Steering mechanism for tight wheel wells?

[msk6003]

3 hours ago, SaperPL said:

Which tyres are those btw?

61254 23x7 tire with 13971/56902(Both pin hole) or 56903(Axle hole) wheel.

[vascolp]

12 hours ago, stevendejong said:

Thanks for the feedback and suggestion. I don't think I understand how to attach the steering axle if I use two sliding axles. Also, the parallellogram needs to rotate with respect to the sliding axle.

Would you be able to provide a screenshot / render?

Gears instead of tires and blue pins instead of tan ones but you'll get it. 

These  parts are there to keep things in place. Probably better with some of these:

More images here: https://bricksafe.com/pages/vascolp/varios/stering-for-6l-car

 

 

[stevendejong]

16 hours ago, vascolp said:

Gears instead of tires and blue pins instead of tan ones but you'll get it. 

Wow, thanks for doing this. Definitely an interesting idea and not falling apart!

What I find problematic is that the axles are under considerable stress. We're basically bending LEGO.

[stevendejong]

OK, went back to the drawing board with the 5W idea and achieved this with (almost) the same material:

Advantages:

• The construction is sturdier.
• The wheels don't rotate exactly around their own axis, but it's quite close.
• We can get 20 degrees of rotation within a four stud gap.

Disadvantage: the mechanism requires five studs, so for a six-stud vehicle, we need to use thin rims and tires.

Edited July 1, 2023 by stevendejong

[vascolp]

On 7/1/2023 at 4:28 PM, stevendejong said:

Wow, thanks for doing this. Definitely an interesting idea and not falling apart!

Don't quit 4-wide yet! 

 

[stevendejong]

3 hours ago, vascolp said:

Don't quit 4-wide yet! 

So, you think the stress on the axles isn't that much of a problem? Then maybe we found a solution... One challenge left, which is that the connector to the steering axle on top requires another stud of additional height. I'm thinking about this and will come back here.

[vascolp]

9 hours ago, stevendejong said:

So, you think the stress on the axles isn't that much of a problem? Then maybe we found a solution... One challenge left, which is that the connector to the steering axle on top requires another stud of additional height. I'm thinking about this and will come back here.

No stress problems., The axles will bend sligthly but it seems aceptable to me.

For the steering you can use one of this ,so a bit thinner... 

For a bus the height should not be that much of a problem, I suppose... If it was a car,... that would be different.

[stevendejong]

33 minutes ago, vascolp said:

For a bus the height should not be that much of a problem, I suppose... If it was a car,... that would be different.

True, but I can achieve a lower height with the original (entirely non-stressed) mechanism and 41678 (as suggested above).

Double axis to the left, single axis to the right:

I really like the double axis design, because it does not have spurious pin holes / ball socket, like mine does. Also, the parallellogram deforms around its center and not an edge. But we need to find a way to make it less high. :)

 

[vascolp]

I tried, you can use these  instead of these   and then one of these  fits inside. The problem is how to rotate this 3L beam with an axle...

 

[stevendejong]

1 minute ago, vascolp said:

I tried, you can use these  instead of these   and then one of these  fits inside. The problem is how to rotate this 3L beam with an axle... 

 

How about we use 43093 (axle 1L with pin with friction ridges)?

[stevendejong]

Okay, we've found a solution that is sturdy, efficient and compact. Renders below.

Can I post it on my Rebrickable, @vascolp? I would also like to open up a new topic on the Technic forum so the build may be more discoverable. I will of course give you credit for your contribution! Send me a link to your website / profile / MOC store and a watermarked version of the demo video, if you like.

Btw, I have rendered the mechanism to have a half stud gap between the mechanism itself and the sliding axle ends, because that allows putting everything in a System car without using jumpers.

 

[Edit] Replace the yellow liftarm with the pulley wheel 4185 to have an actual axle hole and to be able to fix the wheel to the red parts with a 1/2 bush.

 

Edited July 3, 2023 by stevendejong

[vascolp]

By all means, post wherever you want! 

I have a rebrickable entry too...

[gyenesvi]

Nice developments of miniaturization over here :) I wonder if it would be possible / advantageous to go back to single point pivots with the below a construction? It's not a single piece in the middle, as in case of the double pivot version, but it seem solid enough. Also, the other question is if there's enough space for it.

What do you think @stevendejong?

[stevendejong]

6 hours ago, gyenesvi said:

go back to single point pivots with the below a construction

Brilliant out of the box thought. Steering angles and wheel position are the same. As far as I can oversee, the advantage is that there is no stress on the pivots, so we can comfortably rotate all the way. With the double axle, there is a little bit of stress / bending. A disadvantage is that the mechanism is connected to the rest of the car in fewer places (3 instead of 5, 1 of which is the steering axle). Another disadvantage may be that the mechanism is slightly wider (but also, it still fits within a 4 x 4 stud space).

I think the only way to find out how the double and single axle build compare is by building them. @vascolp or @gyenesvi, do you happen to have the pieces lying around? I've been building mostly with System bricks (which I had as a child and my 6yo currently prefers over Technic).

This has been great so far.

 

Edited July 3, 2023 by stevendejong
I understood :)

[gyenesvi]

7 minutes ago, stevendejong said:

Can you make a render without the 4185, LBG axle and bushes? I am trying to understand what's below them and how this works and how we could mount it in a vehicle. :)

It's exactly the same as the versions above with the double pivot, only this part is replaced with a construction with 2L thin liftarms in LBG and the DBG axle-pinhole-axle connector. Does this make it clear?

[vascolp]

stevendejong , I think the half stud gap is not so good in your render because it allows the whole thing to slide horizontally...

Gyenesvi solution is interesting because one can have an axle from one side to the other and also the pivot axles can be replaced by a pin (with friction, that's all there is...) which keeps things together vertically wise. Furthermore, it might allow to make it less high. But it requires half stud gaps horizontally to alow the rotation...  so the whole thing will woblbe along the axles too... It also can rotate along the horizonal axle since it is only one axle...

 

[stevendejong]

For completeness / overview here are the two versions.

30 minutes ago, gyenesvi said:

Does this make it clear?

Yes sorry meanwhile I figured it out.

@vascolp, concerning the sliding / wobbling / rotation around the sliding axles, I think this may be remedied by the steering axle on top, you'd probably stick that axle through a ground plate (at least) of the vehicle on top of it? I guess we should test it, but as I said above I don't have the parts. :)

Does your version not get a little jammed if you remove the half stud gap between the mechanism and the 1x2 brick with two pin holes? In Studio, I'm seeing some overlap between parts. If there is no jamming, I think adding bushes to the base of the black axles would work best, so we end up with the wheels neatly in the middle of an 8 stud construction. Otherwise, the 1x2 brick would end up on a jumper. Same for @gyenesvi's idea by the way.

Edited July 3, 2023 by stevendejong

[gyenesvi]

But now with the single pivot version, one of the two pivots can be fixed (to a technic plate for example), as it was in the original design, so that would not allow it to slide back and forth, neither rotate horizontally. Is that what you meant @vascolp?

Also, maybe using this piece  instead of the pulley would be more solid than fiddling with the half bushes? It does not need to be held there vertically, vertical positioning will be taken care of by the pivots.

[vascolp]

It does not get jammed. But it is also 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 there must be something on top of the vertical axles, otherwise wheels will go up. And relying in the pulley (or the other part, the Weapon Barrel) to keep things in place does not seem strong enough. That’s why I embraced with vertical 3L thin liftarms and used horizontal 4L thin liftarms connected by the 5L axles in my video (black and yellow). Yet steering command is not good enough, it is a bit too high. I wish we had a 3L liftarm with an axle connector in the middle, because it would fit very well in the middle of those 5L grey axles…

[stevendejong]

8 hours ago, vascolp said:

I think there must be something on top of the vertical axles, otherwise wheels will go up.

I think the chassis of the car/bus will be directly above it, so there's no room for it to go up?

8 hours ago, vascolp said:

I embraced with vertical 3L thin liftarms and used horizontal 4L thin liftarms connected by the 5L axles

That does have the side effect of (far) exceeding the 6-stud target size though.

8 hours ago, gyenesvi said:

one of the two pivots can be fixed (to a technic plate for example)

Yes, this would also mean you would put the steering axle above that pivot and not in the middle, because the middle will move a little.

I guess the only thing we can do to find out what's best is physically build these designs and test them.

[gyenesvi]

8 hours ago, vascolp said:

I think there must be something on top of the vertical axles, otherwise wheels will go up. And relying in the pulley (or the other part, the Weapon Barrel) to keep things in place does not seem strong enough. That’s why I embraced with vertical 3L thin liftarms and used horizontal 4L thin liftarms connected by the 5L axles in my video (black and yellow). Yet steering command is not good enough, it is a bit too high. I wish we had a 3L liftarm with an axle connector in the middle, because it would fit very well in the middle of those 5L grey axles…

Oh, I see what you mean now. But I think the barrel piece can have the same role. My idea was that it would be covered by a technic plate from the top to route the axle and build the floor of the bus anyway, so that would hold it in place from the top, and the pivot points would be held from the bottom, that should be enough I guess. Also, the barrel has a pretty flat surface (unlike the pulley), and it could give good stability and smooth movement.

2 minutes ago, stevendejong said:

I guess the only thing we can do to find out what's best is physically build these designs and test them.

Agreed, I think it's time to experiment physically instead of overthinking :)

Edited July 4, 2023 by gyenesvi

[stevendejong]

25 minutes ago, gyenesvi said:

Oh, I see what you mean now. But I think the barrel piece can have the same role. My idea was that it would be covered by a technic plate from the top to route the axle and build the floor of the bus anyway, so that would hold it in place from the top, and the pivot points would be held from the bottom, that should be enough I guess. Also, the barrel has a pretty flat surface (unlike the pulley), and it could give good stability and smooth movement.

That's what I thought too.

25 minutes ago, gyenesvi said:

I think it's time to experiment physically instead of overthinking :)

So, do you guys have the bricks to do so? I could order a batch of Technic as well, but currently don't have much Technic except my early 1990s stuff. :)

[gyenesvi]

29 minutes ago, stevendejong said:

So, do you guys have the bricks to do so? I could order a batch of Technic as well, but currently don't have much Technic except my early 1990s stuff. :)

I guess sooner or later you'll have to order it if you want to build that bus anyway :) Plus all the constraints only come out once you have the proper body around it. I'd be lacking system parts anyway..

[vascolp]

I got some 1x2 bricks from a MOC around, so here it is another version. I have no barrel with me but two pulleys do the job. I also don´t have a 2x8 technic plate so ... imagine there is an axle through the non technic grey one!

It should work!

 

[gyenesvi]

Ooops, I noticed a problem with my single pivot design.. If one of the pivots is fixed, and the center point moves (say, backwards), then the upward going axle would also move (backwards), but that cannot happen if it's held in place by a technic plate.. So it really needs the pivot points sliding on both ends, and then maybe the double pivot makes for a more stable build (just as @vascolp did right now), but the single-pivot can still be used. Here's my updated design, I have changed the sliding-axle part to have an axle-pin connection instead of the axle in the pinhole, though it has the disadvantage that the excess of the sliding axle protrudes out of the 8 module long assembly, not into the inside, as in the build of @vascolp. His design is a bit more compact and solid enough I think (especially with a barrel piece).

I could actually test this later though..