MOCpages : Share your LEGO® creations
LEGO models my own creation MOCpages toys shop NYM's UnimogTechnic
Welcome to the world's greatest LEGO fan community!
Explore cool creations, share your own, and have lots of fun together.  ~  It's all free!
NYM's Unimog
Hello All! Back with another model. Introducing NYM's (Not Your Mother's - in reference to it being so dirty!) Unimog. Although it looks very similar to the 8110, I assure you it is not. Powered by my three cylinder Lego pneumatic engine (Thanks Alex! @ lpepower.com), this thing is a beast. The chassis is very much minimized from the original 8110 model to decrease weight and increase flexibility. Let's look at the specifics....
About this creation


Stud length: 62 (including winch)
Width: 22
Weight: 1956 grams (tires are really heavy but worth the weight)
Piece count (est.): 1850

Here are some pics without the canvass covering. As can be seen, the pneumatic engine is a beast. Estimated to run @ 1500 RPMs @ 60 psi, this thing needed to be geared down quite a bit to be able to function. Otherwise, it would be too fast and every little bump and drop would break axles, steering, etc. Additionally, if not gearing this baby down enough then hills, rocks, etc. would be impossible b/c the pneumatic engine would stall.






Here is a picture of some of the gearing. However, not all.



As can be seen I had to double the gears on some places to enhance strength. This I did wherever there was a 8 tooth gear powering a 24 tooth gear, b/c the stress was greatest at these junctures. This helped give the NYM Unimog crazy torque.


Using Sariel's gear calculator I estimated that I geared this monster down 1:35! Yea, I know, that sounds ridiculous but that is the gearing. Again, this may sound like ridiculous gearing but let me give you some numbers. Many know how fast the Lego 9396 runs (very slow) so we can use this, and my own rock crawler as an example. Lego 9398 uses two large PF motors, with run @ 390 rpm (assuming no load). My own personal crawler uses two XL motors that run at an estimated 220 rpms (no load). The 9398 is geared down 1:6.5, and therefore, again assuming no load, the 9398 runs at 390/6.5 = 60 rpms. My crawler is geared down 1:5, and therefore runs @ 220/5 = 44 rpms. The NYM Unimog, although running at 1500 rpm @ 60 psi, geared at 1:35 runs at 1500/35 = 42.85 rpms. Now, obviously something is off here because as can be seen in the videos, the NYM Unimog is truckin' much faster than the 9398 or my own personal crawler (which is really slow, check out the video below):



So what gives? Here are a couple of theories: (1) Alex at lpepower.pl is wrong. The engine is not really moving that fast at 60 psi. That was my first thought. I do not own a speed computer, so I can’t calculate it myself. My second thought was; Alex is never wrong. He is a genius. And so I threw that theory out fast. (2) Second theory: Because of the awesome power of the pneumatic engine, when under a load, the rpms do not really differ much from when there is no load. So, in other words, the speed of the engine, at 6 bars (60 psi) is really 1500 rpms, not just the resting rpms (no load). We all know that the figures obtained regarding the LEGO motors, although true, are all under no load, and when placed under a load can change drastically. So, although the speed of the L PF motor is ~390 under no load, under a load it is more like perhaps half of that, ~ 200 or so. So the 9398 is really moving perhaps as something like 200/6.5 which is just under 31 rpms. Much more likely. My crawler, assuming the XL PF motors run at half their no-load speed (when under a load) would run at something like ~22 rpms. Again, much more likely. Last thing I will say… admittedly, I never even, at any time in the video provided below, ran my pneumatic engine at full power. The highest psi I ever used as around 45 psi. Already, at 45 psi I was snapping axles and tearing up gears. Truth be told, 1:35 is not enough. The model is still too fast, and I could probably gear the sucker to something like 1:50 and be fine speed-wise. It ran up several hills and rocky places too fast when I tried giving it all 45 psi. Perhaps a project for the future.

This thing is also equipped with full steering, a winch, and a clutch. When coasting, I found that the forward inertia was indeed too much that if a clutch were not installed, broke and twisted many axles. I went through several axles before deciding that I needed to install a one-way clutch.





Here are some more pics out running and muddin’ – as mentioned, this thing gets dirty!

















Proof the NYM Unimog was here!!



Below is a video that shows the thing running. A couple words. First, just some harmless running in the garage. Nothing fancy. But what can be seen here is the speed. Still…. Too fast at only 45 psi. Second, when I went mudding it worked great. Went through some pretty deep muddy water fine. Again, lots of popping and snapping, but that is just a testament to the power of the engine. Finally, I tried to get it into something really funky. Didn’t work. Engine stalls for just a hint of a second before wearing through the gears. The engine is too dang powerful for LEGO elements. Its kinda cool that in the video you can literally hear the engine wearing right through the gears. I may have to make a visit to the brick machine shop (on bricklink). Enjoy!



*** New update***

Here are some new tires I just got. Huge.... also fit with a hub that I made that automatically has a large gear build in. Looks like I will be doing some more modifications!








Comments

 I like it 
  June 29, 2015
Very informative and useful writeup, thanks.
 I like it 
  June 24, 2015
I'm really glad somebody took the time to do this, as I've always been curious about a pneumatic trial truck but never had the patience or skill to make my own engine. (And now that I do, my parts are otherwise occupied!) Your model seems about as polished as the concept can get, and it performs really well! It must be nice to go through the water without worrying about 30 bucks worth of XL motors getting wet. :P
 I made it 
  January 8, 2015
Quoting Jeremy McCreary Fabulous Unimog mod -- both functionally and aesthetically. Dope-slap moment: Why did it never occur to me double up gears on high-torque axles? I know nothing about LPEs, but I do know that hard data on RPMs under load taken at some convenient point in the drivetrain would help a lot in sorting out torque/power/RPM relationships in specific LPE-powered MOCs like this one. The hand-held laser tachometer I got for $12 on Amazon became instantly indispensable my own work with motorized MOCs. It's much more robust and versatile than the LEGO speed computer at a fraction of the cost and even came with a nice supply of reflective tape. If generic torque-RPM and power-RPM curves have been worked out for LPEs, as they have been for DC motors, RPM measurements would have a good bit of predictive value WRT the best gearing for a particular application -- e.g., mudding vs. speed on hard level ground.
Wonderful comments Jeremy. Yes, I need to purchase a one of the tachometers you speak of. Without it though, I do know that for mudding or climbing, this vehicle is still too fast. As I show with the new rims and tires above, I hope to correct this problem with additional gearing in the hub. Added torque will only help the model run through mud and climbing etc. But the main thing that I need to do now is strengthen the drivetrain so that it does not snap so easily. That is my main goal at the moment.
 I like it 
  January 7, 2015
excellent!!!
  December 30, 2014
Fabulous Unimog mod -- both functionally and aesthetically. Dope-slap moment: Why did it never occur to me double up gears on high-torque axles? I know nothing about LPEs, but I do know that hard data on RPMs under load taken at some convenient point in the drivetrain would help a lot in sorting out torque/power/RPM relationships in specific LPE-powered MOCs like this one. The hand-held laser tachometer I got for $12 on Amazon became instantly indispensable my own work with motorized MOCs. It's much more robust and versatile than the LEGO speed computer at a fraction of the cost and even came with a nice supply of reflective tape. If generic torque-RPM and power-RPM curves have been worked out for LPEs, as they have been for DC motors, RPM measurements would have a good bit of predictive value WRT the best gearing for a particular application -- e.g., mudding vs. speed on hard level ground.
 I made it 
  September 7, 2014
I can provide a reference if you want. They are RC tires, which, if you buy the right size, fit LEGO rims perfectly.
 I like it 
  September 7, 2014
This is really cool man.Awesome job! Where you get that tires?
 I like it 
  August 26, 2014
Best of Lego engineering there!
 I like it 
  August 25, 2014
haha£¡I'm first one. wow!~this is very cool,You're success! I like it.
 
By Nirds forprez
Add to my favorite builders

13
people like this. See who.

3,856 visitors
9 comments
Added August 25, 2014
More from Nirds
More across MOCpages
 


LEGO models my own creation MOCpages toys shop NYM's UnimogTechnic


You Your home page | LEGO creations | Favorite builders
Activity Activity | Comments | Creations
Explore Explore | Recent | Groups
MOCpages is an unofficial, fan-created website. LEGO® and the brick configuration are property of The LEGO Group, which does not sponsor, own, or endorse this site.
©2002-2017 Sean Kenney Design Inc | Privacy policy | Terms of use