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

[roadsailing]

drive by wire could be cool, but i dont know if you could control two slaves with one master (pedal)

could you rotate the shafts in the same direction?

ed, the picture you just posted wont work, that why i had the counter links either end of the watts links, in your design (and my first one) the movement will not be the same, as the ends of the watts links can move up and down, and should only move from side to side.

[ed]

toobs - i have an electronic throttle thingo on the 1uz at present... and id prefer to leave it in the milk crate i like direct activation of a cable

either way, it still doesnt overcome how to link the banks of throttles

[river]

Hi,

On your diagram above (with the blue link wires and the yellow plate) can't you remove the yellow plate and make the blue links two equal size flat metal plates that are joined by a pivot. You put a wire in the hole where the pivot is and when you pull on the wire the two plates get pulled down, where each would turn the shafts inwards (ie the plates pivot downwards, turnng the shafts as the do so). When the cable is released the plates comes back up and the shafts turn outwards. This depends upon some return spring to ensure the whole system comes back to its home position and to provide the required resistance to make it work (ie to take up the slack).

Do the shafts connect to anything, or are they just there to provide a movement assembly for the cranks? Are there more cranks on the shafts that connect, via cable, to the feul delivery system? What activates this assembly - is it a rotating thing or a simple cable that goes in and out?

When I know the answers to the above questions I maybe able to come up with a better solution. Then again, I may not. I need clarification first.

Sorry I can't draw a pic, my laptop (from work) has no drawing software.

seeyuzz
river

[gianttomato]

Isn't this

just really this

but with the central pivot tilted on its side? Won't this be taller, require more support and therefore be more bulky?

I think you're trying to reinvent the wheel. I'd go for a tried and tested method as they're proven to work!

The way I see it is there are two things you need to be worried about - making sure the two banks are activated to the same degree for a given movement of the central pivot and getting full throttle. The latter is easy - just a ratio thing. The other is only slightly more tricky.

If the crank on one of the throttle shafts is in a weird place, move it. Firstly, mock it up in craft wood and make sure you work some adjustability into it (use nice tight rose joints on two shafts just like that pic I posted). Then you need to make a tab for the throttle cable to fit into and it needs to have enough throw to fully activate the throttles. You also want to make sure it is sensitive enough at low throttle openings so you'll need to work out where to put it to achieve this (best place is "high" on the pivot). Make sure you have some kickass return springs - hopefully these are incorporated on the GTR throttle plates. If not, it would be a simple process to incorporate one into the central pivot.

Then, get it machined in 7 series and anodized.

[takai]

Ergh, the forum ate my post. Unless i accidentally killed it.

I was saying that i would be nervous about the vertical height involved in the setup you posted GT. The problem that i can envisage is that the shafts would need to be on the same horizontal plane as the rotational disc, higher and the shafts will foul on the disc and not let it get to WOT, and too low and the edge of the rose joints will foul on the disc. The other thing is that the height of the actuator needed to get proper movement out of the shafts would be quite detrimental to the precise controlling of the throttle at low throttle %ges.

Personally i think you had it right in the first place Ed. I did some maths, and if you up those distances a bit more, like 90mm apart (not sure how much room you have) it ends up settling down a fair bit. with a bit of jiggledypop you should get 1:1 or very close to it across 90% of the range. I guess the trick is to get that part which isnt 1:1 being at WOT where it doesnt matter much anyway.

[ed]

tak: i tried 90mm separation and got worse effects rather than better... what were your angular origins for the cranks when trialling the 90mm separation? same as mine (0 and 90deg) ??

dave: yes, what ive drawn is similar/same to your pic, but i will have the throttle being linked off the 2 shafts rather than off the centre bit directly. when i get a chance ill take some pics of the actual manifold etc

meanwhile i will persist with idea #1 yet some more...

[ed]

oh, as for reinventing the wheel... im not im trying to copy the f1 setup... and failing!!

[ed]

just had an interesting point raised:

is its all a bit academic trying to be pedantic and have the throttles PERFECTLY opening 1:1 if i can run equaliser tubes between runners to level out the minor differences???

perhaps i can use my linkage in its slightly crude, but functional form, and let each runner balance itself out amongst the others? i think it would work

[Ben Wilson]

If you wanted to gear it, any radio control car shop will have a large selection of high quality plastic gears at a good price..

[takai]

I wonder whether plastic or nylon gears would withstand the constant movement and the spring tension. Would be worth a try, especially given the price.

ed: i modelled it on 75mm with slightly offset cranks. I think the simulation i did would have binded at 90* on the trailing shaft. But i think offsettning the cranks gives a slightly more predictable movement. That and you negate some of the startup movement cost which would make low throttle percentages unbearable.
My simulation wasnt completely 1:1 but it was showing a trend towards it.

Oh yeah, the other thing is that i dont think it completely matters 100%. Sure its really nice but remember its only going to be 2 cylinders sucking in at the same time, and very rarely are you going to hold it at any one throttle position. But its always good to be as close as you can.

[roadsailing]

just read in PF its for a V8,



do it like this, drive the centre disc with the throttle cable, and set it up so the link rods are in tension (that si, so they pull the throttle open rather than pushing it open)

THis will result in a no-linear pedal travel to butterfly rotation, which could be good, If you set it up right (can draw a MSpaint picture) then you will have fine control at small throttle openings, and faster esponse at large throttle openings, so the throttle will essentially accelerate as you put your foot down at a constant rate, like a sine wave.

[ed]

porka's way of doing things:

[Ben Wilson]

If you're worried about non-linearity, you can always correct it with the bit which the cable pulls on (sorry I'm more eloquent when I'm sober - (I've just had a birthday lunch)

[ed]

happy birthday

no, not the slightest bit concerned about linearity. its about relative throttle plate rotation on the 2 banks of therottles connected by a linkage system

[Ben Wilson]

Thanks

Do you have any particular TBs in mind? If you ran them sideways the solution is really simple.

Otherwise, I think the sideways thing posted at the top of this page is the nicest solution.