Sariel

4-Speed RC Sequential Transmission with Stepper Shifter

Recommended Posts

Wow! This is really nice. I may have to find a need to use this.

Thanks for doing this?

Andy D

Share this post


Link to post
Share on other sites

In years to come when petrol gets low and the americans stop invading the middle eastern oil fields all cars will be powered by hydrogen fuel cells with electric motors, these cars will need reliable gear boxes, there is a rumour of a constant variable transmission that can handle the high torque of electrical motors and seamlessly go to any ratio that is controlled by a second small motor.

Share this post


Link to post
Share on other sites

In years to come when petrol gets low and the americans stop invading the middle eastern oil fields all cars will be powered by hydrogen fuel cells with electric motors, these cars will need reliable gear boxes, there is a rumour of a constant variable transmission that can handle the high torque of electrical motors and seamlessly go to any ratio that is controlled by a second small motor.

A bit off topic but,

There are already bulletproof CVT:s on the market, the big issue is not regarding reliability but efficiency. Just look at modern tractors, almost all of them use some kind of CVT. The simplest one I know of is the one made by AGCO (used in Fendt and Massey Ferguson tractors). It only consists of a hydraulic pump and a hydraulic motor both connected to a planetary gear set. Here's a video explaining it all, although a bit simplified

The reason they work here, I think, is that a tractor consumes quite a lot of fuel under load and if you're able to stay in the sweet spot of the fuel consumption map regardless of the ground speed you will increase the overall efficiency despite increasing the losses in the transmission.

The thing is that these transmissions only work for lower speeds, to get a transmission that works for speeds from 0-200 km/h you would need a different solution not using hydraulics. A car, unlike a truck or tractor, only uses a very small part of its power when running constant speed, even in high (legal) speeds. No matter what you do there's no point in the fuel consumption map of a combustion engine at low load that gives you a low fuel consumption per horsepower made. AFAIK, subaru are playing around with a belt-driven CVT combined with a petrol engine and there might well be some other company doing this.

On the other hand, if we're talking electric motors there's the well hated (at least by petrolheads) Toyota Prius which uses a gearbox similar to the Fendt Vario. They have just switched out the hydraulic pump and motor with electric motors connected to the battery pack. Now you can use the CVT in smart ways to either transfer power to the wheels or starting the combustion engine to charge the batteries.

If you want to discuss this topic further I suggest we start another topic. I might also have some inputs on hydrogen and fuel cells, moslty why they might not be "the furure".

Edited by Klirre

Share this post


Link to post
Share on other sites

A bit off topic but,

There are already bulletproof CVT:s on the market, the big issue is not regarding reliability but efficiency. Just look at modern tractors, almost all of them use some kind of CVT. The simplest one I know of is the one made by AGCO (used in Fendt and Massey Ferguson tractors). It only consists of a hydraulic pump and a hydraulic motor both connected to a planetary gear set. Here's a video explaining it all, although a bit simplified

The reason they work here, I think, is that a tractor consumes quite a lot of fuel under load and if you're able to stay in the sweet spot of the fuel consumption map regardless of the ground speed you will increase the overall efficiency despite increasing the losses in the transmission.

The thing is that these transmissions only work for lower speeds, to get a transmission that works for speeds from 0-200 km/h you would need a different solution not using hydraulics. A car, unlike a truck or tractor, only uses a very small part of its power when running constant speed, even in high (legal) speeds. No matter what you do there's no point in the fuel consumption map of a combustion engine at low load that gives you a low fuel consumption per horsepower made. AFAIK, subaru are playing around with a belt-driven CVT combined with a petrol engine and there might well be some other company doing this.

On the other hand, if we're talking electric motors there's the well hated (at least by petrolheads) Toyota Prius which uses a gearbox similar to the Fendt Vario. They have just switched out the hydraulic pump and motor with electric motors connected to the battery pack. Now you can use the CVT in smart ways to either transfer power to the wheels or starting the combustion engine to charge the batteries.

If you want to discuss this topic further I suggest we start another topic. I might also have some inputs on hydrogen and fuel cells, moslty why they might not be "the furure".

Cost is going to have to take a back seat on this, there is no point having cheap power when no one can breath and has died, don't forget money is a illusion to make not so clever people work their entire life for nothing while the rich laugh at them, take from greedy people and never feed them.

Hydrogen is the future, there is no other way really, we are going to need good gearboxes for electric motors and its down to people like sariel to make them, unless your born rich you have no way to express your talents in a practical way, unless you get some lego that is.

Share this post


Link to post
Share on other sites

don't forget money is a illusion

Guess I should let my landlord know I'm paying my rent with an illusion.

Can we get back on topic please?

Edited by Sariel

Share this post


Link to post
Share on other sites

Guess I should let my landlord know I'm paying my rent with an illusion.

Can we get back on topic please?

You could try, he will either check into the nearest mental asylum or stare at you with a blank expression, however he will most likely check you bills to make sure they are not counterfeit.

Share this post


Link to post
Share on other sites

Great work Sariel, the performance is very impressive. Now I'll have to get some of the new smooth axle joiners.

Now a lot off topic:

There are already bulletproof CVT:s on the market, the big issue is not regarding reliability but efficiency.

The thing is that these transmissions only work for lower speeds, to get a transmission that works for speeds from 0-200 km/h you would need a different solution not using hydraulics. AFAIK, subaru are playing around with a belt-driven CVT combined with a petrol engine and there might well be some other company doing this.

CVTs are used in plenty of cars currently on the road. https://en.m.wikipedia.org/wiki/List_of_automobiles_with_continuously_variable_transmissions

In cars, they are often more efficient than manual transmissions. They work well at all speeds, but are less reliable in the long run than automatic (and possibly manual) transmissions.

Share this post


Link to post
Share on other sites

Now a lot off topic:

Sariel already asked to get back on topic, so let's not derail this topic....again.

Share this post


Link to post
Share on other sites

@Sariel, thanks for sharing this interesting piece of work. I have the following question: A much smaller motorizable stepper + 4-speed sequential gearbox has been posted by Attika a few days ago. Can you elaborate on the main differences between your solution and Attika's solution?

Edited by Didumos69

Share this post


Link to post
Share on other sites

Can you elaborate on the main differences between your solution and Attika's solution?

Um, I'm not sure why I should, seeing as I barely know Attika's solution. These are two mechanisms that do essentially the same job quite differently, I thought it's plain to see. My design is a development of a gearbox I've made last year and it was made possible by the new smooth 3L axle joiners from the 42056 set. The differences I can see at a glance are many, e.g. my solution doesn't use a PF Servo motor nor steering links, and a single rubber band instead of two. I'd also say both are pretty much the same size, with mine being taller but narrower.

Edited by Sariel

Share this post


Link to post
Share on other sites

Although this gearbox is working well but it will make any thing its connected to less efficient, heavier plus far more can go wrong, I don't see the point of making something more complicated to point of it being almost useless.

Share this post


Link to post
Share on other sites

Um, I'm not sure why I should, seeing as I barely know Attika's solution. These are two mechanisms that do essentially the same job quite differently, I thought it's plain to see. My design is a development of a gearbox I've made last year and it was made possible by the new smooth 3L axle joiners from the 42056 set. The differences I can see at a glance are many, e.g. my solution doesn't use a PF Servo motor nor steering links, and a single rubber band instead of two. I'd also say both are pretty much the same size, with mine being taller but narrower.

Thanks. I consider you as someone knowledgeable when it comes to LEGO gearboxes and was just being curious about your thoughts on Attika's approach, which also combines a stepper with a 4-speed seq. gearbox.

Edited by Didumos69

Share this post


Link to post
Share on other sites

Although this gearbox is working well but it will make any thing its connected to less efficient, heavier plus far more can go wrong, I don't see the point of making something more complicated to point of it being almost useless.

The same can be said about any mechanism whatsoever. Why use gear wheels at all, they make things less efficient? FYI I have successfully tested earlier version of this gearbox in my 3.2 kg heavy Land Rover Defender and nothing went wrong. Some people want to use gearboxes and see need for them, even if you don't (try thinking of a gearbox as of European Union).

Edited by Sariel

Share this post


Link to post
Share on other sites

Would a L motor work for shifting the driving rings with the ribbed 3L connectors?, and I think it would be possible to improve the profile of it, by rotating the M motor 90 degrees downwards, though it may interfere with the front inputs. I think it would be cool to see a compact dual differential steering system/ transmission package. As I have attempted to mount 2 4-speed gearboxes in parallel( for each track), and they tend to suffer from being too large, or not robust enough, Though I am most worried about 12z gears failing in the differentials of the adder/subtractor under high load.

Edited by Tommy Styrvoky

Share this post


Link to post
Share on other sites

Speaking of unions, the United Kingdom was the only country in europe not to surrender to or join the nazis in world war 2

So you don't know the history either. You weren't the "only" country pal, Poland didn't surrender or join nazis either, you can climb down your pedestal now. Moreover, British high society was in full love with Hitler, to the point where the video exists of young Queen Elisabeth II happily performing a nazi salute. Sorry to teach you history, someone has to.

Source: http://www.thedailyb...-the-nazis.html

Also, don't miss the fun list of British nazi parties (looks like you had more of these than Germany itself): https://en.wikipedia...fascist_parties

Would a L motor work for shifting the driving rings with the ribbed 3L connectors?

No, it's not the matter of torque, the ribbed 3L connectors simply generate backlash in the shifting mechanism so that the two rings don't shift all the way.

Edited by Sariel

Share this post


Link to post
Share on other sites

Speaking of unions, the United Kingdom was the only country in europe not to surrender to or join the nazis in world war 2, we left europe because the eurotrash is getting unsightly and the nazi merkel bitch keeps letting syrian scum in.

Needless to say that comments like these are NOT acceptable on Eurobricks. Don't do that ever again.

Share this post


Link to post
Share on other sites

This discussion has nothing to do on Eurobricks and has to stop (if Jim's post wasn't clear enough).

This topic is about Sariel's sequential transmission, so please stay on topic. Thanks.

Share this post


Link to post
Share on other sites

No, it's not the matter of torque, the ribbed 3L connectors simply generate backlash in the shifting mechanism so that the two rings don't shift all the way.

speaking of torque, how easy is it to disengage the driving rings under high torque, is that a potential issue? Or does the changeover catches keep it in place? I know you showed the operation in the video under stress, but I mean like serious stress for TTs, like all wheels can't slip. or the case for tracked vehicles, where slip isn't possible.

Edited by Tommy Styrvoky

Share this post


Link to post
Share on other sites

Well, the same type of gearbox, but with ribbed connectors worked fine without disengaging in my 3.25 kg heavy Land Rover Defender. I haven't had the chance to test the smooth connectors in similar model yet.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Recently Browsing   0 members

    No registered users viewing this page.