42131 Cat D11 Mods and improvements

[westphald]

Power Take Off (PTO) is an output shaft, usually found only on the rear of tractors, that allows the attachment of powered accessories, like a big drill.

I haven't read anything suggesting that the D11 has a PTO, so I'm pretty sure that is not what it is. It is probably suppose to represent the transmission.

[westphald]

On 8/30/2021 at 8:03 PM, Johnny1360 said:

That is cool start and I also had no idea that these beasts had any suspension at all, I always thought the best you could hope for was a spring under the seat, lol.

I'm surprised as well. I was wondering what @efferman was doing with the gray beams running between the track frames. Just learned it's called an equalizer bar and the track frames pivot back at the same point that the blade supports are attached. Certainly not suspension from a comfort standpoint, but does allow the tracks to adapt to the terrain better. I'm working on an improved (I hope) roller design, but I want the equalizer bar too.

Speaking of track frames and rollers, anyone else having trouble with the track shoes coming apart? Duplos (arguably too big, but we have a lot) cause it to happen often.

[jon hirst]

Struggling but tenacious . . . 2 studs narrower although the apparent width has been reduced by 4.  Two studs longer so the general scale has hopefully improved, 2 control boxes and room for lots of motors.
A long way to go but wondering if it would pay me to wait for someone clever to publish a full build !

Quick update . . getting complicated now, mainly due to my poor skills with drive chains and gearboxes
The 2nd control hub will have to go back in the engine compartment, but I've managed to get 3 motors side by side just above the chassis while the remaining one will fit just under the cab and work the upper rear ripper arms . . then a full rebuild of the cab and platforms, hopefully to an approximate scale !
Pics will follow in due course . . . 

  

Edited October 22, 2021 by jon hirst
update

[nugnug115]

On 10/21/2021 at 5:53 AM, jon hirst said:

Struggling but tenacious . . . 2 studs narrower although the apparent width has been reduced by 4.  Two studs longer so the general scale has hopefully improved, 2 control boxes and room for lots of motors.
A long way to go but wondering if it would pay me to wait for someone clever to publish a full build !

Quick update . . getting complicated now, mainly due to my poor skills with drive chains and gearboxes
The 2nd control hub will have to go back in the engine compartment, but I've managed to get 3 motors side by side just above the chassis while the remaining one will fit just under the cab and work the upper rear ripper arms . . then a full rebuild of the cab and platforms, hopefully to an approximate scale !
Pics will follow in due course . . . 

  

looking forward to seeing the progress pics , my progress has been super slow , im waiting on 1 more bricklink order to come in then ill be able to complete my newly designed track layout , then ill be able to work on the internals and get the ripper assembly started , cant wait to share my progress !

[jon hirst]

Finally got a simple working ripper . . .

Edited October 25, 2021 by jon hirst
no longer needed

[jon hirst]

I pressed on  . . 3 rebuilds and I've had enough, so although a few bits are unfinished . . . this is as far as I go.

And I have 9 black flip-flop beams, 5 short yellow panels and 4 x 1 stud little yellow panel/beams left over !

So on to the next project.  A big 8-wheeled mobile crane !

Edited October 26, 2021 by jon hirst
update

[westphald]

Anyone figure out a better solution for the idler slide? The rack is a nice setup, and it's easy to replace the worm gear with a shock absorber, but it's not very sturdy. Lateral movement in particular could be a concern if you want to drop the idler sprocket to the ground (not for most, but I plan on putting mine to work). Might even be a reason TLG lifted it.

Really, I have reason to open up the center some more. I could probably raise the rack up 1L, but then it's exposed to the world even more. I'm hopeful someone has some insight about sturdy slide mechanisms.

[nugnug115]

been super slow progress due to bricklink orders but i have finally completed the main structure for my track frames , the support holding the upper drive sprocket will be gone in the final design , so it will be very accurate to the real machine , i just have it there now so i can get a feel for the look of the track. Also the upper sprocket will be the one that has the drive motors connected to it , and each frame also has 8 rollers that are hard to see in the pics 

 

[nugnug115]

On 10/18/2021 at 12:25 AM, Ngoc Nguyen said:

Go nuts.

https://bricksafe.com/files/nguyengiangoc/42131.io

Hello , is there anyway you have this version with the tracks on it 

[Ngoc Nguyen]

20 minutes ago, nugnug115 said:

Hello , is there anyway you have this version with the tracks on it 

No I dont

[nugnug115]

have made lots of progress but theres still lots of work to be done lol. all functions are working except for the drop down ladder , ( 1 L motor for blade tilt , 1 L motor for blade elevation , 2 angle motors , 1 for each track , 1 L motor for bottom pair of linear actuators for the ripper , and 1 L motor for the top pair of linear actuators for the ripper, and 2 hubs , ) there will be one more L motor that will control the ladder 

 

Edited November 15, 2021 by nugnug115

[Dafgek81]

12 hours ago, nugnug115 said:

have made lots of progress but theres still lots of work to be done lol. all functions are working except for the drop down ladder , ( 1 L motor for blade tilt , 1 L motor for blade elevation , 2 angle motors , 1 for each track , 1 L motor for bottom pair of linear actuators for the ripper , and 1 L motor for the top pair of linear actuators for the ripper, and 2 hubs , ) there will be one more L motor that will control the ladder 

 

Does this version use a lot of extra parts besides the extra motors and hub??

[nugnug115]

3 hours ago, Dafgek81 said:

Does this version use a lot of extra parts besides the extra motors and hub??

unfortunately it does , theres around $150 in extra parts in the pics that you see in addition to some parts i had already , but if you have lots of yellow technic parts already you could save a lot of money 

[Ngoc Nguyen]

My PF Conversion mod for 42131 is available on rebrickable: 

https://rebrickable.com/mocs/MOC-92919/nguyengiangoc/42131-pf-conversion/

 

This mod allows the set 42131 to be controlled by PF elements. The PF elements in this mod are:

- 2 Battery Boxes
- 4 IR receivers
- 7 L motors

This version has 7 functions:

- Right track control
- Left track control
- Blade pitch
- Blade tilt
- Ripper pitch
- Ripper tilt
- Ladder control

Edited November 17, 2021 by Ngoc Nguyen

[nugnug115]

9 hours ago, Ngoc Nguyen said:

My PF Conversion mod for 42131 is available on rebrickable: 

https://rebrickable.com/mocs/MOC-92919/nguyengiangoc/42131-pf-conversion/

looks amazing , will you be building this model in real life ?

[Maaboo the Witch]

Two battery boxes? Heck, this thing would weigh a ton...

[Ngoc Nguyen]

7 hours ago, nugnug115 said:

looks amazing , will you be building this model in real life ?

I don't think I will. I have no plan to buy it because I'm out of space for Lego.

[Ngoc Nguyen]

Does anyone have a studio file for the new track?

[Ngoc Nguyen]

I wasn't quite happy with the first PF conversion mod I made, because of a few things:

- I wasn't sure if the motors will be able to drive the machine.  In the design, the two L motors are used for propulsion, and they are connected through one 12/20 meshing and the planetary hub which has a gear ration of 1/5.4, so the final ratio is 0.11 or 1/9. The motors have to move not only the model but also a V12 motor through a long drivetrain. Since I don't have the set to test it with me, I can't know if my design is adequate.

- The motor-receiver mapping is not optimal. The design uses 7 motors and 4 IR receivers and is controlled through the good old PF IR controller, so the optimal design to me should be: 2 motors for drive in 1 channel, 2 motors for blade in 1 channel, 2 motors for ripper in 1 channel, and 1 motor for ladder in the last channel. I wasn't able to achieve that. The main reason is that the motor for the ladder lies too close to a receiver that already controls one function of the ripper and can only be connected to it

So I went back and after several attempts I managed to solve those two problems:

- I put the L motors for drive further into the center and manage to get another gear-down meshing. So the drive from the motor to the sprocket now goes through 16/20 x 12/20 x 1/5.4, which is 0.08 or 1/11.25. Hopefully this should be enough.

- I simplified the drivetrain to the ladder and put one motor directly under the seat, so it can now connect to its own receiver in the back. The gearbox is also redesigned so that the two motors for the blade will now connect to a receiver on the right, and the two motors for the ripper will connect to a receiver on the left.

The model now uses 6 L motors and 1 M motor. The M motor is used to drive the ladder, and it was chosen instead of the 7th L motor is that the M motor is smaller and thus fits into the space under the seat.

The new instruction and new part list have been uploaded to the same Rebrickable link: https://rebrickable.com/mocs/MOC-92919/nguyengiangoc/42131-pf-conversion/

I also got a deal to buy a 42131 with no electronics for 300 EUR. I'm thinking about it.

Edited November 26, 2021 by Ngoc Nguyen

[2GodBDGlory]

4 hours ago, Ngoc Nguyen said:

I wasn't quite happy with the first PF conversion mod I made, because of a few things:

- I wasn't sure if the motors will be able to drive the machine.  In the design, the two L motors are used for propulsion, and they are connected through one 12/20 meshing and the planetary hub which has a gear ration of 1/5.4, so the final ratio is 0.11 or 1/9. The motors have to move not only the model but also a V12 motor through a long drivetrain. Since I don't have the set to test it with me, I can't know if my design is adequate.

When I built the set out of my collection, I did a very crude PF swap (not worthy of sharing), but I believe I used the exact same motor/gearing combination you originally had: the L reduced at 12:20 followed by planetary reduction. I was running it off of my 7.4V rechargeable camera battery, and it would move, but it struggled much more than it should have. I think you've made the right move adding more reduction!

[Ngoc Nguyen]

1 minute ago, 2GodBDGlory said:

the L reduced at 12:20 followed by planetary reduction. I was running it off of my 7.4V rechargeable camera battery, and it would move, but it struggled much more than it should have. I think you've made the right move adding more reduction!

Wow thanks for the information! Since now I put the motors further in the center I can add more reduction if needed.

[2GodBDGlory]

I just realized I forgot a detail with my setup: I was using the medium-sized sprockets rather than the large ones because I didn't have enough track links. Therefore, I would have had an extra source of reduction.

[Ngoc Nguyen]

Thanks to efferman I now have the part for the new link. I've put it into the Studio model and updated the link. You can get it here.

https://bricksafe.com/files/nguyengiangoc/42131.io

[Ngoc Nguyen]

My PF 42131 exhibits a strange phenomenon:

- On the mattress, one PF L motor can drive one track alone forward but not backward. When driving backward it keeps skipping the gear.
- On the hard floor, however, one PF L motor can drive one track alone both forward and backward.

Any idea why?

[Bartybum]

10 hours ago, Ngoc Nguyen said:

My PF 42131 exhibits a strange phenomenon:

- On the mattress, one PF L motor can drive one track alone forward but not backward. When driving backward it keeps skipping the gear.
- On the hard floor, however, one PF L motor can drive one track alone both forward and backward.

Any idea why?

I would assume it's just because of friction. It could be something to do with the tread profile or the track geometry that causes it.