Axial flow valve

The axial flow valve, or Thayer valve, is a brass instrument valve design patented in 1978 by American inventor Orla Ed Thayer. Designed with assistance from instrument maker Zigmant Kanstul, it was originally intended to replace the traditional rotary valve on the French horn, but instead revolutionized the design of trombone valve attachments. Combined with open-wrap tubing, it eliminates the impedance caused by tight tubing bends, improving the airflow through the instrument and the open "feel" perceived by the player.