Steering mechanism for tight wheel wells?

[stevendejong]

23 minutes ago, gyenesvi said:

the excess of the sliding axle protrudes out of the 8 module long assembly

You could use 18651 (pin with 2L axle) instead of 6553 and 22961 (axle / pin connector hub) instead of 3749 there. Why change that? :)

23 minutes ago, gyenesvi said:

I could actually test this later though..

Very curious.

32 minutes ago, vascolp said:

here it is another version

This looks very sturdy and elegant. Does it steer well? Perhaps the sliding axles are too rigidly kept in place?

55 minutes ago, gyenesvi said:

I guess sooner or later you'll have to order it if you want to build that bus anyway

Sure, but we're testing alternatives here, so I guess it comes in handy to have a lot of Technic lying around. I would order a bunch and then end up with having to try a piece I don't have. :D

Edited July 4, 2023 by stevendejong

[gyenesvi]

32 minutes ago, stevendejong said:

You could use 18651 (pin with 2L axle) instead of 6553 and 22961 (axle / pin connector hub) instead of 3749 there. Why change that? :)

Yeah, I know, it is possible to use that combination, the reason I though I'd change it is because this way the sliding connector has a more stable pin connection with the assembly above it, instead of the axle in the pinhole. But it might not matter at all, it depends on the total weight of the build I guess.

What I'd do is I'd order all the pieces required for these two final alternatives (not that much, and there's substantial overlap) and test out both in the actual body. I'd even test out my variant using double pivots and 4 of these  connectors if you are worried that fixing the sliding axles too much (though I guess that was the point) would hinder steering performance.

[vascolp]

1 hour ago, gyenesvi said:

Ooops, I noticed a problem with my single pivot design.. If one of the pivots is fixed, and the center point moves (say, backwards)...

Yes, that's why I said you needed a gap behind. You see, I tested it IRL and those problems appear immediately… I am not in a Studio mood ...

Your idea of using a  is very good because it inserts the needed gap and avoids horizontal rotation.

1 hour ago, stevendejong said:

This looks very sturdy and elegant. Does it steer well? Perhaps the sliding axles are too rigidly kept in place?

As I said before:  it is not completely smooth, there is some resistance when you start to steer… I think because the axles do bend a little when you start to steer. But in fact, this is a good feature because it keeps the wheels straight. You need to force it a little to start steering.

I think both solutions are good, @gyenesvi must be smoother while steering, "mine" might be a bit more stable. It is also a bit difficult to build because of those completely loose ... I bet LEGO would not approve it!

I can build both solutions and compare them but only next weekend as I don't have all the parts with me right now.

[stevendejong]

2 hours ago, vascolp said:

I can build both solutions and compare them but only next weekend as I don't have all the parts with me right now.

Great. This puzzle has been fun to solve together.

 

3 hours ago, gyenesvi said:

What I'd do is I'd order all the pieces required for these two final alternatives

I will do that, adapting the bus now so we have an actual demo vehicle to test. Stay tuned. ;)

[pow]

Another approach with ackermann (untested mock up)

It builds up pretty high

It needs some explanation:
I have wanted to introduce this modification of the virtual pivot steering to you for quite a while. Now I think it fits, because the topic is being discussed again and my version brings some useful improvements. So I quickly clicked together a 4 stud wide version.
One improvement is the "Ackermann mimicry", which is easily realized by moving the front pivot pin further forward.
The other is the possibility of a knob control. In the example picture this is indicated by the long black axle with white angled liftarm, which pushes on the extended steering arm (light blue 5 lift arm) via a the orange liftarm. The long lever results in a very smooth steering behavior that is easy to control.

studio-File: https://bricksafe.com/files/wop/studdstuff/4-wide-virtualpivot-steering-with-ackermann-prototype.io

Edited July 5, 2023 by pow
added explanation

[stevendejong]

On 7/5/2023 at 3:47 AM, pow said:

Another approach with ackermann (untested mock up)

Wow, this looks impressive. It does require a lot of room within a 6-stud vehicle tough, and I think the white 90 degree liftarm would need more space than the 4 studs inside a 6-stud vehicle? Would love to see how it turns.

[pleegwat]

3 hours ago, stevendejong said:

I think the white 90 degree liftarm would need more space than the 4 studs inside a 6-stud vehicle?

when turned 45° clockwise, it would extend out 3.51 studs (2.5 × √2) to the side of the center of the vertical axle.

[pow]

3 hours ago, stevendejong said:

the white 90 degree liftarm would need more space than the 4 studs

That is possible. This mock up is meant to show the principle. i've tested it in a much wider (9 studs) build. @stevendejong What could be interesting for you is the steering knob.

29 minutes ago, pleegwat said:

it would extend out 3.51

thanks for the calculation  In my larger build i used the L-shaped 4x2 Liftarm. 

This image is just a quick mock up, as i wrote.

[vascolp]

So I build both. Pictures below.

One pivot axle solution has a bigger steering radius. And when you force it to turn more, the   part tends to come out slightly. But requires less embracing and it is easier to build.

The Barrel is fine but it is not perfect because it is very angular and sometimes it collides with the tan pins that connect to the wheel holders. The pulley (two pulleys) solves this because its rounded.

[stevendejong]

On 7/10/2023 at 12:21 AM, vascolp said:

So I build both. Pictures below.

One pivot axle solution has a bigger steering radius. And when you force it to turn more, the   part tends to come out slightly. But requires less embracing and it is easier to build.

The Barrel is fine but it is not perfect because it is very angular and sometimes it collides with the tan pins that connect to the wheel holders. The pulley (two pulleys) solves this because its rounded.

HOW DID I MISS THIS POST? Geez, wow. I really don't understand why I wasn't notified of your amazing reply.

So you would prefer the single axle pivot and not a barrel but a double pulley?

[vascolp]

Maybe my mistake, I didn't refer you ...

I am a bit suspect, but preffer the two axle solution with pulleys .

The barrel is "so tall" that sometimes it gets stucked against the axle-pin connectors.

The single axle solution steers a bit less and it is a bit loose in the center. The two axle solution, as it bends the axles a bit, has a good rest centered position and at maximum steering (check first picture).

But they are very similar....

I have already unbuilt this.

[stevendejong]

18 hours ago, vascolp said:

Maybe my mistake, I didn't refer you ...

I am a bit suspect, but preffer the two axle solution with pulleys .

The barrel is "so tall" that sometimes it gets stucked against the axle-pin connectors.

The single axle solution steers a bit less and it is a bit loose in the center. The two axle solution, as it bends the axles a bit, has a good rest centered position and at maximum steering (check first picture).

But they are very similar....

I have already unbuilt this.

Understood. So, the two axle but with pulley wheels. My part shipment got lost by GLS, which is why I haven't built it yet. :)

[stevendejong]

Hi all! I finished a bus with the mechanism we developed here. Instructions (free) are here.

For people that just need the instructions for the steering mechanism, look here.

 

[gyenesvi]

On 9/8/2023 at 8:11 PM, stevendejong said:

Hi all! I finished a bus with the mechanism we developed here. Instructions (free) are here.

The end result is so cute :) Great to have a steered axle at such a small scale, I would have appreciated that a lot when I was a kid and played with this kind of lego!

[stevendejong]

23 hours ago, gyenesvi said:

The end result is so cute :) Great to have a steered axle at such a small scale, I would have appreciated that a lot when I was a kid and played with this kind of lego!

Thanks! What you are saying made me realize why I am not selling too many of my MOCs... I design toys. AFOLs prefer something more... EPIC... than a cute little bus. :)