Universal off-roader 4x4 V2

[dustblue]

6 minutes ago, Zerobricks said:

It calibrates according to the mechanical  limit angle, in my case it's 180 degrees and from that it knows it's 3 positions. It's basically deisgned to be sued with PU L motor and wave selectors.

Ah I see...mechanical limits!  no wonder why I never made it work...

[Lego Tom]

I too was looking forward to the video and it did not disappoint! Watching it blaze through the weeds brought the term "Bungle in the Jungle" to mind! Don't worry about small parts falling off, they fall off the 1:1 vehicles as well.

[Daniel-99]

Thanks for the video! It was very interesting to see the car in action. After I watched a video, I have a few more questions to ask.

1. SUSPENSION. As I understand, the suspension is made to be soft here, though It uses double (triple) hard 7L springs. Moreover, the springs are attached to the upper suspension arms, which is rather unusual for real cars. So I wonder, how much of a load upper suspension arms have to deal with. I would try to use hard 9.5 L sprigs attached to the lower suspension arms (with additional reinforcements) in order to reduce the load by 2-3 times.

2. TRAMSMISSION. Throughout the whole post and the video I was looking for and Information about Lubrication, and did not found one. Though I guess, the whole car wont work without Lubricated transmission due to plastic-melting RPM. I would add an info about Lubrication to warn all the people, who would build your car. 

3. 3-D GEAR. Planetary hubs serve great for the trial purposes, but they are not as good for fast cars (18 km/h is a high speed for Lego). Firstly, planetary hubs have quite a lot of inner friction, so they really reduce the efficiency of the transmission on high-speed. In addition, with planetary hubs one has to spin the whole transmission 5.4 times faster to achieve the same speed. Even fast outputs of BM could not provide such RPM, so additional gears are required (Again, this reduce the efficiency). As you said, the car loses control at 18 km/h speed, and this could not be fixed without positive caster angle and changes in suspension (in particular, one should remove the tilting mechanism at the front with a anti-roll bar). Summing up, I would use a 2-speed gear box, with a fewer components (expensive by now), and lower "high speed". This will not the limit the off-road capabilities at all! 

I would say, that your car is the most practical, playble and multi-task off-roader made with Lego bricks, Buwizz units and additional Lubrication. Though the 3-speed gearbox (with rare parts) is excessive here.

[dustblue]

51 minutes ago, Daniel-99 said:

 3. 3-D GEAR. Planetary hubs serve great for the trial purposes, but they are not as good for fast cars (18 km/h is a high speed for Lego). Firstly, planetary hubs have quite a lot of inner friction, so they really reduce the efficiency of the transmission on high-speed. In addition, with planetary hubs one has to spin the whole transmission 5.4 times faster to achieve the same speed. Even fast outputs of BM could not provide such RPM, so additional gears are required (Again, this reduce the efficiency).

I'd like to try answer this one for zero from my own experience & experiment (because I did learnt a lot from zero's past videos). 

In lego technic world, torque is a much more difficult bitch to deal with(relative to rpm) without a wheel side gearing down, because of the plastic axles. I have tested many times, the highest torque a plastic axle can tolerate, is 3 buggy motor torque(I would use BT instead here after), any higher than 3BT, the alxe would be permanantly destroyd. Since power=Torque*RPM, you have to make sure the torque is within operating limits of your plastic parts. And the easiest way to do that, is using 46490(the planetary wheel hub). And in fact 46490 is very efficient comparing to for example design your own lego planetary reduction(I did that, workable but not as good as 46490, I used it for other reasons).

You can also use carbon fiber axle(max 6BT) or metal alloy axles(max 15BT), I use those a lot, but even for metal alloy axle, 15BT is not very high at all(without using 46490), you can easily surpass that if you use say 4 buggy motors and a central gear box. So 46490 is really a must for powerful mocs.

 

And even if you only use metal alxe, there is still some function you must use plastic parts, like a vc joints in live axle design( the axle can move in and out freely of that part), that part can tolerate only 3BT too. 

 

For  zero's moc this one, I believe he is using 46490 for other reasons too, like to use more fragile 12 bevel gears in the transmission, I personally hate this gear, I only use them in the differentials.

 

And I agree with you, Zero is speeding up the rpm just to use 46490 later, so without heavy lubrication it would be a disaster.

 

[deehtha]

12 hours ago, Daniel-99 said:

1. SUSPENSION. As I understand, the suspension is made to be soft here, though It uses double (triple) hard 7L springs. Moreover, the springs are attached to the upper suspension arms, which is rather unusual for real cars. So I wonder, how much of a load upper suspension arms have to deal with. I would try to use hard 9.5 L sprigs attached to the lower suspension arms (with additional reinforcements) in order to reduce the load by 2-3 times.

The reason to put the shocks on the upper arm is so that all the forces are pushing the wheel hub into the arm so that the hub does not pop out during suspension travel.

[gyenesvi]

Great model, and thanks for the great experiment; that's all I needed to know about the new gearbox parts :) So they are useful in practise, even for high torque applications; really good news!

The independent left-right drive with such a high travel independent suspension is also something I want to try with a similar Buwizz motor/gearbox layout (just with 2 speeds). The third speed is just the icing on the cake!

[Krxlion]

Sheeeesh! What a model, I already commented your video, but I will also speak few words here. First of all, you made me dust out my two Buwizz 3.0 units, just to take a look at that gearbox module in the app! The idea of having two separate driveshafts is a definition of thinking outside of the box, great! Front suspension is something that I was aiming a while back and trying to do in my own MOC, but we will see in the future. I see that the rear one is acting a little bit pendular as well, which is quite nice. I guess due to pendular type of suspension and long steering arms it could act a little too "wobbly" on high speed, but I do not count it as big disadvantage (after all this is an off-road vehicle). I think that 3-speed gearbox is something phenomenal in such small model and we can see for sure an upgrade from previous version, but I believe that two-speed are ideal for multipurpose car. @gyenesvi created a simple and robust gearbox in his C-model of Zetros with 3:1 and 1:1 gear ratio. With new bricks, we could squish that gearbox into 4 stud area, which just blows my mind. Anyway, I think that this model is the best one in being versatile of all the models (that uses Technic and Buwizz) I know. Great job and looking forward to your next projects!.

[gyenesvi]

8 hours ago, Krxlion said:

@gyenesvi created a simple and robust gearbox in his C-model of Zetros with 3:1 and 1:1 gear ratio. With new bricks, we could squish that gearbox into 4 stud area, which just blows my mind.

Just for the record, I was not the first to use the old differential piece to achieve the 3:1 gear ratio in a gearbox, I believe @Zerobricks have also used it before. But yeah, I guess we are all excited that such constructions can now be shrunk drown from 8 to 4 studs in length, that's a significant improvement :)

[blondasek]

Amazing model, but only as a curiosity. Cost of buwizz partz alone, with current sale, is ~420 euro witout tax (so around 500 euro with ~20% VAT) - this disqualify this from making it to have fun...
It is always nice to see :)

PS. I think I will stay with my modified Buggy which may only goes ~9-10km/h but at least was much cheaper :D

[Zerobricks]

On 10/30/2023 at 2:48 PM, Daniel-99 said:

Thanks for the video! It was very interesting to see the car in action. After I watched a video, I have a few more questions to ask.

1. SUSPENSION. As I understand, the suspension is made to be soft here, though It uses double (triple) hard 7L springs. Moreover, the springs are attached to the upper suspension arms, which is rather unusual for real cars. So I wonder, how much of a load upper suspension arms have to deal with. I would try to use hard 9.5 L sprigs attached to the lower suspension arms (with additional reinforcements) in order to reduce the load by 2-3 times.

2. TRAMSMISSION. Throughout the whole post and the video I was looking for and Information about Lubrication, and did not found one. Though I guess, the whole car wont work without Lubricated transmission due to plastic-melting RPM. I would add an info about Lubrication to warn all the people, who would build your car. 

3. 3-D GEAR. Planetary hubs serve great for the trial purposes, but they are not as good for fast cars (18 km/h is a high speed for Lego). Firstly, planetary hubs have quite a lot of inner friction, so they really reduce the efficiency of the transmission on high-speed. In addition, with planetary hubs one has to spin the whole transmission 5.4 times faster to achieve the same speed. Even fast outputs of BM could not provide such RPM, so additional gears are required (Again, this reduce the efficiency). As you said, the car loses control at 18 km/h speed, and this could not be fixed without positive caster angle and changes in suspension (in particular, one should remove the tilting mechanism at the front with a anti-roll bar). Summing up, I would use a 2-speed gear box, with a fewer components (expensive by now), and lower "high speed". This will not the limit the off-road capabilities at all! 

I would say, that your car is the most practical, playble and multi-task off-roader made with Lego bricks, Buwizz units and additional Lubrication. Though the 3-speed gearbox (with rare parts) is excessive here.

1. The front uses triple shock absorbers, since they don't get comprssed all the way due to suspension limiters in order to prevent the steering links from popping out. I am not using 9L shock absorbers, since there's no way to mount them on lower arm due to the steering link being in the way and because they are no longer produced.

2. I agree, forgot to mention it, I use Molykote PG75.

3. Ideally I would use geraboxes only to gear down to the hubs, but due to the nature of LEGO tranmissions (especially when it comes to high torque) the only way is to gear high and have the final gearing as close or on the wheels. Of course I can easily remove the third gear and save some 100 parts, but a new version can't end up slower than the previous one, you know

I think with a very light enough model, you could maybe get away with direct drive to the Audi's hubs via new diffs and actual gearing down in the gearbox, but I would be worried about other factors such as windup which would cause wheels to oscilate... Might be worth a try though, since geraing down once is far more efficient than gearing up and down again.

 

Edited November 6, 2023 by Zerobricks

[Daniel-99]

Thank you for a detailed answer!

15 hours ago, Zerobricks said:

I am not using 9L shock absorbers, since there's no way to mount them on lower arm due to the steering link being in the way and because they are no longer produced.

Got you! It is very unfortunate for me, that 9L shock are no longer in stock, cause they have the best sprigs among all.

15 hours ago, Zerobricks said:

2. I agree, forgot to mention it, I use Molykote PG75.

That is good to know, cause not all greases fit well to Lego parts, as far as I know.

15 hours ago, Zerobricks said:

3. Ideally I would use geraboxes only to gear down to the hubs, but due to the nature of LEGO tranmissions (especially when it comes to high torque) the only way is to gear high and have the final gearing as close or on the wheels.

Agreed! 

15 hours ago, Zerobricks said:

Of course I can easily remove the third gear and save some 100 parts, but a new version can't end up slower than the previous one, you know

I believe many people would appreciate a V2 model with 2-speed gearbox, cause it will be easier to build, but I understand the technical interest in the 3-speed solution as well! 

15 hours ago, Zerobricks said:

I think with a very light enough model, you could maybe get away with direct drive to the Audi's hubs via new diffs and actual gearing down in the gearbox, but I would be worried about other factors such as windup which would cause wheels to oscilate... Might be worth a try though, since geraing down once is far more efficient than gearing up and down again.

That would be very interesting to see! Such an experiment would show us the limitations of the Audi`s hubs. I am looking forward to test them by myself, though I do not want to buy a whole bunch of black parts and C+ electric components.

[Infinity Bricks]

@Zerobricks I can't get your design in ldd or bricklink. Most of the parts are glitched out and there are quite a few floating pins. Can you send the instructions or at least the version that you used. 

[Zerobricks]

7 hours ago, Infinity Bricks said:

@Zerobricks I can't get your design in ldd or bricklink. Most of the parts are glitched out and there are quite a few floating pins. Can you send the instructions or at least the version that you used. 

Please see here:

 

Edited June 28, 2024 by Zerobricks

[Zerobricks]

Decided to take apart the model after the gathering, since it was full of dirt which was starting to jam the gearbox amongst others. Two washing machine cycles later, the bricks were ready to be rebuilt back and this time I took some photos of the (re)build:

The build starts with the bottom of the model which provides structural support and ingress protection:

Afterwards the lubricated driveline parts are added. So many pretty colors:

Two PU L motors are placed on top of the driveline. The one on the left is used for steering, while the one on the right controls the gearbox:

A quick gerabox test:

With the main base more or less complete, it's time to build the front axle. Here is how it looks from the front side:

And another photo of the front axle, this time from the rear side:

The front axle is attached and interlocked to the main chassis using a few 5 studded axles with stops and a structure holding the steering rack in place is added in front:

Rear axle is sandwiched between two 5x7 frames which with the help of lever keep it together. It's designed as a standalone module and attached using orange pins:

The red lights on the rear of the rear axle cover the drive axles and preventing the dirt from getting in there. Also notice the towing hitch which has yet to be used:

Now that the rear axle has been firmly attached, we have a rolling chassis:

A bit of cable managment and a bodywork later and the model is finished:

I hope you find these photos interesting and please let me know if you have any questions!

Edited August 19, 2024 by Zerobricks

[1gor]

I have noticed that you also combine 8 tooth gear with 28 tooth on red diffefential. My question is: how smooth does this combination work? Is it strong enough soulution (since it is not in line, but more some L shaped combination) when using coupled large motors for drive to have some 106Ncm torque after another red differential with 12 tooth gear on axles?

Kind regards. 

Edited August 19, 2024 by 1gor

[Zerobricks]

3 minutes ago, 1gor said:

I have noticed that you also combine 8 tooth gear with 28 tooth on red diffefential. My question is: how smooth does this combination work? Is it strong enough soulution (since it is not in line, but more some L shaped combination) when using coupled large motors for drive?

Kind regards. 

It's a totally legal and smooth mesh, the number of gears are same as 16 and 20 for example 36. It has yet to slip so far, the fact it's being geared up helps a lot.

[1gor]

I know that it is legal; just looking what to do on my project to save number of gears to make efficient drivetrain as possible because I have very very limited space...

...and I use it for downgearing (8 tooth is on large motor)...

Thanks.

Edited August 19, 2024 by 1gor

[1gor]

20 hours ago, Zerobricks said:

It's a totally legal and smooth mesh, the number of gears are same as 16 and 20 for example 36. It has yet to slip so far, the fact it's being geared up helps a lot.

Today I made chassis with live axles powered with coupled Large motors. I use 8 to 28 (red differential because I use at front 94.3 and 107 rear tires) directly from motors and 12 to red 28 tooth differential at axles...it seems that I have several generations 12 tooth double bevel gears because I found combination that runs very very smooth like daytona differentials. Did you have similar ecperience? I can't recall frpm what year are which because they are all black color... 

[Zerobricks]

4 hours ago, 1gor said:

Today I made chassis with live axles powered with coupled Large motors. I use 8 to 28 (red differential because I use at front 94.3 and 107 rear tires) directly from motors and 12 to red 28 tooth differential at axles...it seems that I have several generations 12 tooth double bevel gears because I found combination that runs very very smooth like daytona differentials. Did you have similar ecperience? I can't recall frpm what year are which because they are all black color... 

I can't say, have no black versions... But the material did change, old ones would break when overloaded, while the modern ones slip and deform.

[1gor]

10 minutes ago, Zerobricks said:

I can't say, have no black versions... But the material did change, old ones would break when overloaded, while the modern ones slip and deform.

Well, total torque on axle is about 106Ncm, so I think I'm far away from that situation...anyway I'm happy with simple amd very sturdy chassis