I got a lot of comments stating that some of the mechanisms are fragile or useless. Here's just a reminder that the main purpose of this video is to learn something about mechanical principles, not to never use gears again. Of course it's better to use bevel gears than #3, but #3 just looks cool :) For example #2 and #4 are even useful, but that's not why I made this video Enjoy watching :)
I wouldn't say its useless, something like the pantograph would be pretty useful to replace a lot string of gears, since the lego technic chain is terrible and constantly snaps under any load.
well the reason you got so many comments is that you worded the title of the video as if you were presenting a usable alternative to gears. a better title might've been "interesting alternatives to gears in lego"
I'm sure I saw somewhere that an early differential used on early hotbulb motors for agri equipment used a principle very similar to #3 and was very reliable.
This is called a "linkage" in engineering context. The issue I saw with the second example was that the force on the linkage was in the same direction as the friction fit of the parts. It's prone to pull itself apart under load.
#2 is mechanically overdetermined (with plastic it works, but don't try this with anything that is stronger). If you run the numbers you'll find that the driven end of the rod is not describing a circular path and the angular velocity also is not constant anymore (if the wiggle point in the center is fixed). If you got 2 circles on each end the crossing point of the wiggling strut vs the connection line of the two axis will move ALONG the axis. PS: yes, that is experience talking, I tried to use something like that and learned the hard way 🙄
You're completely right, in this case the gap is big enough for some wiggle room, but you can't apply that mechanism to something that has to be precise (it's not constant velocity either). That's why I included #4, which is mechanically correct but has more moving parts
I don't suppose this is like U-joints, where using a second one would correct back to constant angular velocity? Also, I wonder how they got around this with steam locomotives, where one drive axle was driven by the engine and drove the rest using rods connecting the drive wheels.
@@SkorjOlafsen _"using a second one would correct back to constant angular velocity?"_ No (based on how the path of the driven endpoint is being distorted). _"how they got around this with steam locomotives, where one drive axle was driven by the engine and drove the rest using rods connecting the drive wheels."_ No pivoting is happening there. This mechanic turns the turning direction of the driven wheel vs the driving one.. for a steam loco they all turn in the same direction due to the connecting bar keeping it's orientation (no pivoting).
@@joansparky4439 they also had the other side of wheels offset by 90 degrees as well as counterweights in the opposite side of wheels, (so the left side rod was at the lowest/highest while the right one was on the most backward/forward position) you see the same thing in combustion engines with pistons and crankshafts although with those they also use full 180
I have seen several of these on older (often steam) farm equipment. This makes sense as back in the day many of these would be easier to fabricate or repair with common farm tools and materials, whereas most farms (then and now) lack the capability to manufacture precision gears which are perfectly balanced. For low rpm devices than can stand wide tolerances, these would be fantastic, and were. I actually had the opportunity once to run a steam driven water pump that applied 5a/5b.
keep in mind most of these mechanisms would have more linear inertia and vibrations than their gear counterpart due to linear motion so its up to your design to compromise into either fully rotary like gears, or with linear mechanisms as such.
A couple of these look useful if you want to stop torque twisting axles too easily. The tiny pantograph looks like a cool mechanism for all sorts of applications. I might try a few things out.
Plus iirc it works at any angle, and iirc that also means it works for changing the angle while it's rotating if you use some sort of connection that can change its angle.
@@Sokail87 Yeah, if the corner pieces were replaced with a piece that can bend, then the resulting linkage can work at any angle (even if one or both sides are moving within a certain plane)
This is really cool!! I think it could be even cooler if you reduced the gear ratio of the initial motor so we could see it moving a lot slower, but still very cool.
Amazing content, thanks a lot for your vids! This one is longer then usual it seems, a nice surprise :) Would love to hear more of your commentary on pros and cons of those designs and where you can use them Edit: also, could it be possible to use angled axel joints in the bevel var.2? Would it remain as robust as the 90 degree one?
Yeah, in this case I'd recommend using #2 if you want to create longer transmissions without gears and less backlash, or #4 if you need something more robust than gears... It is possible to use angled axle joints, and the cool thing about this one is that you can also use that principle to make a constant velocity universal joint: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-nYLRZBvCwPE.html
1 - Good ol' chain drive. Very robust and efficient, likely the best alternative to replace a long gear train. 2a - It's okay but a bit overcomplicated for the task. 2b - Slimmer, simpler looking than 2a. Looks way better, it might fail under load though (the rounded T join may be pulled off the end of the axle) 3 - Very creative! Also makes me unreasonably upset. It's a great demonstrator of translation-rotation conversions, but it's super inefficient and fragile. You would never want to use this thing to power any machine, ever. 4 - This one looks fun. You can probably attach things to the moving joints to do god-knows-what. 5 - This looks very cool. And dangerous, for me. Don't let it anywhere near long hair.
Yeah, let's not talk about the usefullness of #3 :) Even #5 has a high friction. The only useful ones except #1 are probably #2 and #4 because #2 doesn't have that many moving parts and #4 is pretty robust
@@in1 #5 is a simple CV joint that just doesn't flex. If you replace the 90* connectors with swivel joints, you can aim the thing in all sorts of different directions, and it will work just fine
@@kuhljager2429 #5 is definitely pretty good, all though under really heavy loads you might run into some torsion issues. A few reinforcing rings and maybe some springs or a pusher plate to keep the sliders from getting out of sync under strain would probably be enough to make it take a beating though. You just want to keep the amount of unsupported travel to a minimum for best results.
I wonder if it would be possible to replace the two 60483 pieces in #2 and #4 with liftarms of different lengths, to reproduce the effect of gearing up or down. And if so, how the ratios between different liftarm lengths would work.
Remember, Friends. The only one here that's actually good in the real and industrial world is the pantograph. Sometimes the beam, If you really do need it. The others aren't smooth and create unwanted stress because of it. Even the beam has it's flaws, Being that it has to rub against the middle post. Friction is the machine killer. . . . Though I will admit, The transmission has always been amusing to watch.
God, as an engineering student seeing this shit is always awesome!! Knowledge in so many fields can come from and go to so many places. Always keep an eye out for nifty things and ideas, you never know when or where you could use them!
I will keep in mind the beam/axle drive extension. Often I want to bypass the usage of many gears but chains present too much friction. This looks somewhat more efficient, and the inherent fragility present in the assembly could almost act as a fail safe against excess torque in the system.
#4 is based on a Pantograph, which is actually also being used in different real life applications A modified version of #5 is used in constant velocity joints
Maybe the first one (use a bigger/smaller tread wheel on one side), but the best option would probably be a belt. I built it, but forgot to include it in the video :)
You could use the first mechanism from this video: ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-1WeNkikqeOs.html combined with a changeover catch (part 6641) to archieve the same effect
A bit surprised a pair of bevels driving a crankshaft didn't feature although that is a boring design, it's essentially what you'll find under most cars. Belt drive deserves a mention as a self-tensioning version of the featured chain drive (treads). Also, pretty sure the beam driven systems could be further simplified by running the drive beam directly between both output cranks, with the cranks indexed to the same position. But running it across with the 90° angle looks so much cooler.
Of course bevel gears are pretty common, in this case I didn't include it just because the video title was "Alternatives to gears" I actually built the belt drive and wanted to make it something like #1b, but somehow managed to forget recording it The beam has to be angled in this case, because when you just connect them without something in the middle, the other end will just oscillate because you don't force it to turn over. When adding another crank in the middle, it will just get stuck in most cases.
#1 ofc treads, but not as a power transmission #2 Steam Locomotives #4 Pantographs are actually a real life thing to copy movement, you can look it up on wikipedia #5 Not really real life, but it's the same principle as a "constant velocity joint“ which is being used in real life
@@in1 just looked at the pantograph thing, very interesting Video was very interesting too! I think it would be good to add a bit where the motor is going slower so we can see the mechanisms moving in slow motion
For the first one, the bar covered in gears, the alternatives all have sliding between parts which may cause them to wear. A better solution may be to replace the centre piece with another rotating bar, like the ones at the ends, so the whole thing works like a set of old train wheels, so three bars coming out from the shaft, all connected to a single long bar, so if you rotate any of the shafts they will all rotate.
I would love to see these stress tested to failure for a few reasons: 1. Capacity: knowing how much load each can take both nominally and at failure to know which are capable of the highest load and also very high rpm. 2. Mode of Failure: seeing what broke will allow you to possibly compensate and increase capacity depending on the mode. 3: unforeseen effects at high load, such as massive vibration, heat generation, skipping of cycles, or warping of the module leading to failure or inefficiency.
the Thing about Gears is that you generally don't get the osilation that beams and other horisontally or vertically moving mass gives so unless you are trying to make your mashine slither about or jump I would sugest using gears for most drive trains. not to meniton 99% of the time a gear asembly is more compact then most of these alternatives.
Great video. Some cool concepts are shown. I am only worried about some of them having problems with friction. For example these moving bars for wear out
I just lifted your thumbprint from a still of the black beam at 4:04. Now all I need to do is create a fake thumb, steal your phone and I'm in! These are cool. I'd like to adapt them to Lego Trains for pistons and that. Shameless plug of @ebsbx which has a couple of Lego train vids, R/C cars and Soapboxes.
Not really, because technically it's not 100% right, so you can use it in Lego which has a big wiggle room anyways, but not for real life applications. A variation of #4 is being used in real life, though (Wikipedia: "Pantograph"), maybe even in vehicles
This is so cool. very interesting and unique ideas. Keep up the great work! You give me lots of content to binge while I procrastinate on 3 projects due tomorrow 👍
#2 (Or rather a similiar arangement of two crankshafts) where actually used in German mines before the spread of steam engines to transmit power over a cople fo hundred metres from waterwheels to the mineshafts where the power was use to drive pumps or elevators.
I think it’d be far more useful to demonstrate a use-case as to why the alternative would be used. I work in mechanical engineering and one of the few things I’ve struggled with is teaching the new hires what they’re looking at
I have recently returned to legos ( after a 30 year break). This looks absolutely amazing. Thanks for giving me a taste of what can be done. The last one was mesmerizing. Is there a way to get the motor to run more quietly. My electric car can go 80 MPH and make less noise :)
I think it might be interesting to build something that has decorative gear alternatives that are connected to the actual working gears, so that it looks like the decorative mechanisms are doing the work.
Those pantograps would probably make a nice quadroped walker robot if you add some static legs to it and double the mechanism. It had a distinct up&down stroke on an angle for each end, perfect for legs really.
Yeah I tried around with it a little bit, but the scrapped the project because the walker wasn't really compact at all. Maybe I'll continue trying and upload a video about it when I get it to work, not sure...
Question about 2a and 2b, what is the point of the guide in the center. Isn’t the beam already restricted to moving like that without it? Just wondering if I’m missing something. Either way, beautiful video I like it
In this case the audio was broken and in most cases it isn't that much (you don't hear anything when you slide an axle through an axle hole), so it would have basically the same effect when you mute the video
