Tracker Action - Components of The Action

Components of The Action

The action consists of many types of devices used for the playing of such said organ, as listed below:

• Trackers – trackers are the portions of the action used to make a pulling motion. Trackers can be used over long distances. They are thin strips of wood, roughly 1 cm wide and 2 mm thick. Although flexible, at rest they hold their shape. Playing a note pulls on the end nearer to the keyboard, so they are in tension while the note is playing. The term comes from the Latin verb "trahere", to draw (pull).
• Stickers — used for a pushing motion; often paired with trackers. Their length is limited by the material, though most of the time, capping off at about 10 inches.
• Levers — levers are used to transfer from a tracker (pulling) to a sticker (pushing), or a general change of direction, or both.
• Backfalls — backfalls are used for motion over a small or short distance where trackers and stickers would be otherwise illogical to use. As a natural result, the motion also changes direction.
• Squares — a specific type of lever commonly used in organs which is at a right angle. Squares can also come in a "T" shape and form.
• Rollers — Wooden shafts that rotate. Used for parallel direction in vertical or horizontal motion. They have small levers on each end, like cranks.
• Roller board — location upon which rollers are attached (Note: rollers are often used densely in one section of the action and so are often closely associated with the roller board.)
• Stops — knobs that indirectly control the flow of air over certain ranks of pipes. They are activated with a pulling motion by hand, and deactivated (or stopped) by pushing them shut.
• Trundle — Trundles are used as a substitute for levers in the action associated with the Stops and Slider boards.

The above is a list of mechanisms unique to tracker action. Steam calliopes, such as those built by Thomas J. Nichol in the early twentieth century, used a very simplified tracker mechanism. For actions used in all forms of pipe organs, see pipe organ construction.