Tracker (organ)
Thin wooden strips or wires that connect keys and valves in mechanical organ actions.
What it means
Trackers, called Abstrakten in German, are the thin wooden strips or wires that transmit the motion of the keys to the valves of the windchest in a mechanical organ action. They form the link between the keyboard and the pallets that release the flow of air to the pipes.
Musical use
When a key is pressed down, the tracker pulls or pushes, via rollerboards and squares, to open the corresponding valve, allowing wind to flow into the associated pipe. The length of the trackers depends on the physical distance between the console and the windchest and can vary widely depending on the organ's construction.
Other names
A mechanical action built on trackers is also called tracker action, as opposed to pneumatic or electric actions, which dispense with such mechanical connecting pieces.