Tracker action

It was not until the mid-14th century that the action needed to be explored and expanded as finally more pipes were added, as well as the addition of stops, and ultimately multiple cases and keyboards.

The organ became larger and louder and pneumatically assisted action became the norm in large instruments, to offset the extreme key weight caused by high wind pressures.

Although tracker action was less utilized in the early 20th century, particularly in England and America, its use has enjoyed a strong renaissance in the same areas since World War II, especially in instruments modeled on historical antecedents.

Some active builders of tracker action organs include Taylor and Boody of Staunton, Virginia, Paul Fritts of Tacoma, Washington, Flentrop Orgelbouw B.V. of Zaandam, the Netherlands, and C. B. Fisk, Inc. of Gloucester, Massachusetts.

Steam calliopes, such as those built by Thomas J. Nichol in the early twentieth century, used a very simplified tracker mechanism.