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Pipe Organs and Related Topics <[log in to unmask]>
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Fri, 26 Feb 1993 10:03:42 -0500
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Bobby, your questions about the unified mechanical action key channels
should probably be answered by Allan Ontko or someone else who has
*actually built one*, but here is a quickie attempt to draw the scheme.
 
The following is a view up onto the bottom of the key channel grid.
It shows the paired channels for a given note; in this case, for the
HW and the (one octave lower) PED.  You have to imagine that the
two pallets are transparent and hinge at the right.  The "====" are
the channel bars and the "|" are the ends of the divider strips that
run "up" the channel, ending between the toe holes for each pipe.
Yes, the bottoms of these dividers reach the pallet and so the pallet
closes off all of the sub-channels or opens them all.  I think it is
common practice to have the bottom openings of each sub-channels of
varying lengths, with those nearer the pallet pivot being longer since
the pallet opens much less at that end.  (They might also be of
different sizes depending upon the wind requirements of the their pipes.
 
    +---------------------------- HW 4' Prinzipal (in facade)
    |    +----------------------- HW 8' Gedackt
    |    |     +----------------- HW 2' Spitzfloete
    |    |     |      +---------- HW    Mixtur
    |    |     |      |       +-- HW 8' Trompette
    |    |     |      |       |
  +====+=====+======+=======+========+
  |    |     |      |       |        | HW Pallet covers all of these.
  +====+=====+======+=======+========+
  |    |     |      |       |        | PED Pallet covers all of these.
  +====+=====+======+=======+========+
    |    |     |      |       |
    |    |     |      |       +-- PED 16' Trompette
    |    |     |      +---------- PED     Mixtur
    |    |     +----------------- PED  4' Spitfloete
    |    +----------------------- PED 16' Gedackt
    +---------------------------- PED  8' Prinzipal (in facade)
 
Just how the dividers are attached might depend upon the builder's
personal preferences.  It would be easiest to glue them with butt
joints to the channel bars, but leakage could be a problem.  With some
fancy jigs (and perhaps a router with a very small grooving bit) you
could slide them into slanted grooves in the side of the bars.
(Allan, HELP!)
 
I've seen this scheme documented for a number of modern, mostly German,
trackers.  Sometimes, they use these dividers even when there is no
unification; the dividers serve to prevent certain undesired interactions
between certain ranks.  Often, it is the reeds that are separated.  (That
is itself an interesting subject, since one of the historical claims for
slider chest superiority is the acoustical coupling of pipes on a
common channel.)
 
Oh, well, that is probably more than anyone wants to know about penguins!
 
Larry Chace ([log in to unmask])

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