Abstract: A ring shaped seal is formed from an elastomeric material and is generally circular in cross-section. The material is covered in part with an elastomeric impregnated fabric secured thereon which serves as a work contacting surface for making a sealing engagement with a surface on a duct. A tubular ring shaped insert formed from an elastomer is embedded in the seal. A ring shaped spring is movably mounted in the bore of the tubular insert in such a way that the spring is not bonded to and does not adhere to the walls of the tubular insert. The insert is mounted in the seal so the walls of the tubular insert are between the spring and the elastomer impregnated fabric to hold the spring away from the fabric to prolong the life of the seal. The spring is sized so when the seal is mounted on the duct the spring can move in the bore of the tubular insert and exert a compressive force on the seal to compensate the seal for the decreasing resilience of the elastomeric material forming the seal.

Abstract: A rubber ring-shaped seal is provided with a centrally disposed ring-shaped elastomeric tubular insert mounted therein. A helical coil spring is mounted in the insert so that part of the ring-shaped insert is between the helical coil spring and the work-contacting surfaces of the seal. The seal is mounted on formations formed on a tubular housing which serves as a connector. These formations define seal-receiving channels which position the seal rings in the housing.

Abstract: A test circuit for testing electrical characteristics of heating elements and switches coupled to individual elements. The switches are manually operated and conventionally may be mounted on a cooking range panel. The switches are operable to place the elements in an energized state wherein they are coupled to an electrical power source and in a deenergized state wherein they are decoupled from such source. The leads from the switches are typically coupled to the leads from the heating elements through a multi-conductor coupling harness wherein one harness segment has a plurality of male connectors and the other harness segment has a plurality of female connectors engageable with the male connectors. A T-connector has a first set of connectors engageable with the male connectors and a second set of connectors engageable with the female connectors and a third set of connectors coupled with the leads of a test circuit.