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Post up a thread for your EV. Progress pics, description and assorted alliteration
jpcw
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Post by jpcw » Tue, 31 May 2011, 19:18

Girder does seem to be the choice for strength. Not as comfortable a ride according to the NCOP15 Trike Guidelines but is probably the simplest choice, probably be the one I go with as well. Just got to decide if I make it myself or get one in kit form. You will have to let me know how yours turns out.
“The best way to predict the future is to invent it,” Alan Kay 1971

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Post by EV2Go » Tue, 31 May 2011, 19:44

Well if you want to PM me an email address I can send you a zipped copy of the CD / DVD it's only 18Mb. Have a look and decide for yourself whether you think your up to it.

It's complex (as in you need to be very accurate) but simple at the same time... I don't know if the ride would be all that bad, but the manual tells you that you need to get things right for it to work well.

It has a smaller window for error than most designs, but has the greatest of rewards when you get it right (or so they say).

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Post by EV2Go » Fri, 03 Jun 2011, 00:57

Today I took a few still images off the video I sent you the link to, since it was coincidently very close to my SketchUp designs I sent you (think he was looking over my shoulder). Just seeing it in raw steel instead of my 3D model gave me inspiration to go in another direction.
I am now thinking a cross between the duolever and a girder. Will try put a mock up together.

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Post by EV2Go » Fri, 03 Jun 2011, 04:04

ok so here's what I'm thinking... it's a cross between a girder and a duolever. This design would cut a lot of material out of the top and bottom neck brackets.

More importantly if you plan to have a wide frame front to your trike like I am (roughly 10"-12" for the controller width) if the brackets on the top and bottom neck brackets stick out wide, they will quickly foul the frame, limiting steering turn.

By having the single pivot point at the frame end the wider bulk sits well away from the frame. Also I think this will give the front a cleaner look.

This is obviously not a finished design, but a quick modded version of one of my eariler designs.

Right Pic: see how in my frame picture the neck brackets might hit the frame.

ImageImage

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Post by EV2Go » Fri, 03 Jun 2011, 04:33

First revision... to avoid any binding issue with diagonals, back to right angles but change the A arm.

Image

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Post by EV2Go » Fri, 03 Jun 2011, 06:44

Further refinement and a more complete mock up... here were have one of the later versions I created, and a same way, and a reverse way of the bottom.

You will note in the second pic a support rod between the two top links, this is an attempt to stop the links wandering sideways, by boxing the links it makes it effecively solid.

The newest design has this built it by virtue of the triangulation.

ImageImage

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Post by EV2Go » Fri, 03 Jun 2011, 07:10

Just found a significant flaw in the design... when turning there is nothing to force the head to turn like when the triangle is the other way around Image and it was looking so promising.

Only way I can see around it is to remove the swivel from the neck altogether and have ball joints direct on frame.
Last edited by EV2Go on Thu, 02 Jun 2011, 21:11, edited 1 time in total.

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Post by EV2Go » Fri, 03 Jun 2011, 16:03

Gave this some more thought as I was falling asleep... In a typical telescopic forks the steering neck is roughly between the fork legs, when you turn the handle bars the forks rotate around the neck (one fork back one forward).

In a springer or girder where the links effectively move the front wheel / steering pivot point forward 4 or 5 inches, the front wheel arcs rather than turning on the same spot. Being so far forward of the steering neck when you apply steering turn, one fork leg will go forward but the other may still be ahead of the steering neck...

Which brings me back to my point... if I put both top and bottom ball joints on the frame, that is setting the frame as the turning point and the A arms move the wheel centreline away from the steering point the
same as girder.

If the A arms are flipped around like the duolever, the ball joints are roughly back in the centre of the fork legs again like the telescopic. Since my frame is already going to be wide (and yours might be too if you are running batteries there) it almost makes sense to use this frame width and put the ball joints out front and do away with a steering neck.

With the point of the triangle out front it should still provide very good steering turn. So where does this leave us from a design / engineering stand point...

Well fork engineering couldn’t be easier just imagining drilling a hole/s for a ball joint between the two fork legs. Fabricate some simple A arms in a jig. The tricky bit is fabricating the pivoting steering brace to move the steering.

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Post by woody » Fri, 03 Jun 2011, 16:28

It seems you're not alone in struggling with bike design...

Science doesn't know what keeps a bicycle upright
Planned EV: '63 Cortina using AC and LiFePO4 Battery Pack

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Post by EV2Go » Fri, 03 Jun 2011, 16:50

Glad I'm not trying to engineer something as complicated as a bicycle Image

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Post by EV2Go » Sat, 04 Jun 2011, 06:19

Some fresh pics straight off the SketchUp pad... I'm nearly tempted to move away from the girder idea and use this design myself.

With no neck to speak of, you would need to set the rake angle in the frame. (no shock or steering mechanism shown)

Edit: where ball joint goes in I would be inclined to make that flat, instead of angled like shown.

Image
ImageImageImage
Last edited by EV2Go on Fri, 03 Jun 2011, 20:23, edited 1 time in total.

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Post by EV2Go » Sat, 04 Jun 2011, 08:47

I switched out the girder front end on one of my mockup trikes for the new duogirder front end to get a feel for the look.

Some interesting findings... the steering neck could be placed in the middle of the top A arm, bringing the forks closer to the frame (and keeping the wheel base down).

The shock / coilover top could be mounted directly under the shortened steering neck so the shock and the front wheel turn together like on the girder.

With the frame not having to come to a point for the steering neck, it opens up more space up front for greater parts storage. I actually prefer the look of the new front end...

Image

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