how to make two shafts rotate together... ???

[takai]

It shoudl be a 1:1 but cable driven stuff is always nasty, and has a tendency to flick the cable when you come suddenly off throttle. Especially if one set of throttles closes faster than the other. Thats why mechanical linkages always rule.

Ill have a go at modelling it today in one of the cad programs i have here, see what i come up with. Its only 2DOF though, so it shouldnt be overly complex.

[The Last Streetfighter]

http://pergatory.mit.edu/2.007/lectu...d_Triggers.pdf
Takes me back to 2nd yr Mech Eng....

[Hen]

Good point Takai. Maybe adding a second cable would help, so one is always under tension and so neither can get slack enough to jump out of their groove. And also they should always be held in the same relative position, regardless of relative spring strength etc..

Like this:


But having another look at that, it would require two discs per shaft so that the cables don't rub on each other where they cross

Hen

[Nim]

Yeah I was thinking that setup Hen.

Perhaps a better setup would be a sliding gear? Two round gears, with a solid sliding gear in between? The motion would then be 1-1 without having to worry about angles changing as you throttle up.

But then you gotta make up a a rail for the slide gear, and get two gears to match etc.

[Bored?]

Two thoughts:

1. For the "centre disk" linkage approach, you could also have the disk rotate on an axis parallel to the shafts.
2. A really elegant approach would be to simply put a gear on each shaft, or even 4 gears if you need more space between the throttle bodies. You'd need to watch tooth spacing, and helical gears might be nice to.

[roadsailing]

put a watt's link between the two, basically the same as the disc in the middle link system, but they all rotate through/in the same plane.

(just realised this is just what bored said)

i'd draw a picture, but i'm not goot at MSpaint.

[wilbo666]

put a watt's link between the two, basically the same as the disc in the middle link system, but they all rotate through/in the same plane.

(just realised this is just what bored said)

i'd draw a picture, but i'm not goot at MSpaint.

That is pretty well exactly what Ed showed in his first post...however the ratio isn't 1:1 throughout i.e. both banks of throttles do not open the same amount...not the best thing...



Cheers
Wilbo

[Nim]

Two thoughts:

1. A really elegant approach would be to simply put a gear on each shaft, or even 4 gears if you need more space between the throttle bodies. You'd need to watch tooth spacing, and helical gears might be nice to.

Oooooh... that's a good idea. Do that.

[ed]

[*] A really elegant approach would be to simply put a gear on each shaft, or even 4 gears if you need more space between the throttle bodies. You'd need to watch tooth spacing, and helical gears might be nice to.[/LIST]

this was the $97 each solution i was referring to in the first post. itd work, but id prefer to try and make a linkage system work first...

http://www.minibearings.com.au/cgi-b...ic&Step=3=post

[wilbo666]

Do you really need Helical gears? lol

Bah, just go find a mill and an indexing head and make your own gears? lol

I like GT and oldcorolla's idea...sure it won't be linear...but is the accelerator pedal linear either? It will give 1:1 to each bank tho...

Cheers
Wilbo

[ed]

nah, not quite what i said. this new idea is introducing another linkage system betwen the shafts,itself rotating on an axis parallel to the shafts...

currently this idea has the most merit

That is pretty well exactly what Ed showed in his first post...however the ratio isn't 1:1 throughout i.e. both banks of throttles do not open the same amount...not the best thing...

[Nim]

Sorry about the low quality.
That's my idea.

[roadsailing]

thats even more complex than two gears, and gears = slop.

EDIT: it will also make both shafts rotate in the same direction

here is my watts link design, didnt turn out like i first thought it would, as my first idea would only work if the shafts rotated in teh same direction. not sure if this one would work too well either.



if you use an intermediate mechanism, make sure you drive both shafts from the mechanism, and drive the mechanism (in the sentre in this case) with the throttle cable.

[Toobs]

Have you looked at electronic throttle controllers?
You might be able to swap the TPS with such an item and control it with an aftermarket ECU... assuming you were going to go aftermarket this time.
The Prius, 2k5 Camry, 2k5 Avalon and a few other models might be a good place to start looking if you were willing to consider this.

[ed]

this is the idea thats leading the way at present although id REALLY like the single link idea to work somehow)...

the centre yellow crank is in the same plane as the main shafts. bit hard to get the perspective right with a touchpad...