This is another article I came across which was published in Soundboard (the Church of Ireland Dublin Diocese Magazine):
Organ - What's Inside a Pipe Organ?
In the first few issues of Soundboard, Stephen Adams has explained some of the issues regarding the workings of pipe organs. We had received requests for some explanation of why organs cipher. With a view to more explanations in further articles, this detailed drawing from J. W. Hintort’s book “Organ Construction” (3rd edition 1910) is reproduced. Reference will be made to it in later articles.
The cross-sectional view (from front to back) of a typical tracker organ is shown, and also the general appearance and location of the pipes belonging to the different stops.
All organists should have some knowledge of just what is behind what can be seen — which is generally only the console and the front display pipes. Referring to the diagram, the 3-manual keyboard is at the bottom left-hand corner. Directly behind this is the bellows or wind reservoir. Above the reservoir arid behind the front display pipes is the Great Organ — the various ranks of pipes standing on the Great soundboard. Behind the Great are two Passage Boards (walkways) at different heights, to provide access to the Choir Organ (at the same level as the Great) and the Swell Organ (at the higher level) — the Swell Organ being enclosed inside a box with louvred openings. Notice the bottom pipes of the 16 foot Swell stops are “doubled up” so that they will fit inside the box. At the very back, behind the Choir Organ, is the Pedal Organ.
Note that while the diagram shows the key action (how depressing a key allows wind into the pipe), it does not show the stop action, nor the trunking (how the wind is conveyed from the reservoir to the soundboards.
For the smaller number of readers who are interested in the technicalities, the letters of the sketch refer to the following:
A feeder
B backfall beam or stock
C square
D bayleaf
E boot
F conveyance
G groove board
H slots
I stickers
J backfalls
K purse board
L tracker
M pull down
N pallet
0 bellows ribs
P imposts
Q wind bar
R face board
S table
T slide
U upper or cover board
V register
W rack pillar
X rack board
Y swell louvres
Z pedal tracker
AB bellows
BC roller board
CD tuning clips
DE tuning slide
