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Steering mechanism for tight wheel wells?


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#1 Superkalle

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Posted 15 June 2011 - 12:49 PM

I've been playing around with this idea to design a simple steering mechanism that would allow wheels turning in tight wheel wells. On official LEGO models, the wheels turning point is almost never inside the center of the wheel, so the entire wheel moves forward and backward during turning, thus needing much wheel well space.

See attached video to see what I want to accomplish. Now the million dollar question: Have any of you seen or designed such a mechanism (no need to re-invent the wheel :classic:). And if not, any ideas how I would do it? I'm intending to have it in a 8 stud wide vehicles, so its going to be tight.

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#2 Sokratesz

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Posted 15 June 2011 - 01:30 PM

Sounds like a nice challenge, I'll see if I can create something this weekend..

Any other limitations? 8 studs wide incl wheels?

#3 roamingstudio

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Posted 15 June 2011 - 01:39 PM

View PostSokratesz, on 15 June 2011 - 01:30 PM, said:

Sounds like a nice challenge, I'll see if I can create something this weekend..

Any other limitations? 8 studs wide incl wheels?
What about wheel size and height restrictions?
The problem with wheel rotation is that the rotation axis is not aligned with the wheel... if you made a L shape lever arm you could place the rotation point over the wheel - but of course it would obstruct the nice Lego wheel trims...

I could see a use of the eccentric technic CAM's 6575 Posted Image laid flat across the top of the wheel to provide a different rotation point.

Edited by roamingstudio, 15 June 2011 - 01:40 PM.


#4 Sokratesz

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Posted 15 June 2011 - 01:47 PM

I was thinking something along those lines but it may quickly get too large vertically. A central axle with pivoting wheel mountings sounds better to me.

- Sok.

#5 DLuders

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Posted 15 June 2011 - 01:52 PM

One could consider the design of the 8207 Dune Duster/ Hawaiian Beach Racer set, and modify it to make it more narrow.  Some of the steering parts used in that set could be used in an 8-studs-wide Lego car having tight wheel wells.  Specifically, the 4261 "Technic Steering Arm" is key; the pivot point is centered on the wheel.

Posted Image  

In the 8207 Building Instruction picture below, the black 8L 2792 "Technic, Steering Rack Top" needs to be replaced with a shorter Technic Plate, such as the yellow 4263 "Technic, Plate 1 x 4 with Toothed Ends" or the yellow 2711 "Technic, Plate 1 x 5 with Toothed Ends, 2 Studs and Center Axle Hole".  The "arm" part of the 4261 "Technic Steering Arm" is moved laterally by a 8z (8-toothed) Technic Gear rolling along a grey Technic Rack mounted on a thin Technic Plate.  This is illustrated in the colorful picture below from Blakbird's Technicopedia.  Replace the blue Plate with a Technic Plate, that allows for a 3749 "Technic, Axle Pin without Friction Ridges Lengthwise" to connect into the 4261 "Technic Steering Arm".

Posted Image Posted Image Posted Image Posted Image  Posted Image   Posted Image
Posted Image

Edited by DLuders, 15 June 2011 - 02:18 PM.


#6 roamingstudio

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Posted 15 June 2011 - 02:13 PM

View PostSokratesz, on 15 June 2011 - 01:47 PM, said:

I was thinking something along those lines but it may quickly get too large vertically. A central axle with pivoting wheel mountings sounds better to me.

- Sok.
I know what you mean... but designing an eccentric turning mechanism (so both wheels work without 'scuffing' when the model turns) is not going to be easy with existing parts.

Superkalle - is this so that you can make scale minifig models in 8 wide? I know the 'model team' steering is too large, but it might be the only way... For small radius you might be better off having 'fixed wheels' with the whole assembly (including wheel arches) pivoting in a subtle way underneath the body of the vehicle (and not the in simple cart mechanism).

Could you use some of these to offset the wheel pivot point? 88072 Posted Image
Coupled onto some of these... Posted Image, perhaps with some of these Posted Image

Edited by roamingstudio, 15 June 2011 - 02:14 PM.


#7 Bartholomew

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Posted 15 June 2011 - 02:17 PM

Rubber bands could do the trick.

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Edited by Bartholomew, 15 June 2011 - 02:18 PM.


#8 roamingstudio

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Posted 15 June 2011 - 02:40 PM

View PostBartholomew, on 15 June 2011 - 02:17 PM, said:

Rubber bands could do the trick.
Actually... I was thinking that putting the rotation point here might help... but it would need to be at an odd stud width.
post-4755-130813869737.jpg
Of course it would not be ideal for some turning circles, but would make the visual effect work (if functionally it is not ideal).

Edited by roamingstudio, 15 June 2011 - 02:40 PM.


#9 le60head

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Posted 15 June 2011 - 03:14 PM

That's an ambitious project. I like it !
I haven't tried to fit a steering wheel in such a tight wheel well yet.

I am guessing two things might help:
1 - move the pivoting point as close as possible to the center of the wheel.
2 - use narrower wheels

I have a suggestion for a steering mechanism that might work. I haven't tested it out yet, so i would say it's experimental.
I've attached a screenshot. I can send you the .ldd file if u want.

Hope i helped :)

P.S.
For some reason, there's a limitation to attachments to ... 17 kb?!?
Sorry for the crappy image :)

#10 Sokratesz

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Posted 15 June 2011 - 03:35 PM

That might work if you were somehow able to get the other holding bar for the wheel mount to slide in the opposite direction.

#11 le60head

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Posted 15 June 2011 - 03:47 PM

it's hard of me to explain with words how this steering mechanism is supposed to work.

The mounting point ( the axle where the cog wheel is ) should be connected to the steering motor.

When the axle turns, it pushes one holding bar in one direction ( inside) and the other holding bar in the opposite direction).

Thus the wheels themselves are turned, and their turning point is over the center of the black connector, where the bley peg is inserted.

Hope what i just explained is understandable.

In principle, it works just like an ordinary rack and pinion steering mechanism.

#12 Ultimario

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Posted 15 June 2011 - 04:26 PM

I saw something useful that one of the members in my countries forum had made. Not exaclty in your size but might give some ideas.

http://www.flickr.co...in/photostream/
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#13 Nazgarot

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Posted 15 June 2011 - 06:15 PM

Hi,

I've just mocked up something in LDD.

I'm not at home, so I haven't tested this, but i believe it should work do to the tolerances Lego operates with. It's a bit more compact than what you drew, it hasn't really got a good turning radius, and you will have to find a way to fit it to the car, but i gives the desired effect...







Hope this helps. If not, I have several more ideas, this was just the most promising. :)

-ED-
We are traveling through time, forward... That is an amazing prospect.

#14 mahjqa

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Posted 15 June 2011 - 06:28 PM

Posted Image

#15 garson

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Posted 15 June 2011 - 10:13 PM

http://farm6.static....f4baf6330_z.jpg

would this fit?

#16 Superkalle

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Posted 16 June 2011 - 12:10 AM

A lot of good ideas. Thanks a lot guys! I'll go ahead a and try some of these out.

I wonder why not TLG uses any of these methods, instead of creating such ugly, oversized wheel wells, such as this one:
http://www.brickset....ail/?Set=4896-1
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#17 Nazgarot

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Posted 16 June 2011 - 07:47 AM

View PostSuperkalle, on 16 June 2011 - 12:10 AM, said:

A lot of good ideas. Thanks a lot guys! I'll go ahead a and try some of these out.

I wonder why not TLG uses any of these methods, instead of creating such ugly, oversized wheel wells, such as this one:
http://www.brickset....ail/?Set=4896-1


Yes, i wonder the sme. I was disapointed when the new technic 8110 U400 unimog was precented. Here they have made new hub parts, but the rotation point is 5! studs away from the hub... I want a part that puts the rotation point inside the rim, and wheels with enough offsett that the rotation point is in the center of the wheel.

I'm usually not a fan of modifying lego parts, but now I grow tired of waiting for these kinds of parts, so I might make some by myself...
We are traveling through time, forward... That is an amazing prospect.

#18 AussieJimbo

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Posted 16 June 2011 - 07:59 AM

I'd like to see a compact steering solution that's compatible with the Faller Car System, as seen at Minatur Wunderland.



It would be awesome to add moving vehicles to a Lego city.

:classic: :classic:

#19 legolijntje

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Posted 16 June 2011 - 12:48 PM

Maybe you can use THIS piece whit  THIS piece.

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#20 Sokratesz

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Posted 16 June 2011 - 01:27 PM

View Postlegolijntje, on 16 June 2011 - 12:48 PM, said:

Maybe you can use THIS piece whit  THIS piece.

That would make it at least 6 studs wide excluding the wheels, and depending on the wheel will put the rotation axis outside the center by quite a bit.

- Sok.

#21 le60head

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Posted 16 June 2011 - 02:07 PM

View PostAussieJimbo, on 16 June 2011 - 07:59 AM, said:

I'd like to see a compact steering solution that's compatible with the Faller Car System, as seen at Minatur Wunderland.



It would be awesome to add moving vehicles to a Lego city.

:classic: :classic:

I totally agree with you!
I am still working on a model of a vehicle in minifig scale. I'm doing the finishing touches, and will present it very soon.
The steering mechanism i showed earlier in this topic was one of the ideas i had to make it steer. I've used a different approach though.

#22 Superkalle

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Posted 21 June 2011 - 10:12 PM

View Postle60head, on 16 June 2011 - 02:07 PM, said:

I am still working on a model of a vehicle in minifig scale. I'm doing the finishing touches, and will present it very soon.
The steering mechanism i showed earlier in this topic was one of the ideas i had to make it steer. I've used a different approach though.
Looking forward to seeing that!
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#23 Superkalle

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Posted 21 June 2011 - 10:59 PM

View Postmahjqa, on 15 June 2011 - 06:28 PM, said:

Posted Image
Unfortunately, this doesn work since the parallogram created is not "perfect". When the steering angle goes beyond about 20 degrees, it puts stress on the whole design. It might not be noticable they way you did it, but if you attach the two vertical studs on system plates using 2460, then it won't work.

Now, on to the next concept idea to test  :classic:
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#24 Brickend

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Posted 22 June 2011 - 12:24 AM

Parallelogram is good, only the perpendicular connectors anchor to a part that starts three studs wide and decreases in the turn. The distance between the perpendicular connectors is fixed, hence the self destruction. It's harder to describe than to make work.

#25 Superkalle

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Posted 22 June 2011 - 11:02 AM

View PostBrickend, on 22 June 2011 - 12:24 AM, said:

Parallelogram is good, only the perpendicular connectors anchor to a part that starts three studs wide and decreases in the turn. The distance between the perpendicular connectors is fixed, hence the self destruction. It's harder to describe than to make work.
Yupp, I understand fully.

Question remain now: Is there a solution around this.
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