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Elements of Brass Instrument Construction:  Rotary Valves

Example of a set of rotary valves

Rotary Valves

Rotary valves were developed by 1818, when Friedrich Blühmel and Heinrich Stölzel, both from Berlin, were asked to include them in their valve patent. Further development took place in Vienna--in 1835 by Joseph Riedl, followed in 1843 by Leopold Uhlmann--to the point that eventually led to the modern form of rotary valve.

In rotary valves, additional tubing is added by the turn of a rotor (b) enclosed in an outer casing (a). The valve loops (c) and main tubing (d) are soldered to the outer case on the same plane. The port (c) of the rotor allows free passageway either to the main tubing or to the additional valve tubing.

German Rotary Valve with Clock Spring and Pin Stop

Parts of a German rotary valve (letters refer to diagram at right):

a = valve casing
b = rotor
c = valve loop with slide
d = main tubing
e = port
f = touchpiece
g = spring box with coiled clock spring inside
h = gear
i = articulated crank
k = push rod
l = rotor spindle or shaft bearing
m = pin stop
n = stop cork
o = valve cap
p = reciprocal driver pivot
q = screw to hold rotor in place

Typical German rotary valves with clock spring and pin stop.

Left: top view, first valve with pin stop, second valve open, third valve closed.
Right: section.

String Rotary Valves

While the connection between touchpiece and rotor takes the form of metal levers in German rotary valves, 19th-century American rotary valves used a string linkage. The first to make rotary valves with string linkage was Tomas D. Paine in Woonsocket, Rhode Island. In the second half of the 19th century, two different types of string-operated rotary valves can be distinguished:

  • Top-action, string-operated rotary valves in which the touchpieces are placed on top of the instrument, which is held vertically like a modern piston-valve trumpet.

  • Side-action, string-operated rotary valves in which the touchpieces are placed at the side, and the instrument is held horizontally in playing position like a modern German rotary valve trumpet.

String rotary valves come with a variety of different stopping mechanisms, such as the three-point-wing device with pin stop, the horseshoe-stop, and the V-shaped stop, which is a variation of the horseshoe-stop.

Top-Action, String-Operated Rotary Valve

Parts of a top-action, string-operated rotary valve (letters refer to diagrams at right):

a = valve casing
b = rotor
c = valve loop with slide
d = main tubing
e = port
f = touchpiece
k = push rod
l = rotor spindle or shaft bearing
m = pin stop
n = stop cork
o = valve cap
p = reciprocal driver pivot
q = screw to hold rotor in place
r = pulley
s = string
t = return spring
u = screw to hold the string in place

Top-action, string-operated rotary valve

Top-action, string-operated rotary valve, assembled and disassembled

Top:  Top-action, string-operated rotary valve with three-point-wing device and pin stop
Bottom left:  assembled.  Bottom right:  disassembled

Side-Action, String-Operated Rotary Valve

Parts of a side-action, string-operated rotary valve (letters refer to diagrams at right):

a = valve casing
d = main tubing
f = touchpiece
k = push rod
o = valve cap
p = reciprocal driver pivot
r = pulley
s = string
u = screw to hold the string in place
v = horseshoe-stop with cork buffers

Side-action, string-operated rotary valve, side view

Side-action, string-operated rotary valve, with horseshoe-stop

Top:  Side-action, string-operated rotary valve, side view.
Bottom:  Side-action, string-operated rotary valve, bottom view, with horseshoe-stop.

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