designer
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| posted on 8/4/11 at 12:42 PM |
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Front suspension layout
Front suspension drawn.
Push rods to a single spring/shock, via a small, pivoting, frame mounted by pillow blocks on the chassis main beam. The frame will/should act as an
anti-roll bar, with the aim of a roll rate of zero.
[img]
 
front suspension layout
[/img]
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Miks15
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| posted on 8/4/11 at 01:00 PM |
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interesting,
have you got any up close drawings of the pivot section.
Cant quite get in my head how it works?
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speedstar
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| posted on 8/4/11 at 01:08 PM |
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Won't this cause one wheel to bounce up and down (off the road) when the other one is more loaded?
Id the suspension remains "independant" you surely need independant uprights?
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blakep82
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| posted on 8/4/11 at 01:16 PM |
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i don't think it will act as an anti roll bar. if you turn a corner, say to the right, the left wheel will 'lift', push on the
pivot, and allow the right wheel to drop. not even the shock absorber will give it any support. would only work well in a straight line where both
wheels are going up and down at the same time.
2 shocks is the only real way to do it i think
________________________
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don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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tomgregory2000
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| posted on 8/4/11 at 01:36 PM |
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One of the renault series of single seaters use this style of front suspension, cant remember which series but saw it my own eyes when i was at the
renault world series last year
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MikeCapon
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| posted on 8/4/11 at 01:36 PM |
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Monoshock front ends on single seaters are not unusual. Some of these run a second roll damper and anti roll bar but the principle is sound.
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hughpinder
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| posted on 8/4/11 at 01:47 PM |
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Staniforth had monoshock front suspension on the terrapin. It had beville washers for the roll resistance. I'll see if I can dig out a photo
from the book when I get home. In your design the roll resistance would be so large that the only roll will be the flex of the suspension and arms, so
if one wheel goes over a bump you'll just lift the other off the ground (I think).
Regards
Hugh
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Theshed
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| posted on 8/4/11 at 01:48 PM |
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Looks good. But you seem to have 2 bars on your pivot running across the car - a sort of square. Is it the flex in that which gives you your
"roll bar"? That will not be a pure twist will it? Whats wrong with the bellville washer set up that is usual in single seaters?
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designer
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| posted on 8/4/11 at 02:03 PM |
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Unlike a normal 4 wheeler, on a reverse trike, all the roll has to be controlled by the front wheels, and here, suspension movement will cause an
upward push on the pivoting frame, not a rolling pressure.
Well that's the theory!!
The bottom cross piece of the small frame is long and is mounted on aluminium pillow blocks (you can see the mounting holes in the drawing) which will
stop any lateral movement.
A bellville washers system will take me away from what I want; simplicity.
I will post a layout of the frame this evening.
[Edited on 8-4-11 by designer]
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MikeRJ
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| posted on 8/4/11 at 04:57 PM |
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Aiming for infinite roll resistance surely isn't a good idea? I don't think your design would actually achieve that in practice, as the
frame would twist/lozenge to some extent unless made very stiff/heavy. This would give you some unknown and non-adjustable roll stiffness, and
I'd have to wonder how long the (presumably) welded joints on the frame would last under that kind of punishment.
[Edited on 8/4/11 by MikeRJ]
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designer
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| posted on 8/4/11 at 06:39 PM |
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This is a more detailed picture of the suspension bridge.
The frame pivots on the wider, bottom tube, and the two uprights have ball joints to attach the push rods.
 
Suspension bridge
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Sam_68
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| posted on 10/4/11 at 08:04 AM |
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Designer,
As others have said, I'm not at all convinced it's a good idea to have zero roll compliance on a road car, even on a trike, but since
monoshocks are new for road use, who am I to say?
IIRC, they were first established by Dallara in F3 and everyone said they'd be fine for smooth circuits but hopeless on relatively bumpy,
cambered hillclimb venues, yet they are now quite commonplace on the hills too. Every one I have seen has got some roll compliance built in,
though.
As MikeRJ says, however, if you stick with your current zero-roll compliance approach, your 'bridge' design could do with being
triangulated: at the moment you're putting bending loads into the middle of tubes and the roll forces will try to turn the main
'square' of tubes into a parallelogram. Triangulation would be a better, more elegant solution than the corner fillets you're
showing at present.
I'm working on a monoshock arrangement for a road legal single seater myself, though I'm not ready to go public yet. U2U me if
you're interested in comparing notes, and if we can convince you to build in some roll compliance, I have some drawings by a professional
(ex-F1) designer for a couple of monoshock rocker arrangements using the usual belville washers that might interest you.
As an aside, one of the interesting things with monoshocks is that where you do build in roll compliance using belvilles or similar, it works
completely differently to a conventional anti-roll bar: on a normal ARB, a bump at one wheel tries to lift the other wheel, whereas with the monoshock
arrangement it tries to force the opposite wheel down harder against the tarmac.
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Uphill Racer
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| posted on 31/5/11 at 12:40 AM |
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quote:
Originally posted by hughpinder
Staniforth had monoshock front suspension on the terrapin. It had beville washers for the roll resistance. I'll see if I can dig out a photo
from the book when I get home. In your design the roll resistance would be so large that the only roll will be the flex of the suspension and arms, so
if one wheel goes over a bump you'll just lift the other off the ground (I think).
Regards
Hugh
Stanny never had monoshock suspension on his Megapin. Twin inboard spring and damper units via pushrods operating a conventional anti roll bar via
pullrods.
Personally I'm not a fan of monoshock systems for anything else than fast flat applications.
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scootz
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| posted on 12/8/11 at 06:57 PM |
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How's this coming on Designer? Any progress?
I was looking at the Formula BMW...
[Edited on 12/8/11 by scootz]
It's Evolution Baby!
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designer
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| posted on 12/8/11 at 07:34 PM |
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I did another layout which could either use springs or belville washers:
http://www.locostbuilders.co.uk/forum/31/viewthread.php?tid=153779
But I think I am going to stick with the original version.
Been a bit lax lately as I have been to-and-froing between here, England and Germany, but I will be back on the drawing board late September.
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