[MOC]Falconluan's technic tractor MOC series: RC Case Magnum Rowtrac

[1gor]

You can make all in the same line, but make front suspended axle like on Unimog U400 using ball joint...

[falconluan]

27 minutes ago, 1gor said:

You can make all in the same line, but make front suspended axle like on Unimog U400 using ball joint...

That's a good idea    Interesting that I planned to make a suspended axle in next MOC as part of iteration process .

Another solution I can think of is accepting the 1 stud height difference. Use 20 to 16 gear pair followed by 16 to 16 gear pair to achieve 1 stud height diff. By doing so will create a 5mm higher sitting rear axle than front and it may look better than a higher front anyway.

Edited January 2, 2024 by falconluan

[1gor]

That is also a possibility

[falconluan]

Some update 

The height diff between front and rear axle is now reduced to 1 stud as @1gor and @Jundis suggested.  Other change includes steering link moved to the backend of axle, making some room for the fake engine. Lot of places still need to be further reinforced.

[Cypr-21]

On 1/2/2024 at 7:41 AM, 1gor said:

To use 4wd with 81 mm at front and 107mm rear, you have to use 12 to 28 tooth at front differential (as you made) but use 20 to 28 tooth at rear because rear tire has bigger rolling circumference (front 81mm × 3.14, rear 107 x 3.14)

I think it's not necessary to have different ratios if using a central differential, isn't it ?

It's the differential purpose to make the speed difference between front and rear axles.

[1gor]

2 hours ago, Cypr-21 said:

I think it's not necessary to have different ratios if using a central differential, isn't it ?

It's the differential purpose to make the speed difference between front and rear axles.

Up to some extent central diffrrential can compensate front wherl overspin, but you have to calculate correlations between front and rear tires and use approximate upgearing or downgearing,

Example when combining 81mm and 107mm you have to use 12 to 28 tooth differential at the rear and 20 to 28 tooth differential gear at the front. When compared rear to front tires you get 107/81 ~~ 1.321 relation and closest way to maintain similar speeds on differentials is 20/12 ~~ 1.66. Diffefence between 1.321 and 1.66 can compensate with central differential...

[zoo]

You also want the option to lock the center differential. Then you need to match front and rear tire traction. I believe it's not necessary to be 100% match but still very close.

[2GodBDGlory]

Would it be correct that if you fail to have the two axles geared similarly, you'll have some kind of "torque vectoring" going on, with more torque going to the front axle, and less going to the rear, even though the rim speed of each wheel would be the same?

I believe that kind of thing is done in AWD cars in real life, though I doubt it's like that for tractors.

[1gor]

12 hours ago, 2GodBDGlory said:

Would it be correct that if you fail to have the two axles geared similarly, you'll have some kind of "torque vectoring" going on, with more torque going to the front axle, and less going to the rear, even though the rim speed of each wheel would be the same?

I believe that kind of thing is done in AWD cars in real life, though I doubt it's like that for tractors.

Real cars have practically same diameter wheels at the front and back, and mostly tractors have some 25% smaller tires at the front, so locking central differential is not used on tractors; they have more hydrostatic torque splitter for front axle (usually rear is directly powered), so locking differential is not the brigthest idea here; real tractors have something like this part (but haven't tested it yet)

 

[2GodBDGlory]

4 hours ago, 1gor said:

Real cars have practically same diameter wheels at the front and back, and mostly tractors have some 25% smaller tires at the front, so locking central differential is not used on tractors; they have more hydrostatic torque splitter for front axle (usually rear is directly powered), so locking differential is not the brigthest idea here; real tractors have something like this part (but haven't tested it yet)

Interesting!
While cars do have essentially the same size wheel all around, my understanding is that they could have different gear ratios front/rear for torque vectoring, which would have the same effect. Though it's probably more likely that they use some kind of fluid coupling like you mentioned tractors use!

Anyways, that's probably enough off-topic for me...

[1gor]

3 minutes ago, 2GodBDGlory said:

 

Anyways, that's probably enough off-topic for me...

...and very very difficult to achieve with LEGO...

Kind regards

[zoo]

4 hours ago, 1gor said:

Real cars have practically same diameter wheels at the front and back, and mostly tractors have some 25% smaller tires at the front, so locking central differential is not used on tractors; they have more hydrostatic torque splitter for front axle (usually rear is directly powered)

I see. Last tractor I drove was a Case IH 5140 a long time ago. I got this picture in my head that you could see the front wheels turning a tiny bit too fast when the four wheel drive was fully engaged. Couldn't find much info on the drivetrain online.

[1gor]

1 hour ago, zoo said:

I see. Last tractor I drove was a Case IH 5140 a long time ago. I got this picture in my head that you could see the front wheels turning a tiny bit too fast when the four wheel drive was fully engaged. Couldn't find much info on the drivetrain online.

I have this info from local AGCO dealer (I have visited them because I had some questions about Fastracs...). They also have Fendt (rear differential and transmission box as they call it pictured below), Massey Ferguson, Steyr...

Shaft pictured in lower left corner goes directly to front differential and dark gray cylinder shaped part in the lower central part of picture acts similar to central differential, but it is not mechanically splitting torque and power, but hydrodrostically, something like white 24 tooth gear with clutch that "slips" when to high rezistance is present...only that real system distributes torque to wheel(s) that have higher redistense (traction). On street (distrybutors say that) trac uses mostly rear wheen drive.

I hope that I did't derail your topic too much.

Edited January 6, 2024 by 1gor

[falconluan]

15 hours ago, 1gor said:

I hope that I did't derail your topic too much.

If you meant that you derailed my moc introduction topic then you did not at all. The discussion above is very informative and I enjoyed reading them very much. I've read and watched the drivetrain pics and videos like you pasted as well and found it very hard to replicate with lego, at least for me to do so ...

So I set my minimum goal of my first bigger tractor moc as a directly enlarged moc of my smaller one, I take any function beyond that as a bonus. Then I will try to improve the chassis with following iterations and mocs gradually.  

[1gor]

That is similar approach that I had, only when I started, there were no frames etc to give me desired stiffness. First time I had idea to make John Deere 8 series trac with independent suspension which was utophia at that time (before narrow differential and before narrow universal joints...).

I'm glad if I can help, so you want repeat my mistakes (broken parts etc...)

[falconluan]

8 minutes ago, 1gor said:

I'm glad if I can help, so you want repeat my mistakes (broken parts etc...)

Thank you for offering help and you've already helped me 

As to broken parts, I will definitely ask you for more help when I want to power my tractors 

[1gor]

2 hours ago, falconluan said:

Thank you for offering help and you've already helped me 

As to broken parts, I will definitely ask you for more help when I want to power my tractors 

Currently working on similar problem...

[Cypr-21]

On 1/5/2024 at 5:19 PM, 1gor said:

Up to some extent central diffrrential can compensate front wherl overspin, but you have to calculate correlations between front and rear tires and use approximate upgearing or downgearing,

Example when combining 81mm and 107mm you have to use 12 to 28 tooth differential at the rear and 20 to 28 tooth differential gear at the front. When compared rear to front tires you get 107/81 ~~ 1.321 relation and closest way to maintain similar speeds on differentials is 20/12 ~~ 1.66. Diffefence between 1.321 and 1.66 can compensate with central differential...

Thanks for the complete answer !

[falconluan]

The chassis is somewhat finished, there is very limited space since a realistic scaled chassis width is 5L. Also since it is now a 4 cylinder engine, I think I'm now building a 6400 series

[Jandel47]

16 hours ago, falconluan said:

The chassis is somewhat finished, there is very limited space since a realistic scaled chassis width is 5L. Also since it is now a 4 cylinder engine, I think I'm now building a 6400 series

Im a farmer IRL and in the past 15 years we had 5 different models of the 6400 series and today we still own one of them. I have spent thousands of hours in these tractors and it really makes me happy to finally see someone creating this, IMO, best tractor ever made in Lego. 

If you need more information about the real life model, like specific photos or info from the owners manual, feel free to ask me. 

 

Are you planning on making a tier 2 or 3?

Keep up the good work!

 

Greetings, Jan

[1gor]

@falconluan instead perpendicilar connector and connector #1 on front axle to hold steering hub, it would be sturdier to use those:

https://www.bricklink.com/v2/catalog/catalogitem.page?P=60484#T=S&C=85&O={"color":85,"iconly":0}

and

https://www.bricklink.com/v2/catalog/catalogitem.page?P=33299#T=C

Edited January 15, 2024 by 1gor

[falconluan]

8 hours ago, Jandel47 said:

If you need more information about the real life model, like specific photos or info from the owners manual, feel free to ask me. 

Hi @Jandel47, thank you for your offer for help , also if you don't mind, please feel free to point out the places of it you think needs to be improved. 

9 hours ago, Jandel47 said:

you planning on making a tier 2 or 3?

That's a very detailed info which I didn't know before. I knew that that are two different looks of the hood of the 6400/7400 tractors, and I'm planning to build the newer version. A quick google search told me that there are other difference between them like engine, suspension, etc. Basically, my target is the die-cast model like below:

 

Currently, I'm working on the rear fenders, and I made two versions, a wide one and a narrow one, the 

I checked the "Farmer Phil" YT channel where he has a wide tyre 6499, the red potion of rear fender does cover almost all the width of tyre. So I think the wider version is better, although it has a down side of more red 3# connectors are needed.

What do you think?

Thanks @1gor for your suggestion.

Here is a closer look of the hub support structure. Due to the space for pivoting, the space above the 1L beam(between 6536 and 41677) needs to be not occupied. So if a T shape beam put there, only its end tip pin hole is available to be used which is not very stable as well. 

[Jandel47]

 

17 hours ago, falconluan said:

That's a very detailed info which I didn't know before. I knew that that are two different looks of the hood of the 6400/7400 tractors, and I'm planning to build the newer version. A quick google search told me that there are other difference between them like engine, suspension, etc. Basically, my target is the die-cast model like below

The diecast model is probably a 6480 or 7480? Either way that is a 6 cylinder tractor. The 6400 serie has been produced in roughly three scales; small 4 cyl frame, medium 6 cyl frame and large 6 cyl frame.

It depends on how realistic you want it to be, but ideally you need to sqeeze in a 6 cyl engine.

I dont have the measurments of your build but looking at your build, the overall size and wheelbase and size of the cab compared with the rest, I think a 6465/80 or 7465/80 comes closest to your build, so the mdeium 6 cyl frame. In this case the wheelbase may be a little too long but the overall shape is very recognisable!

 

17 hours ago, falconluan said:

I checked the "Farmer Phil" YT channel where he has a wide tyre 6499, the red potion of rear fender does cover almost all the width of tyre. So I think the wider version is better, although it has a down side of more red 3# connectors are needed.

What do you think?

The wide fenders are spot on! They look really good.

Im not sure how wide the 45mm wide lego tractor tires would be IRL, but I know that IRL it will take 710 mm wide tires in order to stick out a few centimeters from under the fenders. Our 6480 had 650 mm wide tires and being on the widest track with, both wheel and fender were evenly wide. I believe the 6499 from Farmer Phil has 710s. But, as mentioned before, the 6499 is a large frame and your diecast probably a medium frame. Although visual differences on photos etc. might seem little, a 6499 is considerably bigger than a 6480, while the cab remains the same size. 

Obviously it is up to you, but I would go for a 64/7480.

[falconluan]

Wow, that is a very informative comment, thank you @Jandel47

5 hours ago, Jandel47 said:

 

The diecast model is probably a 6480 or 7480? Either way that is a 6 cylinder tractor. The 6400 serie has been produced in roughly three scales; small 4 cyl frame, medium 6 cyl frame and large 6 cyl frame.

It depends on how realistic you want it to be, but ideally you need to sqeeze in a 6 cyl engine.

I dont have the measurments of your build but looking at your build, the overall size and wheelbase and size of the cab compared with the rest, I think a 6465/80 or 7465/80 comes closest to your build, so the mdeium 6 cyl frame. 

You are correct, the diecast model is a 7480. And because of that I was planning to build a 6480/7480 at the beginning, yet to find the 6-cy engine is quite a challenge. Even I get rid of the small turnable to allow the steering rack moved further back, there is no easy way to have a 6 pin thin beam setup easily for the engine. If use a normal beam instead, it means more height(5L) and the available height under the front part of hood is 4L...

 

5 hours ago, Jandel47 said:

In this case the wheelbase may be a little too long but the overall shape is very recognisable!

Based on my very inaccurate measure, the ideal wheelbase is between 19 and 20L, current setup is 20L, I can shorten it after the central structure is finished and it stills looks too long.

 

5 hours ago, Jandel47 said:

The wide fenders are spot on! They look really good.

Im not sure how wide the 45mm wide lego tractor tires would be IRL, but I know that IRL it will take 710 mm wide tires in order to stick out a few centimeters from under the fenders. Our 6480 had 650 mm wide tires and being on the widest track with, both wheel and fender were evenly wide. I believe the 6499 from Farmer Phil has 710s. But, as mentioned before, the 6499 is a large frame and your diecast probably a medium frame. Although visual differences on photos etc. might seem little, a 6499 is considerably bigger than a 6480, while the cab remains the same size. 

Obviously it is up to you, but I would go for a 64/7480.

Then I'll keep the wide fender and consider it a 64/7480 with wide tires 

[falconluan]

Some update:

I ditched the small turnable in the front axle using the big ball joint instead. By doing this,  I can have more length for the fake engine, it also can prepare adding suspension to the front axle.

Squeezed in a 4wd/rwd switch. Still figuring out the place for the control lever though.

Rebuilt the rear hitch by making it more sturdy and compact. The front hitch needs to be rebuilt as well.

 

The cabin and rear fender are almost finished. Will probably make a hole in the roof for HoG steering.