• 14 parts
  • Checked September 2026

Parts of a French Horn

A double French horn from the front, with one of its rotary valves taken apart.

Parts of a French Horn

Name Date

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1 2 3 4 5 6 7 8 9 10 11 12 13 14
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Write the name of each numbered part.Answer key

  1. Mouthpiece
  2. Leadpipe
  3. Bell
  4. Rotary valves
  5. Valve levers
  6. Thumb key
  7. Main tuning slide
  8. F slides
  9. B-flat slides
  10. Water key
  11. Stop arm
  12. Valve casing
  13. Rotor
  14. Valve cap

Drawn for this site on 2026-09-30 from plain geometry. Licence: own work.

Each numbered ring is a button. Use the arrow keys to move between them and Enter to choose. Names are read out in Study, and once a part is answered.

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All 14 parts on the diagram

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Tubing and bell 4

  1. Mouthpiece Where the player's lips make the sound.
  2. Leadpipe The tube the mouthpiece is placed in.
  3. Bell The large flared end. The player's right hand rests inside it.
  4. Water key Pressed to let out water that gathers in the tubing.

Valves and levers 7

  1. Rotary valves Each one turns to send the air through extra tubing.
  2. Valve levers Pressed with three fingers of the left hand to turn the valves.
  3. Thumb key Works the fourth valve, which switches between F and B-flat tubing.
  4. Stop arm Fixed to the top of the rotor. The lever turns it.
  5. Valve casing The fixed drum the rotor turns inside. Tubes join its ports.
  6. Rotor It turns inside the casing. Its passages send the air another way.
  7. Valve cap Screws onto the casing to close the valve.

Slides 3

  1. Main tuning slide Moved in or out, it tunes the whole horn.
  2. F slides The longer slide of each valve, for the F side.
  3. B-flat slides The shorter slide of each valve, for the B-flat side.

How this list was compiled: Every name checked on 2026-09-30, a name kept only where two independent sources use it for this part. (1) Wikipedia, text only: French horn (its numbered scheme of a double horn: mouthpiece, leadpipe, water key, fourth valve to switch between F and B-flat, valve levers worked by the left hand, rotary valves, a slide for each valve, tubing for F and for B-flat with slides, general slide, bell with the right hand inside; the thumb key and lever keys), https://en.wikipedia.org/wiki/French_horn ; Rotary valve (valve casing, internal rotor, rotor spindle, valve cap), https://en.wikipedia.org/wiki/Rotary_valve ; Leadpipe, https://en.wikipedia.org/wiki/Leadpipe ; Water key, https://en.wikipedia.org/wiki/Water_key . (2) An instrument maker's online Musical Instrument Guide, The Structure of the Horn (its part list for the F and B-flat double horn: bell, leadpipe, mouthpiece, main tuning slide, first to fourth rotary valve, F tube and B-flat tube first to third slides, first to third lever, fourth lever for switching between F and B-flat; levers worked by the left hand), https://www.yamaha.com/en/musical_instrument_guide/horn/mechanism/ . (3) Clayton H. Tiede, The Practical Band Instrument Repair Manual (1970), searched in full text at https://archive.org/details/practicalbandins00tied (French horn rotary valve: stop arm head and its screw, the valve, the bearing unit, the valve cap, key lever, string; main tuning slide, water key, mouthpipe). (4) Clifford Bevan, The Tuba Family (1978), searched in full text at https://archive.org/details/tubafamily0000beva_y3y3 (its figure of a rotary valve: rotor, casing, stop arm head, valve cap). (5) Jeremy Montagu, The French Horn (1990), searched in full text at https://archive.org/details/frenchhorn0000mont (rotary valves, rotor, tuning slide, mouthpipe). Licence: own work

The drawing: Drawn for this site on 2026-09-30 from plain geometry; no maker's instrument, nothing traced. Licence: own work

How it works

A French horn is a long coiled tube with a mouthpiece at one end and a wide bell at the other. Start with the coil and bell, then the valves, levers and slides in the middle.

Read the full guide

Two views, coil to valve

Numbers 1 to 10 are the whole horn: mouthpiece, leadpipe and bell, then the rotary valves, the three valve levers, the thumb key and the slides. Numbers 11 to 14 are one rotary valve taken apart: stop arm, casing, rotor and cap.

Why there are two sets of slides

This is a double horn: two horns in one, a longer one in F and a shorter one in B-flat. The thumb key works a fourth valve that switches between them. Each of the three finger valves has a slide for each side.

  • The left hand works the levers. The right hand goes inside the bell.

Questions and answers

What are the main parts of a French horn?

The mouthpiece, the leadpipe, the main tuning slide, the rotary valves with their levers and slides, the long coil of tubing and the bell. A double horn adds a fourth valve worked by a thumb key.

How does a rotary valve on a horn work?

Pressing a lever turns a rotor inside the valve casing. The passages in the rotor then send the air through the valve slide, an extra length of tubing, which lowers the note.

What does the thumb key on a French horn do?

On a double horn it works the fourth valve, which routes the air to the tubing tuned to F or to the tubing tuned to B-flat.

Why do horn players put a hand in the bell?

The right hand helps hold the horn, and its position in the bell can raise or lower the pitch of a note.

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