page_title: Tracker action
section_title: Components of the action
hierarchical_section_title: Tracker action / Components of the action
caption_attribution_description: English: View of the tracker action immediately inside the organ as viewed from the console.
context_page_description: Tracker action is a term used in reference to pipe organs and steam calliopes to indicate a mechanical linkage between keys or pedals pressed by the organist and the valve that allows air to flow into pipe of the corresponding note. This is in contrast to "direct electric action" and "electro-pneumatic action", which connect the key to the valve through an electrical link or an electrically assisted pneumatic system respectively, or "tubular-pneumatic action" which utilizes a change of pressure within lead tubing which connects the key to the valve pneumatic.
context_section_description: 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 10 mm 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 (in the sense of "pull"); cf. modern English tractor.
  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 250 mm.
  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.
caption: Interior of the organ at Cradley Heath Baptist Church showing the tracker action.  The rollers transmit movement sideways to line up with the pipes.
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