Tekerölant is Hungarian for hurdy-gurdy: it literally means "turning lute", because the instrument is played by cranking and is shaped vaguely like a lute. But that name is a partial misnomer: it's not a lute at all (nor is it an organ, though people often associate the hurdy-gurdy with "organ grinders"): it's actually a mechanical violin!
Instead of a bow with hair being drawn across the strings to produce sound, the tekerö uses a wooden wheel, coated with rosin, to produce a continuous sound. Instead of fingers stopping the strings to get different pitches, the player uses a series of keys to press mechanical fingers (called tangents) against the string at the appropriate places.
(Because of all these mechanical doohickies, the tekerö has earned the official name of "The Contraption" in our band.)
Another Hungarian name for this instrument is nyenyere, which may be alliterative of the distinctive nasal tone of the tekerö.
A Little History
The hurdy-gurdy has been used as a European instrument since the 10th century. In Hungary the earliest references to the tekerölant are from the 16th century, at the very time when in Western Europe it was beginning to change from a "serious" instrument to one used by itinerant musicians, beggars and peasants. (Which pretty well describes the members of Danubius, by the way.) The tekerölant was played as part of the living Hungarian folk tradition until recently. It is now played by folk and medieval revival musicians.
How It Works
The diagram above shows the main parts of the instrument. The playing string (the one which can play different notes) is stretched between the bridge and a nut at the other end. (Of course, sometimes the nut is sitting underneath the instrument and cranking it.) The rosin-covered wheel is just in front of the bridge, and the string rests on the surface of the wheel so that it vibrates when the crank is turned. (Rosin is used because it's sticky and "grabs" the string, producing the vibration.) This vibration is transferred through the bridge to the wooden soundboard of the instrument.
To play different notes, the player presses wooden keys along the top of the tekerö. Each key pushes a tangent into the string; the tangent is a small wooden wedge which pinches the string against a wooden backstop at just the right spot to make the desired pitch (by shortening the vibrating length of the string).
Tekerö with cover open showing keys and tangents
The tekerö has 3 strings: one "playing" string and two drones. (For those familiar with bagpipes, think of the playing string as the "chanter".) The playing string is tuned to E and the two drones to A, an octave apart.
The drones have more special doohickies associated with them: both of these strings have small auxiliary bridges attached to them. These little bridges have a loose "foot" that can beat against the soundboard, so when the player gives the crank an extra fast impulse, they produce the rhythmic buzzing sound which is characteristic of the hurdy-gurdy.
Because of the rather crude tuning pegs found on most hurdy-gurdies, this instrument falls into the same class as the harp: as the old musician's joke says, the player spends half their time tuning it, and the other half playing out of tune.