[MOC][WIP] John Deere 8R Tractor

[Jundis]

Hey guys and gals,

whenever I don't know what to build next or stuck with a current MOC (looking at you, pesky crane); I build a Tractor.

This time I tried to improve on my Fortschritt ZT 320 and wanted to add AWD and a front hitch. As Deere Tractors have a longer nose, it was my choice. And as a new 8R came around, this will be the loose aim, especially the 8R 410:

  

Currently I am waiting for a new Li-Ion battery for the buwizz as the last battery died on the shelf, forgot to load it for half a year... :-/

The functions, powered by a Buwizz 3 are:

- Drive (PU-L-Motor)
- Steering (PU L-Motor)
- rear PTO (PF L-Motor)
- rear hitch (PF L-Motor)
- front hitch (PU L-Motor)

The front axle gave me the most headache. Made it even harder as the aim was to give it a 0.5 stud offset to the chassis, as I wanted it to be more leveled with the selected tire combination. I settled with a solution that unfortunately has an illegal building technique, the front pnedular point is 2 studs below the rear one... but this is way sturdier than all the other solutions to build around and as the pendular motion is limited in travel, I don't feel that there is too much stress on the frame.

For the rear drive, the reversed portal axles give a little more space above for the PTO and rear hitch

Here is a view of the mechanics and real pics.

Not quite happy about the front hitch... hopefully can cover it to get the nose shape etched out a bit more. Pneumatic solution with a autovalve would be even bulkier, though.

As there are no curved panels in green color, I will go with a brick-built solution on the hood. But first, the function test with Buwizz next week :-)

[jorgeopesi]

Very good and compacted I like a lot specially the front axle solutions.

[1gor]

It seems that you use this kind of axle.

 

 

How do you compensate speed rotation difference between front and rear tires

[2GodBDGlory]

Looks nice! I like the assymmetry in the front axle, and the use of that triangle part for the steering linkage is clever!

[1gor]

51 minutes ago, 1gor said:

It seems that you use this kind of axle.

 

 

How do you compensate speed rotation difference between front and rear tires?

I forgot one more thing; how much you can bend PU cables (they stick out very much) in order to work properly; I had a lot of cable issues with PF motors, so I have to fix 5 PF servos, two large motors (4 XL are fixed, but plastic looks like T-rex took it apart).

First stage of Alzheimer...

[Jundis]

Thanks, guys!

3 hours ago, 1gor said:

It seems that you use this kind of axle.

How do you compensate speed rotation difference between front and rear tires

Yeah, it actually gives more space on the sides so the tires don't scratch the frame even when fully turned and maximum pendular movement.

I just did a quick calculation before. Here it comes in handy, that the 1/2 stud offset of the front axle allows the 12/28 gear combination.

The remaining difference is neglectable by friction itself. It's not that fast, but torque is more important for me, as it only has 1 L-motor for drive.

3 hours ago, 1gor said:

I forgot one more thing; how much you can bend PU cables (they stick out very much) in order to work properly; I had a lot of cable issues with PF motors, so I have to fix 5 PF servos, two large motors (4 XL are fixed, but plastic looks like T-rex took it apart).

Puh, good question. I didn't care much about cable management so far in this built. Just left enough space for it to go to the Buwizz.

[1gor]

15 minutes ago, Jundis said:

Thanks, guys!

Yeah, it actually gives more space on the sides so the tires don't scratch the frame even when fully turned and maximum pendular movement.

I just did a quick calculation before. Here it comes in handy, that the 1/2 stud offset of the front axle allows the 12/28 gear combination.

The remaining difference is neglectable by friction itself. It's not that fast, but torque is more important for me, as it only has 1 L-motor for drive.

Puh, good question. I didn't care much about cable management so far in this built. Just left enough space for it to go to the Buwizz.

Yesterday I got BuWizz 3.0, so I plan do finally work on Fastrac next week (my head will explode since last days when I went to work were up to 120km/h wond blowing speeds)...

Usually when you use such tire combination, easiest way is to use central differential and (no matter 12-28, 14-22 or 20-28 combo at axles) 12 to 20 refuction at portals on rear...hope I could make it sompler for you...

[falconluan]

Very promising progress you made here Especially packed lots of motors/functions in such tight space.

Lots of 8R have independent suspenstion which I failed to achieve in my version, I was hoping the new suspenstion parts can help, seems still very challenging, unless get rid of the horizontal placed diff, which will take extra space in the chassis and lost extra realism...