Posted by Klaus on November 06, 2001 at 12:05:36:
In Reply to: Re: Re: Re: Berlioz Te Deum ... Saxhorn Parts????? posted by Erik on November 06, 2001 at 11:13:58:
My understanding is, that they appear like a two story milled rotor as known from rotor valves. Only that the motion is up and down like the hollow pistons, that we also are so familiar with.
The problem with the rotors are, that thre has to be 2 milled windways in each "story" (French horns have up to 3 "stories"). That leads to some distortions of the general windway. By profile as well as by sharp angles compared to imaginary "straight through" ideal.
In the Berliner Pumpen cav have a traight thorugh option in its lower story. When it is pushed the upper story comes into action. And then it is not bound by being perpendicular to the open option.
That gives a smoother, less sharply angled windway.
One can seea parallel in the typical US front action tuba and sousa. Try to follow entry in and exit from the valve loops. They are rather 135 degrees than 90 degrees to the main direction throught the valves.
As this needs the valves loops to have eexits and entries on each side of the pistons, this description does not fit the 2nd valves, because they have too short valve loops to reach around the pistons and be pullable at the same time.
(Written in a hurry. Please ask on!)
Klaus