Assertion: valve's spring | /r/CapableOf | aid in spiral rotation of said piston
Facets:
Source sentences:
text: A valve structure for cupped mouth musical instruments having spirally operat ing piston means involved in the structure, an inverted conical spiral spring connected to react longitudinally and torsionally to aid in the spiral rotation of said piston.
text: A valve structure for cupped mouth musical instruments having spirally operating piston means involved in the structure, a spiral spring connected to react longitudinally and torsionally to aid in the spiral rotation of said piston.