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I don't know why I'm so fascinated/obsessed with truck axle suspensions, but here's another one for tandem axles, inspired by @Andrea Grazi's suspension on his famous tow truck:

solid-axle3.png

Its weakest point is that the suspension arms are connected to ball pins, which may pop out with excessive force, but from my experience it takes significant effort to do that. For semi-display models, I think it is fine.

With the four yellow springs, load capacity is about 1.2 kg. This can be modified by changing the springs, even putting single springs instead of the double one shown here.

Try it yourself: stud.io file is here, PDF instructions here. Construction is a bit finicky due to the springs being under compression when mounted and everything connecting together in a tight spot.

Feedback welcome! :classic:

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Speaking of tandem axles, I noticed a distinct lack of pendular rear axles for 49.5mm wheels. Here's a design I've been developing for the past few days:

IFHYF62.jpg

7twvBSh.jpg

DkHdItJ.jpg

Soz for the blurry pics, but my iPhone SE camera's an old pile of shit by today's standards.

I was originally trying to go for a proper leaf spring, but I couldn't really figure out anything with common Technic pieces that got the right amount of stiffness with efficient part usage.

The assembly can pitch around 15 degrees either way, and there's enough slack in the leaf-springs-but-not-really-leaf-springs to allow for roughly 10-15 degrees of roll, which I think makes it a perfect tandem axle for light off-road/bumpy gravel. Because of the abundance of tan axle pins, there's also enough slack for a bit of yaw in the assembly, hence the panhard rod. The black 9L bars are to stop the two axles from pulling themselves apart under load.

I'm planning to use it for a logging truck in the Mack Anthem scale.

Edited by Bartybum

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1 hour ago, Bartybum said:

I'm planning to use it for a logging truck in the Mack Anthem scale.

Looks very promising! Although the friction-less-pins always makes me worry for stability. Good idea to counter this with the panhard rod. :-)

For my current (side-)project of an older tractor, I tinkered on a steered, oscillating, non-driven front axle and came up with this:

Vorderachse2.png

Vorderachse1.png

Ackermann-geometry and really good steering angle.

 

On a side note: Can anybody tell me, if the newer CV joints (52730.t1.png) have a better angle ability in contrast to the older one?

Edited by Jundis

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5 minutes ago, Jundis said:

On a side note: Can anybody tell me, if the newer CV joints (52730.t1.png) have a better angle ability in contrast to the older one?

From my testing the older version seems to run better at sharp angles. I’m disappointed in the new version’s binding when spun close to maximum angle.

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13 hours ago, Jundis said:

 

On a side note: can anybody tell me, if the newer CV joints (52730.t1.png) have a better angle ability in contrast to the older one?

 

13 hours ago, TechnicRCRacer said:

From my testing the older version seems to run better at sharp angles. I’m disappointed in the new version’s binding when spun close to maximum angle.

I would say that the new ones have a significantly better maximum angle than the old ones, but it is true that they run a bit rougher right at the limit.

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Here's an idea I just got and simply had to test it.

I discovered the old female CV connector 92906 can mate with the planetary hub's female CV joint!

This allowed me to create something really unique, a portal+planetary hub hybrid:

640x554.png

I had to use a combination of an older 14 tooth gear and a 20 tooth bevel gear in order to transfer the power:

640x696.png

The reason for using half gears instead of normal full gears lies in the way the 92906 mates with the planetary hub, it can't slide in all the way. That's also why the lower attachment point uses a connector in such odd orientation.

640x444.png

This combined hub has several advantages to the old portal hub (92908):

  1. A much higher end gear ratio - 7,71 compared to 3
  2. Closer pivot point - using the rims from Defender/Ferrari the steering pivot can be a stud closer to the wheel
  3. Much stronger driveline - since there are no 8 tooth gears, U joints or axles to bend, the axle can withstand much higher forces
  4. Better gear protection - The gears are much less exposed to debris

Here's a very basic axle setup with a diff lock. Such an axle has a massive 1:18 tooth gear ratio and I think with a bit more work it will be suitable for really massive and heavy (5 kg+) offroad models. Who knows, I may use it to make a proper large scale truck trial Unimog.

640x358.png

Of course I built and tested the hub from real bricks too and I'm planning to shoot a video of the hub assembly shortly, so please stay tuned.

Edited by Zerobricks

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6 hours ago, Zerobricks said:

I discovered the old female CV connector 92906 can mate with the planetary hub's female CV joint!

This is really interesting, as I just had an idea (posted in Efferman's thread that includes another custom part as well) that would require a male CV connector with a 2L axle, almost what you discovered here. Imagine a planetary hub at the end:

400x300.png

It's too bad that it does not go all the way into the hub part, as this use case would require that, I guess this would not fly, the cross connector would be too close, right? I don't have the old CV's female part to test (just ordered a few).

How is the steering angle with that mate with respect to the standard one?

The axle looks really promising by the way.

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11 hours ago, Zerobricks said:

Here's an idea I just got and simply had to test it.

Hi, I also used female CV 92906 to build a test sample, two years ago. But needs to be modified with 92906, I happen to have a lot of broken parts. Your idea is more ingenious. ;)

https://vk.com/video511631021_456239033

 

IMG_7701.jpg

Edited by Milan
Do not quote the whole block of text and pictures, please.

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49 minutes ago, brickless_kiwi said:

The older 14tooth gear are rare and also fragile as glass....

And very expensive, in China. 

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16 hours ago, Zerobricks said:

I discovered the old female CV connector 92906 can mate with the planetary hub's female CV joint!

I gave it a try, and it should be noted that while it mates it will not pivot at all. Or am I doing it wrong?

Edited by pleegwat

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31 minutes ago, pleegwat said:

I gave it a try, and it should be noted that while it mates it will not pivot at all. Or am I doing it wrong?

I think it does not matter for those applications above, as it is fixed in both planes since neither the suspension, nor the steering is implemented through that connection; steering is taken care of the joint above it, suspension by the floating axle into which it is built into. However, it's good to know, that means it would not work for my application, because I wanted to steer through it..

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13 hours ago, brickless_kiwi said:

The older 14tooth gear are rare and also fragile as glass....

They are rare, but it might be able to hold up here simply because of the low torque requirement at that point in the drivetrain. I wouldn't trust it with a hugely powerful/heavy model, though. I imagine double-bevel gears could be swapped in somehow, with the cost of making the axle wider.

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1 hour ago, 2GodBDGlory said:

They are rare, but it might be able to hold up here simply because of the low torque requirement at that point in the drivetrain. I wouldn't trust it with a hugely powerful/heavy model, though. I imagine double-bevel gears could be swapped in somehow, with the cost of making the axle wider.

Some of my 14 tooth gears are 35 years old.....

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I guess a 19-stud wide solid steered axle is not that exciting, but I needed one and I don't think a lot (any?) have been posted in this thread. So here's one, with Ackerman steering geometry.

steered-solid-axle2.png

It is strong enough for the yellow springs, but probably it likes the softer ones better. Stud.io model and instructions for this that are interested.

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Posted (edited)

Hi,

After doing a lot of "research" i "designed" a front axle that i would like to share with you. The hubs and steering is copied from didumos's buggy.

The goal from the outset was to have the buggy's off road performance but with a faster speed.

I managed to integrate ackermann geometry and a castor angle (by tilting the whole assembly at 5 degrees)

640x480.jpg

I used the new differential with a 28 tooth driving gear so as to not get any excessive up and down gearing in the drivetrain.

 

800x450.jpg

The drive shaft splits to allow for the central placement of the servo.

 

640x360.jpg

Two L motors front and 4 L motors in the back.

 

It works pretty well, Although the steering rack catches on studs some times.

The final model is still in progress. 

 

Any remarks or advice is greatly appreciated!

 

The .io file is here https://bricksafe.com/pages/CharlesD/mark3-4x4

 

Edited by CharlesD

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On 9/21/2021 at 7:01 AM, Zerobricks said:

I discovered the old female CV connector 92906 can mate with the planetary hub's female CV joint!

Thank you!!! :thumbup: :classic:

this saved my excavator build!

due to tight space and all, I was trying to use a worm gear for final drive but that just made all the gearbox gears click. This setup is about 9:1 (or 1:9 whoever you write it) no clicking anywhere.

solid as a rock setup so I’ll use this for another track setup with single motor co-axle drive also.

I spaced them in 1 1/2 studs from the sprocket wheel as the tracks widen out. 
 

ada2dc6b-11c4-44bd-a51a-4160a0869923.jpe

59e8e718-a970-4e1b-b492-6fa83ce75078.jpe

0b171575-f6c4-4379-b26e-6f4852e9c828.jpe

 

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11 minutes ago, MangaNOID said:

Thank you!!! :thumbup: :classic:

this saved my excavator build!

due to tight space and all, I was trying to use a worm gear for final drive but that just made all the gearbox gears click. This setup is about 9:1 (or 1:9 whoever you write it) no clicking anywhere.


 

 



 

 

That's great ;)

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On 9/26/2021 at 5:08 PM, ludovisser said:

I guess a 19-stud wide solid steered axle is not that exciting, but I needed one and I don't think a lot (any?) have been posted in this thread. So here's one, with Ackerman steering geometry.

steered-solid-axle2.png

It is strong enough for the yellow springs, but probably it likes the softer ones better. Stud.io model and instructions for this that are interested.

Slight bending of the springs will occur when suspension is compressed.. 

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2 hours ago, MangaNOID said:

Thank you!!! :thumbup: :classic:

this saved my excavator build!

due to tight space and all, I was trying to use a worm gear for final drive but that just made all the gearbox gears click. This setup is about 9:1 (or 1:9 whoever you write it) no clicking anywhere.

solid as a rock setup so I’ll use this for another track setup with single motor co-axle drive also.

I spaced them in 1 1/2 studs from the sprocket wheel as the tracks widen out. 
 

 

I'm glad the idea helped you with your issue :sweet:

1 hour ago, Mechbuilds said:

Slight bending of the springs will occur when suspension is compressed.. 

Correct, the shock absorbers have no room to move sideways. I'd place them on the upper arm.

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8 hours ago, Mechbuilds said:

Slight bending of the springs will occur when suspension is compressed.. 

 

7 hours ago, Zerobricks said:

Correct, the shock absorbers have no room to move sideways. I'd place them on the upper arm.

In my MOC the travel is about 0.5 stud (a bit less even) and the space available between the shock absorbers and the black perpendicular connectors is enough to accommodate that without bending the springs. Compressing the full 1 stud indeed bends the shock ever so slightly, so if you need the full 1 stud travel you can consider putting the shock on the upper arms instead, as suggested. I don't have the space available for that though.

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