talking about

Edited by Bluehose
  • 2 months later...
  • 6 months later...
Posted (edited)
14 hours ago, LegoEmbodiment said:

 

I'll have to try that! It looks both stronger and less bulky than many previous attempts!

Edited by Milan
Removed quoted video.

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