Pneumatic tube coupling

Claim 1

Coupling construction for tube sections of a pneumatic tube system including, outturned flanges having outer edges and surfaces formed on adjacent ends of tube sections to be coupled; said outturned flanges being joined with the tube sections by annular fillets; a flexible metal band surrounding adjacent tube section flanges, the band having a central outer perimeter and two axially spaced series of circumferentially spaced inturned angular fingers extending from the central band portion; each finger being connected with the central band portion by a rounded bead-like portion and having a straight intermediate finger portion extending inwardly angularly from the bead-like portion; the intermediate portion having a reversely curved portion forming a shoulder portion, said reversely curved portion terminating inside of and spaced from the intermediate portion in an upwardly, outwardly extending straight end portion; the finger shoulder portions engaging the fillets of the adjacent tube sections; an elastomer gasket confined within the band and between the two spaced series of band fingers; the gasket including an annular internal surface, having a shallow troughlike configuration, extending around the perimeter of the tube section flanges; said gasket further including an annular flat base surface engaged by the flexible metal band, and spaced annular side edges extending between the base and trough-like internal surface; said gasKet side edges being engaged by the upwardly outwardly extending finger end portions, and said gasket trough-like internal surface being engaged by the tube section flanges outer edges; hose clamp means having a strap portion slidably engaged with the central outer perimeter of the flexible band and tensioned therearound; said clamp means imparting generally axial compressive forces through the straight intermediate finger portions between the finger shoulder portions and the tube fillets to press adjacent tube section flanges toward each other, and imparting generally axial compressive forces between the finger end portions and gasket side walls pressing the internal gasket surface against the tube flanges to form an airtight joint between the tube section flanges; and said clamp means imparting circumferential and radial compression forces between the tube section flanges outer edges and the trough-like internal gasket surface to form an additional seal between the tube section flanges.