Humming top
The humming top is a nostalgic tin toy . The company Lorenz Bolz in Zirndorf, which had existed since 1880, patented the drill rod in 1913 . With this invention, the classic string top was replaced.
A metal rod with a wooden handle (now mostly made of plastic), around which helical grooves wind like a screw, is pressed into the top . The gripper engages in the recesses in the rotor head. The thread turns the gyroscope, which continues to turn even when the screw spindle is raised again, as a free wheel is formed.
By pumping again the top is accelerated, and the faster it turns, the louder it “sings”. This is made possible by small incisions that are made where the sheet metal body of the gyroscope is largest. As soon as the top rotates, the air is thrown out of its interior by centrifugal force . At the same time, air flows in through openings below the base of the top to compensate for the negative pressure created in the top. The small metal tongues attached to these holes vibrate through the air flow and make the top hum.
There are various tops, so-called chorale tops , in which, similar to a harmonica , reeds with different pitches are attached. A loosely lying cardboard disc, which is provided with slots, alternately releases reeds by rotation with the reduction gear. Such a choral gyro can produce up to 20 different tones and play simple children's songs. This type of top was also invented by the Lorenz Bolz company. The reduction gear was patented by Bolz in 1937.
