Sliding pillar suspension on trike ? possible

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Hi all

Could this work on a recumbent trike ?



So the sliding part is 2 precision i/d tubes welded to a piece of rectangular tubing with a axle hole in it that slides on the unthreaded portion of a M12 bolt.
At the bottom are a pair of thick rubber washers and above 2 or 4 car valve springs to provide the suspension.
It is attached by a pair of right angled aluminum plates to a flat surface i.e plywood sides of a delta velomobile.

If it could be made to work it has several [ percived [ by me ]] advantages over a standard Mcpherson suspension as it does not need a strong top mounting , and is neatly completely inside the wheel arch.

I suspect it will be hard to weld the parts with enough precision and will need to be shrouded from road dirt ?

Paul
 
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I suspect the side-loading would cause it to jam all the time. :(
 
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The side loading is likely to tear at the plywood too with 10" of leverage at the road interface but spreader plates front and back would help with sufficiently thick ply. The spreader plates would be getting on for a full chassis weight though which was what I was finding when trying things on the drypod2. Easier to build a chassis and then keep wood weight to a minimum imho.

As an alternative idea what about 150kg trailer suspension units? They fit under the axle and take up almost no room inside an arch. If it's a bit too stiff then extend the arms but with rider, trike and cargo they'd be in the right ball park to start with. They work by an inner shaped arm twisting against high strength rubber. I'm actually now wondering why I haven't seen them in use on a trike already. The only negative I can think of now is any welding to modify them for a bike wheel would need to be done slowly to keep the heat from melting the rubber. Perfectly doable though.
 
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I suspect the side-loading would cause it to jam all the time. :(
My original idea was to use 4 x M12 rod end bearings which would give some adjust-ability but more weight.

Maybe it will be to compact and so hard to mount , certainly onto wood without causing problems.

Paul
 
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The side loading is likely to tear at the plywood too with 10" of leverage at the road interface but spreader plates front and back would help with sufficiently thick ply. The spreader plates would be getting on for a full chassis weight though which was what I was finding when trying things on the drypod2. Easier to build a chassis and then keep wood weight to a minimum imho.
Probably , still dreaming of a plywood monocoque despite it's obvious problems of strength and weight.

As an alternative idea what about 150kg trailer suspension units? They fit under the axle and take up almost no room inside an arch. If it's a bit too stiff then extend the arms but with rider, trike and cargo they'd be in the right ball park to start with. They work by an inner shaped arm twisting against high strength rubber. I'm actually now wondering why I haven't seen them in use on a trike already. The only negative I can think of now is any welding to modify them for a bike wheel would need to be done slowly to keep the heat from melting the rubber. Perfectly doable though.


Wow I though 150kg is he mad ?
however some scribbles on the back of a menu suggests they are spot on ! weight wise a sobering thought .

I suspect they are to heavy for our intended use ?

The arms looks as they could be solid ?
If so the the arm could be chopped off [ to get rid of the heavy stub axle ] right at the pivot and a lighter rectangle tube welded in it's place.

They are 4.6 kg so that's a target to get below for some diy units ?

Paul
 
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To weld at that end of the arm you'd probably need to disassemble them to avoid melting the rubber. I believe they are pressed in with a big hydraulic press though. Weight wise you'd save the weight of two trailing arms for a more regular set up but as you say still heavier.
 
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It's worth saying that the bulk of those units' weight will be in the solid stub axles that'd be cut off to make way for a small piece of tube for a bike axle mount. I suspect you'd loose at least a kilo there.
 
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Popshot

Look like welds to me ?



Paul
 
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These are just beefed up chain tensioners with rubber " torsion bars". Easy to make yourself.

"Big box section" as frame. Small box section as "torsion bar",
The room in between filled with 4 pieces of "fitting" Oring
 
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Welded - yes. Those stub axles are solid and therefore weighty though. If the stub axle is cut off flush or somewhere close to flush with the arm then a drill could be put through what's left to make the wheel mounting hole.

Probably not as easy as you'd wish them to be to make. They are pressed together so hard as to make side to side motion negligible. It's probably quite difficult to ram them hard enough without the right tooling as rubber is not conducive to being rammed. If they are at all slack the slop will be horrible not to mention it may fall out. The rubber is under substantial compression even at rest once in there in the effort to resist side to side slop.
 
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These are just beefed up chain tensioners with rubber " torsion bars". Easy to make yourself.

"Big box section" as frame. Small box section as "torsion bar",
The room in between filled with 4 pieces of "fitting" Oring
Thanks for this , found O ring cord with sizes all the way up to 30mm+

Looks interesting and £8 for 1 meter of 10mm ! Nitrile rubber

Paul
 
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