anyUser

42112 Concrete Truck improvement/modification (WIP)

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I thought I might start one:

In the Set topic thread there was some discussion if the drum would unload if pushed backwards. At about the same time a small setup at Rebrickable reminded me of an improvement.

I believe that I got a working setup now:

20200621_164337.png

20200621_165643.png

 

 

 

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Posted (edited)

Can the cement bucket tilt in order to dump the contents in the official model? not sure how realistic that is compared to a real cement truck.

Edited by SNIPE

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Posted (edited)
1 hour ago, SNIPE said:

Can the cement bucket tilt in order to dump the contents in the official model? not sure how realistic that is compared to a real cement truck.

Not sure if you are asking how a concrete truck works, but in any case I thought the image below is nice to see.

No concrete truck I know tilts the drum to unload, I think a loaded drum is too heavy to tilt and dumping concrete like that would result in an uncontrolled mess. The drum has two Archimedes screws inside, if the drum spins clockwise, the content is pushed towards the truck cabin, but since that end of the drum is closed, the concrete is continuously being mixed. When the drum spins counterclockwise, the liquid concrete is carried toward the rear of the truck, where the drum has an opening, and is being fed in the chute towards the area where is it is needed. The drum is never completely full: imagine a horizontal line around the top of the truck cabin, that is the maximum concrete level. The screw combined with the variable rotating speed makes precise dosing possible.

structure.png

 

Edited by Cumulonimbus

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2 hours ago, SNIPE said:

Can the cement bucket tilt in order to dump the contents in the official model? not sure how realistic that is compared to a real cement truck.

I haven't seen any hint in the relased set pictures that indicate that the drum can be raised.


However, it might be possible that the cabin can be tilted forward to access the four(?) cylinder engine. The diagonal (light grey) beam could indicate this.

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1 hour ago, anyUser said:

I haven't seen any hint in the relased set pictures that indicate that the drum can be raised.


However, it might be possible that the cabin can be tilted forward to access the four(?) cylinder engine. The diagonal (light grey) beam could indicate this.

Mmm no, I don't think the cab will tilt. If so, they had surely shown it on the rear of the box. And I also think the engine is visible between the 2 seats exactly for this reason (no tilting cab).

What is not accurate in this cement mixer is the rear "half pipe" to download cement. It looks like sliding instead of folding in the middle (never seen it in real life).

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Posted (edited)
On 6/22/2020 at 11:43 AM, mpj said:

Mmm no, I don't think the cab will tilt. If so, they had surely shown it on the rear of the box. And I also think the engine is visible between the 2 seats exactly for this reason (no tilting cab).

What is not accurate in this cement mixer is the rear "half pipe" to download cement. It looks like sliding instead of folding in the middle (never seen it in real life).

I haven't seen a box picture yet.

I didn't download the box pictures as there appeared no more relevant information. The setup of the HOG control for steering prohibits tilting of the cabin.

This is my quick guess for the pipe:20200622_125446.png

Note that is is attached to the chassis quite low. Therefore folding is not reasonable here.
In the picture above it is obvious, that the chute is fixed at its upper end with a support at the lower. Soem of these are modular so that you can use different attachments:

dcp_9750a.png
(Conneting to a 150 mm tube to increase reach. The original chuts is on the right mudguard.)

Edited by anyUser
Remark on box picture changed

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Posted (edited)

Made some progress:

1. Gearbox for drum set up with unidirectional turning when driven from rear axle. There is a ca. 50 cm (distance) lag between forward/backward change and start of rotation. Speed should be OK.

2. Steering axle setup. I believe that I got better steering angle and thus smaller turning cycle.

3. Cabin can be tilted forward, doors can be opened, and mirrors added.

421_20200629_161204.png

415_img_3383.png

Edited by anyUser
200628: pictures updated, 200629: picture update

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The (original) model is missing the funnel to fill the drum:

441_wr_33462.png

Also, I am building a second, less colourful version:

511_wr_33473.png

Functions are identical to first attempt. I mainly did some cleanup on he chassis. Manual control for the drum has been swapped sidewise. The lower part of the cabin isn't done yet.

(I would prefer to get a drum in white or yellow instead of dark(earth) blue.)

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That black version has a nice apparel, looks real heavy-duty. Somehow it looks bigger in this color. Nice work sofar, looks like you've been able to fully reverse engineer this model! I like the little tweaks and additions too, especially the one-direction switch with the wormgear, way better than a ratchet imho!

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Posted (edited)

I am quite happy with the compact setup:

525_20200708_101004.png

Gear 'box':

527_wrn_200705_172111.png

I think that the gear ratio towards the drum is OK: I get 1 revolution per 1.2 m (4') travel. This should be sufficient to demonstrate the principle *). From the video review just posted to the main topic it seems to be 'faster' there.

However, using of the worm gear comes at a cost: When direction is changed between forward and backwards travel it takes ca. 75 cm (2.5') distance before rotation starts.
I calculated that this could be reduced to 45 cm if the new differential (from 42109) would be used instead (because of 28:12 gear ratio)

 

*) I don't think that the 1M beams will be stting in a while ;-)

Edited by anyUser
gear box picture added

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Posted (edited)

This should be small enough to fit into the gear box area of the original set:

914_20200708_133941.png

(Top view, first rear axle on the left, front of chassis to the right,

all red (axle)pins indicate temporary connections that may be used further)

916_20200708_134030.png

(Bottom view, first rear axle on the left, front of chassis to the right)

Edited by anyUser

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This represents the gear box from 42112 truck as far as I recognized from early review videos:

951_wrn_200709_120656.png

This is my current solution to the ratched (the yellow bit inside) mechanism:

921_wrn_200711_102603.png

(top view)

923_wrn_200711_102639.png

(bottom view)

Implementation to my chassis mod:

927_wrn_200711_142512.png

There is no lag for the drum rotation is direction is switched from backward to forward. My setup now has 1 full rotation for each 50 cm of travel which I consider (too) 'fast'.

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643_wr_33512.pngI am done for the moment. Now I would need the drum pieces to test-drive my version. I would like to have those in either white, yellow, or even grey colour without printing:

604_wr_33495.png

- drum rotating only one direction (mixing) when driving
  a) wormgear version: drum also rotating when driving backwards
     setup is inspired by https://rebrickable.com/mocs/MOC-44634/2in1/simplebutclever-2-only-one-direction 
  b) "Ratched" version: drum not rotating when driving backwards

- smaller turning cycle by improved steering angle
- axle width is smaller by (ca.) 2 studs, e.g. wheels are not protunding from chassis
- cabin can be tilted forward
- funnel to fill the drum 

Images:

614_wr_33514.png

636_wr_33530.png

643_wr_33512.png

691_wr_33547.png

I can't decide on the colour for second truck: I am missing the proper colour of 3x3 half beams with curve for those schemes that I would like to build...

 

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4 hours ago, anyUser said:

691_wr_33547.png

Seeing that bottom view, I wonder how easy it would be to make the two rear axles pendular. It would require some reinforcements in the frame, but gives you the illusion of suspension on the rear wheels.

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Posted (edited)
On 7/20/2020 at 3:56 PM, 1963maniac said:

Are you going to be making building instructions?

I may consider it after test with drum installed.

On 7/20/2020 at 4:23 PM, Cumulonimbus said:

Seeing that bottom view, I wonder how easy it would be to make the two rear axles pendular. It would require some reinforcements in the frame, but gives you the illusion of suspension on the rear wheels.

I don't think that suspension on a model of this scale is 'necessary'. I prefer having a fake engine.

I am not an expert on suspension. I have currently assembled two set with pendular suspension: 8284 and 42030 (8265 hasn't?). There is more space for realisation. As you can see the two rear axles are next to each other. Thus there is little option - without bigger changes to the drive train - to have anchor points. The last axle alone could easily be done.

For the other one:
Range would be severely limited as the drive for the drum is passing just over the differential. I have mounted gear support to the 5x7 frame - these could be attached to the upper framework instead.
It could be feasible if you omit the differential for these wheel to put the support to the middle of the frame. Engine and drum would be driven by last axle only.

If you would like to have suspension on a concrete mixer, check out the MOC by desert752

Edited by anyUser

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The cement drum is a really heavy weight that has to be moved.

I did some test driving with the drum on both versions: Neither of them could turn it.
Gears are slipping:
a) 12 tooth half bevel to 12 tooth bevel
respectively
b) 8 tooth gears that form the ratched
To fix either of them I think I have to add bracings to hold gears in place. As these are deep within the chassis I may have to redesign the whole gearbox.

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I have a cool mod by using the fender elements from the Lego set 42098 and use them on my Lego set 42112 and add a grille and add a few Lego Power Ups and you get this!!!!! 

 

50383768483_e75de2d2da_k.jpgLego Technic 42112 fender mod by victormendoza_jr, on Flickr

https://flic.kr/p/2jLjkFc

50384618397_9c2ef0f0cd_k.jpgLego Technic 42112 fender mod by victormendoza_jr, on Flickr

Man, I do miss this website!!!   I'm back!!!!  

Edited by sirslayer

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