Dual proportioning throttle linkage

Here we have another one of those clever bits that you’ve maybe heard about but never given thought to. Maybe we need a better name… but this linkage will allow one pedal to control two throttles, at any ratio. Useful for woodgas under carb setups.

Max Gasman posted this a few weeks ago:

"Hi, Tyler!
Panic: One gaspedal, One brakepedal on the floor!
Convenience: On dash

  1. 100% – 50/50 – 100% stepless woodgas/gasoline lever,
  2. gasoline <–> woodgas timing lever,
  3. common idle adjustment (“handgas”), follows the fuel selector.
  4. woodgas/air fine adjustment

These adjustments will cover “all” your needs…
The gasoline carburettor adjusted without any “own” idle; getting needed idle adjusting through the common idle adjustment. This way no gasoline is used when total woodgas is chosen."

So, I asked Max about it, and he sent me the drawing below (1st pic). I thought I had it figured out, so I decided to build a model from the kid’s LEGOs. Video here, photo below (2nd pic). http://youtu.be/tvQZ15NYSi4

The one thing I haven’t quite figured is how the slider valve can attach to a cable. In my model at least, there’s too much swinging motion to attach anything solidly.

Another drawing of this type of linkage comes from Kurt Johannsen in Australia, many years ago (3rd pic). I don’t think his will work as smoothly as it depends on identical spring rates from the throttles. But he obviously found it worthwhile.

Good work Chris! Nicely done.

Sean French had a neat mechanism on his 70 kW 3 phase GMC powered generator. I seem to remember two sprockets with a chain drive…(I can’t find that video.) Your LEGO demo reminds me that the windshield wiper assembly fell apart under the cowl of my 1990 Dodge. I have new wiper bushings but it is a bit cool to go out there and crawl up on top of the engine and reach through some itty-bitty slots to put them on…