Re: rotary valves


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Posted by Art H on August 25, 2003 at 22:48:24:

In Reply to: rotary valves posted by david on August 25, 2003 at 22:12:47:

To make rotors fast you must either reduce their mass (by making them hollow or by making them out of a lighter material) or increase the spring tension and strengthen your fingers. But you can also make them FEEL less sluggish by changing the mechanical advantage of the linkage to make the spatula stroke longer. It's like shifting gears on a bicycle. Long stroke means less effort needed. The valves then seem lighter and faster, more like pistons. I have done this with string-action rotors (on a Cerveny) by increasing the diameter of the shaft that the string wraps around on the rotor. I have also done it on ball-and-socket linkages by moving the ball on the rotor end of the pushrod a bit farther from the center axis of the rotor, or by moving the ball at the other end a bit closer to the axle that the spatulas turn on. I also find it helps to lengthen the first valve spatula, so that it meets my index finger.
When a student complained to Harold Brasch that the long-stroke Besson pistons were slowing him down, Brasch had this to say: "Oh? ...You can play fast?"


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