[TC26] Arctic Explorer Truck

[2GodBDGlory]

[EDIT: Final presentation of the model added further down]

Well, choosing a topic for this contest was challenging!

The main issue was my very limited supply of the required orange and white pieces, which is really a self-induced problem because I don't feel like buying more parts! Anyways, I started going down the list of models seen in the Technic and city subthemes, with an eye for which types of models required relatively small areas to be covered by the primary color! I decided that the best options would be a helicopter, a snowmobile, or a snow-groomer type thing. I have been itching to build a helicopter, but the small scale imposed by my part collection wouldn't let me do much interesting, so I scratched that off. The snowmobile could be cool if I could make one with good performance, but I've tried before with stock Lego components, and didn't have much success, so I moved to my last option. This was mainly inspired by these two City sets (The latter of which I'm borrowing a name from):

Spoiler

I assume it's some sort of snow groomer they're modeling, but the important thing for me is a relatively small cab to build in body color, a cool crane arm, and a tracked chassis, which is something I've never done too much with.

With that in mind, I started thinking about functionality. Being limited to four motors, it seemed natural to allocate two motors two driving the two tracks, for reliability and power. (as I type this, my brain remembers subtractors. Subtractors are cool! I should build a subtractor!) (Anyways, subtractor or no, it'll be two motors for that). That leaves two other motors, and plenty of other things to control! With that constraint, I decided I should have one motor shifting a RC distribution gearbox to allow for multiple functions, and then use the fourth one to actually run those functions. The primary thing I wanted to motorize, though, was the crane arm, which needs to have rotation, at least two articulated sections, and hopefully a rotating hook to allow for fine control of loads. This requires three functions through a turntable, which is, of course, essentially impossible to do mechanically. I thought about mounting the whole gearbox on top of the turntable and just running shifting and power through the turntable, but that sounded bulky, and then rotating the turntable would end up shifting functions, which isn't ideal. In the end, I scraped up an old idea from some dark corner of my mind, and built this:

It's a sort of sliding-gear 3-output distribution gearbox, but built inside of a turntable, so that it can be shifted and driven from the bottom, while having three outputs on the top. It might be a bit hard to picture, which is why I've got the video above to explain how it works.

Anyways, that's all I've got done so far, and there's a lot of questions to answer yet, but I'm quite pleased with this concept, which should make for an interesting and functional crane arm. The big question, which I didn't really think until now, is how I'm going to power turntable rotation, which isn't one of the three functions in the gearbox. Of course, I also have been thinking about how I can control any front blade, so maybe a secondary distribution gearbox? It could be tough to control two gearboxes with one motor, though. Anyways, I'll be pondering these questions!

Edited November 29, 2023 by 2GodBDGlory

[msk6003]

Sliding transmission on turntable is awesome idea! Now we can make compact(At least smaller and reliable than this) 3 function through turntable!

And even use longer axle and sliding system  it will work it limitless function through turntable.

[Alex Ilea]

This sliding concept alone can win the Lego Technic innovation of the year!

[Jurss]

Yes that conept is genious, but with community voting it won't win :)

[Gumalca]

Nice idea with the sliding transmission! Does it work reliable without jerking or blocking? If I remember correctly in manual models this gear shifting will often block because when two teeth happen to be above each other they don't just slide inside each others gaps.

[2GodBDGlory]

Glad to see some interest in the concept!

9 hours ago, msk6003 said:

Sliding transmission on turntable is awesome idea! Now we can make compact(At least smaller and reliable than this) 3 function through turntable!

And even use longer axle and sliding system  it will work it limitless function through turntable.

Yeah, I remember seeing that 3-function design, but it looks very impractical!

You're right, with a longer axle you could have an unlimited number of functions. With this specific design, I was limited to only three functions because I was maxed out with 7L half-stud liftarms, but I'm sure it could be redesigned to have more. You'd just run into more problems with the driving gear's axle bending and skipping gears, especially on the middle positions.

1 hour ago, Gumalca said:

Nice idea with the sliding transmission! Does it work reliable without jerking or blocking? If I remember correctly in manual models this gear shifting will often block because when two teeth happen to be above each other they don't just slide inside each others gaps.

I'm not having any issue with smooth shifting. Multi-speed transmissions would be more problematic than this, because all the gears you're meshing with are mechanically connected, so it might be hard for them to deflect a tooth. In this distribution one, though, all the gears are independent, so they can easily self-center themselves. The bevel profile helps a lot too.

[2GodBDGlory]

I've got a lot of progress done on this model! The main frame is pretty much done functionally--I just need to add some suspension for the tracks and install a battery and IR receivers. After that I'll have to work on the crane arm and front blade and the bodywork.

Anyways, I finished the gearbox, which is now a rather complex system. A PF M-motor first runs a direction-sensitive worm gear gearbox, so that when it drives clockwise it runs one output, and when it drives counterclockwise it runs a different output. These two outputs are two different distribution gearboxes, both of which are driven by a PF L-motor. First the L-motor runs through a normal 4-output distribution gearbox controlled by a wave selector. The four outputs of this gearbox include lifting and rotating the front blade (not implemented yet), and rotating the crane arm's turntable. The fourth of these outputs simply runs into the second distribution gearbox, the three-output unit built around the turntable that I showed in my first update.

So in summary:

• The M-motor shifts the wave-selector gearbox when rotating forwards
• The M-motor shifts the turntable gearbox when rotating backwards
• The first three outputs of the wave-selector gearbox run functions normally
• The fourth output of the wave-selector gearbox runs into the turntable gearbox, which then controls three additional functions
• This makes for a total of six RC functions controlled through the gearboxes

Also, the turntable gearbox is no longer shifted via the 4-bar linkage seen in the original video, but now by this eccentric mechanism:

Spoiler

The other functionality is the driving and steering, which is done through a subtractor, with a PF XL motor being used for driving forwards and backwards, and a PF M motor being used for steering. Because this is a subtractor system, we've got different drive modes:

1. XL only, drive forwards

2. XL and M, drive forwards and steer

3. M only, steer on the spot

It would probably perform better and be simpler with a basic two-motor drive system with one XL motor on each sprocket, but I've always wanted to build something with a subtractor, and I hardly ever build tracked vehicles, so this was a good opportunity to build one. I'm also using planetary hubs to drive the front sprockets, which provides a nice bit of torque.

Anyways, I think things are going well, and the complicated gearbox has been made reasonably compact, so as long as it proves durable enough to run its outputs, I should be in good shape!

[n8walker]

Nice project, turns out to have a lot of high tech solutions, which I really like. 

Cool, that you use a subtractor drive, which is far more realistic. I used it in some of my tank mocs as well and in my opinion the steering feels much more realistic this way. And if you add a fake engine, it is running properly.

I am going with wave selectors as well for my entry (nothing posted yet) to overcome the 4 motors limitation. How are you going to make sure to rotate 90 degrees? I am going to use the mind storms parts so I can program it that way.

Greetings

[2GodBDGlory]

2 hours ago, n8walker said:

Nice project, turns out to have a lot of high tech solutions, which I really like. 

Cool, that you use a subtractor drive, which is far more realistic. I used it in some of my tank mocs as well and in my opinion the steering feels much more realistic this way. And if you add a fake engine, it is running properly.

I am going with wave selectors as well for my entry (nothing posted yet) to overcome the 4 motors limitation. How are you going to make sure to rotate 90 degrees? I am going to use the mind storms parts so I can program it that way.

Greetings

I'm fairly ignorant about how real-world track systems work--do you think the subtractor is actually more realistic? I would think that a typical system would be a single engine running a hydraulic pump, and then hydraulic motors running the tracks individually, which makes a two-motor system more realistic in that they'd imitate those hydraulic motors, but a subtractor system more realistic in that it'd simulate the single engine running the pump. Either way, this is more interesting, and allows for convenient control!

As for making sure I get 90 degree rotations, I had thought about using PU electronics so I could program it, but while it seemed like it would have a good end result, I wasn't looking forward to the prospect of pairing a phone every time I wanted to testsomething in the build process! (I guess I could have used RemoteBlaBla for that, come to think of it). Because of that, I'm just going to be relying on precise control through a worm gear and watching the selector while controlling it to make sure I end up in the right gear.

[n8walker]

You are right, there are several approaches, and hydraulic drives get used as well, but mechanical solutions have less energy loss, so they get used in fast travelling vehicles. This is, what I used:

https://en.m.wikipedia.org/wiki/Differential_steering#/media/File%3ADifferential_steering_mechanism.png

I agree, with a worm gear the selector should be controllable. Maybe you can even have a little indicator on the outside, to see, which function is engaged.

[2GodBDGlory]

On 11/4/2023 at 10:53 AM, n8walker said:

You are right, there are several approaches, and hydraulic drives get used as well, but mechanical solutions have less energy loss, so they get used in fast travelling vehicles. This is, what I used:

https://en.m.wikipedia.org/wiki/Differential_steering#/media/File%3ADifferential_steering_mechanism.png

I agree, with a worm gear the selector should be controllable. Maybe you can even have a little indicator on the outside, to see, which function is engaged.

Just looked at that now. That is a cool design! I remember seeing someone use it in a bulldozer(?) MOC one time using turntables, and I thought it was very interesting. It's definitely not common in Lego, though!

[2GodBDGlory]

I've made a fair bit of progress since last time!

Mainly I've just built the main bodywork, which is simple, but I think makes effective use of my available white parts. (The LBG 3x11 panels on the bed and the DBG one on the roof will be replaced by white ones that are currently in my Geo Tracker MOC). It's got some LED lights, a roof rack, seats, and a bed area in the rear. I've also got the rechargeable PF battery installed along with two PF IR receivers.

The only functionality added this time is an I-3 piston engine mounted just behind the cab and driven by the XL motor for drive (It was challenging to route drive to it, but I made it work!), and torsion-bar suspension added to the tracks.

Next I'll have to work on the front blade and the crane arm!

[2GodBDGlory]

Well, I think the model is done now! I'd like to take my final pictures in the snow, and while we've had some heavy snows already, it's all melted at the moment, so I'll have to wait a bit longer before a final presentation. Anyways, until then, here's the finished product:

The first thing I added was the front blade, built out of my very small stash of yellow parts. The 5x11 panels I got from the stand for the BMW M1000 RR were extremely handy! Lift and rotation are handled by two of the outputs of my primary distribution gearbox. Lift is accomplished with a small linear actuator, while tilt is done using a worm gear mechanism to push and pull a 5L steering arm to perform the rotation.

The crane arm is relatively typical, with two large linear actuators (controlled from my turntable distribution gearbox) being used to articulate two sections of the boom, and the fourth output of my primary distribution gearbox being used to rotate it.

 The third function in the boom, off my final turntable-gearbox output, is a rotating hook/magnet. I've observed rotating hooks on crane trucks in real life, and always thought it'd be cool to see in Lego, though it seems to be done rather rarely. It's not a complex function, though routing drive through so many joints to get it working was somewhat hard! I also provided a choice between a large hook for lifting loads, and a magnetic attachment, using old Lego magnet elements, to allow it to lift some different objects. (The "hook" not in use can be carried around on the bed.)

The crane is working just  fine, though shifting the turntable-mounted gearbox proved to be more finicky than I'd hoped. (Because of slack, the assembly doesn't move up or down quite a full stud. Perhaps I should have compensated for this by using a 1.5L stroke on my eccentric rather than just a 1L one, but it seems that doing so would require weakening the structure and adding more slack).

After completing the mechanical side, I decided to throw together some accessories to load up the model with, in order to give it a "loaded-for-exploration" sort of look, and to give the crane some things to lift. I started with the fuel cans, fire extinguishers, shovel, and first aid box from the 42069 Extreme Adventure set, then added another crate, a couple spools of rope, a Technic figure (he may get a custom Arctic sticker for his torso), a spare Technic figure helmet, a canister made using the obscure x186 20X gear reduction block for a unique look, a snow brush/scraper clipped to the side, and most notably a model generator, with a V-Twin engine driving a 2x2 round brick via a chain.

 

Anyways, I'm quite pleased with the way the model turned out--the white, yellow, red, and grey color scheme works well for me, and helps my model look like the stuff from the  1986 Technic Arctic subtheme. The functionality was definitely different from what I typically do, and an interesting challenge that way. Mainly, though, I'm happy with the large number of RC motorized functions I was able to achieve under the four-motor limitation!

[Frequenzberater]

Great work with nice technical solutions! 

[pow]

Damn! I feel so small now! This machine is incredible well designed and so good looking!

[1gor]

I like V twin generator. 

[Mikdun]

It ended as great set!

Rotation of the hook is nice alternation from typical functions.

[Seasider]

Great little tracked vehicle and love the complexity you’ve got in your mechanism. The main thing I don’t like visually is I think the crane arm looks too bulky when you consider the length of the vehicle it’s mounted too. To me it looks like a crane from another vehicle mounted on this. But otherwise it’s great

[2GodBDGlory]

1 hour ago, Seasider said:

Great little tracked vehicle and love the complexity you’ve got in your mechanism. The main thing I don’t like visually is I think the crane arm looks too bulky when you consider the length of the vehicle it’s mounted too. To me it looks like a crane from another vehicle mounted on this. But otherwise it’s great

Thanks!

That's a fair point that the crane looks a bit big for the model--I wanted it to have enough range of motion to reach down to the ground, and also up onto the bed, which was a bit hard because the bed ended up being so high. Perhaps I could have figured something with small linear actuators, but I'm something of an amateur at building cranes anyways, so there's probably some other solutions that could have been pursued.

I can't say I mind too much, though! I feel like the whole thing is proportionally a bit odd, with the body being a little high and a little stubby, but I think the effect is more cute/cartoony than ugly, in my opinion.

[2GodBDGlory]

Here's my final presentation!

This model was meant to be as complex and functional as I could make it, within the two requirements of the TC26 regulations, and my limited amount of white parts required for the contest (Well, required if you have even less orange, as in my case). In the end, I managed to pack eight RC motorized functions into a reasonably compact body and the contest's four-motor limitation, through the use of distribution gearboxes.

Aesthetics:

I was pretty happy with how the model looked, especially given how little white and yellow I have! There's nothing really fancy, just a basic body made using the panels I had available, but I think the simplicity works well, giving it a cute/chubby look, in my opinion. The use of yellow and red also helped a lot, I think, especially with making it fit into the color scheme of Technic's 1986 Arctic subtheme. I also added a lot of accessories, including a Technic figure (with a custom sticker on his torso to match the original Arctic ones), the fuel cans, shovel, fire extinguishers, and first aid kit from my 42069 Extreme Adventure, some spools of rope, a canister made from the obscure yet handy x186 gear reduction block, a snow brush, and a little V2 generator with a chain connecting the engine with the generator part.

Spoiler

Functions:

• Drive/Piston Engine
• Steering
• Suspension
• Gear selection
• Gearbox functions:
  • Blade lift
  • Blade rotation
  • Crane rotation
  • Crane lift
  • Crane arm segment
  • Crane hook rotation

 

Drive:

Drive was done with a PF XL motor through a subtractor mechanism, with planetary hubs driving the front sprockets. There was also an I-3 piston engine behind the cab coupled to the drive motor, for that extra touch. Performance was satisfactory, and it was able to make progress in my snow testing, though eventually enough snow would pile up in front for it to have to reverse and try again.

Spoiler

Steering:

Steering was done through the subtractor using a PF M motor. Because I wanted a certain gear reduction, I ended up doing a weird subtractor design, with a 16:20:12:24 ratio on one side, and a 16:24 chain setup on the other side (though with a 12T gear stuck between them at a 1/4 stud offset for a little extra reliability). It was a little weak and slow, but still had enough power to work fine, though steering was a little challenging in my snow testing.

Spoiler

These pictures aren't very helpful, but the first one shows the M-motor, and the second shows a bit of the upper differential used in the subtractor system:

Suspension:

There was a basic torsion-bar suspension on each track, with four bogies able to oscillate. It worked quite nicely, I think, though having both sprockets touching the ground in typical snow groomer orientation did limit how much they could do.

Spoiler

Gear Selection:

Shifting through all the different options for the distribution gearbox was handled by a PF M-motor. First, it ran through a direction-sensitive gearbox using a worm gear (unfortunately too buried for any decent pictures of it without ripping a lot apart!). Using that, the motor would run a 4-output wave selector gearbox or my unique 3-output gearbox built inside of the crane's turntable. The 4-output controlled blade lift, blade rotation, and the crane arm, and then sent power from the fourth output to the second gearbox. The second gearbox controlled both joints of the crane arm and hook rotation.

Spoiler

Shifting motor

 

This is the best picture I have for the direction sensitive gearbox--you can faintly see the worm gear between and below the turntable and 20T gear

 

The basic wave-selector gearbox

 

Spoiler

Woah, you can do nested spoilers! Cool!

Anyways, these are the three positions of the eccentric for shifting through the three functions through the turntable:

 

And these are the three positions for the gears:

 

 

Gearbox functions:

A PF L-motor ran all of the gearboxes, to run all their functions.

Spoiler

The motor

Drive to the crane arm

Blade lift:

The blade was lifted using a small linear actuator

Spoiler

Blade Rotation:

The blade was rotated using a 5L suspension arm moved forward and backward with a lever controlled by a worm gear. This solution was ideal because it wasn't affected much by the position the blade lift was in

Spoiler

Crane rotation:

The crane rotated rather quickly, but not too fast for control. Thanks to the gearbox inside it, and the lack of wires through it, it could be rotated infinitely!

Crane lift:

The first joint in the arm was controlled by a large linear actuator (as was the second)

Crane arm segment:

The second joint in the arm was controlled by a large linear actuator (as was the first)

(Also, do we still call these ones large? I guess nowadays they could be called medium, but that would take some getting used to, and I'd rather just call the larger ones XL)

Crane Hook Rotation:

The hook could be rotated, using one of the most convoluted drivetrains I've built! (Two distribution gearboxes, a turntable, two joints in the arm, and two U-joints at its mounting) There were options for both a standard hook and a magnet one, using an old M-Tron-grade Lego magnet. Both could be used to lift accessories kept on the  bed, and the other one could be kept on the bed when not in use. Hook rotation seems rare in Lego, but it was cool to add, and adds a significant degree of control over loads.

Spoiler

These old WIP pictures are probably the best I've got for these:

Anyways, I'm quite happy with how the model turned out! Performance was acceptable, all the functions worked, and I even liked the appearance! The main downside was the complicated control for the gearbox, which required some finesse to operate, but I think it was a worthwhile compromise to include this much functionality!

More pictures at: https://bricksafe.com/pages/2GodBDGlory/tc26-snow-groomer#

 

[Daniel-99]

A great model indeed! I love how you squeezed all the functions in such a compact build. Lego technic designers should lear from you! Additional appreciation for your presentation!

[Saruzeufel]

Wow! This is brilliant. I thought about building something with a distribution gearbox as well but this is just on a whole new level. To use the shifter motor with a secondary directional mode to have two distribution gearboxes is mervelous... also the mechanism for the turntable is so simple but well thought out... I might have to copy that for a future project ;)

Really well done!

Edited December 2, 2023 by Saruzeufel
typos/ phrasing