Landracing Forum
Tech Information => Steering - Suspension - Rear End => Topic started by: Fred on November 24, 2009, 07:20:27 PM
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I see some streamliners and motorcycles use of fixed axle steering through the wheel hub, I assume there is a bearing and pin assembly in it? Is there any information on this type of design out there or even a company or person who makes it for sale?
Thanks - Fred :?
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fred you might ask kent 1212fgbs he told me that he had plans for a hub center steer willie buchta
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Hi Willie,
Thanks for the reply, since I am new at this chat stuff would you mind suggesting how to contact Kent 1212fgbs?
Fred
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Try this website to reach Kent:
http://www.motobody.com
FREUD
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We had a "focusing link" on the Breedlove/Fossett car. By adjusting the mounting points of the linkage, fully adjustable roll and trail were possible. Contact me for a link to the designer of the last itteration.
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We designed and built our own system and it works quite well.
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We had a "focusing link" on the Breedlove/Fossett car. By adjusting the mounting points of the linkage, fully adjustable roll and trail were possible. Contact me for a link to the designer of the last itteration.
http://www.rotaryeng.net/roadable.html
A very good explanation of the focusing link and how it works. For a dual tire front axle, the vertical links need to be angled to focus at the ground or above it. The side links point at the pivot point, and the distance between this “focal point” and the tire contact patch is the effective trail.
The real question is whether the links could be attached to a frame for two wheels in-line. Would effective trail be measured against the center between the two contact patches?
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I don't see why it couldn't be used on a 2 wheeled machine. It can be set up to achieve the same steering motion that the front wheel on a motorcycle sees. Seems to me that effective trail would be measured by locking the frame down rigid and swinging the steering through it's motion. The radius of the contact patch arc is the trail. Figuring out effective rake may be a trick, but it seems that rake in and of itself is not the most important issue as far as stability is concerned, as least if you believe Tony Foale. http://www.tonyfoale.com/
http://www.rotaryeng.net/roadable.html
A very good explanation of the focusing link and how it works. For a dual tire front axle, the vertical links need to be angled to focus at the ground or above it. The side links point at the pivot point, and the distance between this “focal point” and the tire contact patch is the effective trail.
The real question is whether the links could be attached to a frame for two wheels in-line. Would effective trail be measured against the center between the two contact patches?
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We have been making/building Hub-Centres for both solo M/C's and sidecars for many years............
You have to fully understand what it is all about..........and make it fully adjustable for the various
surface and track and/or street conditions..........if done properly it is the "only way to go" in both sollo's and sidecars..............
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We have been making/building Hub-Centres for both solo M/C's and sidecars for many years............
You have to fully understand what it is all about..........and make it fully adjustable for the various
surface and track and/or street conditions..........if done properly it is the "only way to go" in both sollo's and sidecars..............
I've seen hub center setups at a distance for years, but never got close enough to one to understand how they work. I've always thought they were very clever, and wondered about the forces on the hub (small focal point, high moment) vs. the focusing link (wide spaced pivot points, low moments). Are there pictures, and how is trail (caster) created with the hub at the center; how is bump steer avoided in single-side systems, how do we deal with stiction in the center hub, etc.?
One big disadvantage/advantage of the focusing link is that high steering angles compress the suspension. This adds "virtual trail" sprung and damped by the suspension (usually coil-over-shocks). Great for LSR, not so great for a road racer or in the pits.
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Eric from the diagram i cant figure how the focusing link works could you show a better diagram---i hope im not the only one , if i am please dont tell anyone thanks ============willie buchta
http://www.google.com/search?hl=en&source=hp&q=hub+center+steering&aq=0&oq=hub+center+steer&aqi=g1g-m2
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That makes two of us Willie. :-(
Pete
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Eric from the diagram i cant figure how the focusing link works could you show a better diagram---i hope im not the only one , if i am please dont tell anyone thanks ============willie buchta
It's not completely intuitive, the guys who made the one for Sonic Arrow missed the fact that they set it up to be unstable in both trail and roll.
Look at it in plan view (from the top) and trace the angle of the side tie rods. As we push the back of the swing arm left or right, the whole assembly rotates around a virtual pivot point that is where the two arms are pointing in space. The arms should be set up so they point forward of the tire contact patch, the distance between that point and the contact patch is the amount of trail. This should be at least 4" and 5% of wheelbase on vehicles longer than 100" for LSR.
Looking at it from the front, the vertical arms control the amount of roll. If the arms are vertical, the tire will roll like a motorcycle fork. For flat tires on 3 wheel vehicles, this is unstable. Inclining the vertical arms to form a "V" with the focal point at ground level creates zero roll and a slight proverse roll at high steering angles.
Done correctly, there is little load on the arms and lots of load on the shocks.
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Center hub
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Fred
i have a few different designs including one that Mike made for me and a couple Vesco center hubs.... Mike can make one for you as well as Fred Hayes who drew programs for the Vesco hubs.... i also have a Bimota hub that is kinda neat but pretty wimpy for 300mph.... I also have a king pin style that is on the Breese liner..... what are your plans?
Kent
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Center hub pivots on a short spindle inside the hub. Much like an I-beam axle only centered relative to the tire with a zero scrub radius. Caster remains the angle of the pivot with the vertical. If mounted in a single swingarm, caster angle changes as the suspension moves.
The focus-link arrangement is using two 4-bar linkage systems. One set controling pivoting in the vertical and one set for the horizontal. A four bar can approximate a pivot but on this, trail moves a bit with suspension travel and trail and camber have a unique pattern of movement with steering angle.
Thanks Blue.
I'm still trying to convince Solidworks to generate the ports in a head I want to test, so a long way from having motive power. If I get the power, you'll see a two wheeled streamliner with focus-link designed.
It's fun here, learn things. 8-)
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Thank you to everyone who posted on center hubs. Very interesting.
The focusing link has no bump steer at zero steering angle, and can have neutral, proverse, or adverse bump steering at high steering angles depending on the vertical and longitudinal spacing of the arm pivots on the swing arm. Bump-roll can also be changed the same way; it gets pretty complex. Locating everything at the back and minimizing the vertical and longitudinal distances between the pivots yields the most neutral setup.
Although it would be interesting to play with all of the permutations of bump-steer/bump-roll, experience with my hands on the bars/wheel tells me that it's best to go neutral.
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I have the plans and drawings i made my centersteering with. Go them from "Pappy" John Stege Mec. Engineer with the Gov. up in Portorchard Wa. can build or share the plans.
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If you are at "high steering angles" on a Bonneville car you are getting ready to do backwards!
Or you are in the pits.
Rex
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One big disadvantage/advantage of the focusing link is that high steering angles compress the suspension.
Vick
If you go to the tab and introduce yourself it would be helpful to all of us. Who are you, what is your background, are you a racer, what area do you live in.
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Vick's a spambot Glen.
Pete
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And "Vick" is gone. I banned the spambot this morning -- but I guess I missed a post or two. Sorry for the inconvenience, and thanks to the bunch of you that keep your eyes open and let me know when these Acuraholes get into the Forum.
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This is one way to avoid bump steer.
[/url]http://www.arrowracing.org/photogallery/photo12540/Center%20Hub%20Steering.JPG[url]
Gary
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woops that didnt work willie
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This is one way to avoid bump steer.
[/url]http://www.arrowracing.org/photogallery/photo12540/Center%20Hub%20Steering.JPG[url]
Gary
http://www.arrowracing.org/photogallery/photo12540/Center%20Hub%20Steering.JPG
Need a larger image..
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Top row of pics here: http://www.arrowracing.org/ (http://www.arrowracing.org/)
Mike
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http://www.arrowracing.org/images/Center%20Hub%20Steering.JPG
Thanks for the Info
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Does anybody have a photo of an actual focusing link steering setup? Or a more complete diagram? I'm kind of excited about the concept, but related information seems to be very rare on the internet, and the image on http://www.rotaryeng.net/roadable.html doesn't seem to provide a way to prevent the wheel from flipping upward. I imagine you'd add something like an additional link on each side, attached at the yoke above and horizontally in line with the side links, to vertically brace the side links.
I realize this post is ancient, but this subject really doesn't seem to be discussed anywhere else.
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The steering of the Buddfab 50cc LSR might qualify as focusing link, depending on the exact definition. And it's probably better for my purpose than the rotaryeng.net design. Sexy.
Images from:
http://www.buddfab.net/buildphotos.html
http://www.motorcycle-usa.com/287/1518/Motorcycle-Article/Salt-Addiction-Buddfab-Streamliner.aspx
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The roadable plane diagram does not show the springs and shocks that would prevent the U-shaped piece from flipping up, only the linkage. The buddfab also uses a 4-bar linkage to allow steering but is holding a leading-link fork. The arrangement of two 4-bar sets in two planes would be lighter, so a bit more suitable for flight.
Both work, as does center-hub steering. The nice bit is seeing the various solutions to a problem and being able to match how it couples the loads into the frame with the structure one selects (or already has). You also get to spend more time on other problems in the overall design because people shared. 8-)