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Elements of Brass Instrument Construction:  Allen Valves

Allen valve

Allen Valves

This valve type is characterized by long slender rotors; the tubing entering and exiting the rotor is flatter and longer than a normal rotary valve. Its design is attributed to Joseph Lathrop Allen, a Boston brass instrument maker, who produced his first valves of this type sometime after 1853. Allen's intention was to create a quicker action by reducing the diameter of the rotors. Its seemingly effortless movement helped the Allen valve become quite popular among 19th-century American players.

Allen Valve Mechanism

Valve construction seen from the left side

Allen valve mechanism

Parts of an Allen valve (letters refer to diagrams above and below):

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 string in place

Allen Valve Case Diagram

Allen valve case

Right:  Arrangement of closed valve case
Left:  Valve disassembled (from right to left):   rotor with cork buffers inside; disc with stopping protrusion; rotor spindle nut with attached reciprocal driver pivot; topping screw

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