A sealing device includes an elastic annular seal portion. On an inner peripheral surface of the seal portion, a main lip is in slidable contact with an outer peripheral surface of a rotary shaft, and a vacuum space side inclined surface gradually enlarges in diameter from the main lip toward a vacuum space side. On the vacuum space side inclined surface, a first annular projection is in slidable contact with the outer peripheral surface of the rotary shaft, and a second annular projection that projects toward a radially inward side is disposed between the main lip and the first annular projection. In an initial use state of the sealing device, the second annular projection is not in slidable contact with the rotary shaft; when the main lip wears to a degree that required sealing performance cannot be maintained, the second annular projection starts slidable contact with the rotary shaft.

Actuators and methods utilizing electrical properties of polymer materials. The actuators have a multilayer structure that includes an electroactive polymer layer between and bonded to first and second electrodes so that the polymer layer has a thickness dimension therebetween. The multilayer structure is adapted so that application of an electric potential to the electrodes causes the electroactive polymer layer to expand in at least one dimension thereof transverse to the thickness dimension of the electroactive polymer layer. The actuators can be used in sealing elements to provide a resealing capability once a condition has occurred of a type that may precede a seal failure.

A seal structure is provided to block a clearance between a rotational casing and a fixed housing for driving a crawler of a crawler vehicle. A seal ring is held in a first annular holding groove provided in the fixed housing together with a first O-ring that biases the seal ring toward the outside of the first holding groove. A second holding groove having an opening facing the first holding groove is provided in the rotational casing to hold a slide ring having a higher rigidity than that of the seal ring together with a second O-ring that biases the slide ring toward the seal ring. A foreign object such as mud is thereby prevented from invading a gear chamber without increasing a frictional loss.

A seal system includes a face seal rotor ring including a wide sealing face preferably made of tungsten carbide. The stator ring includes a narrower sealing face confronting the rotor ring wide sealing face. The stator ring sealing face is preferably made of polyamide-imide and tapers to narrower widths rearwardly.

A seal structure is provided to block a clearance between a rotational casing and a fixed housing for driving a crawler of a crawler vehicle. A seal ring is held in a first annular holding groove provided in the fixed housing together with a first O-ring that biases the seal ring toward the outside of the first holding groove. A second holding groove having an opening facing the first holding groove is provided in the rotational casing to hold a slide ring having a higher rigidity than that of the seal ring together with a second O-ring that biases the slide ring toward the seal ring. A foreign object such as mud is thereby prevented from invading a gear chamber without increasing a frictional loss.

A system seals a filter or equipment component to abase and will continue to seal the filter or equipment component to the base in the event of hot air or fire. The system includes a first sealing material between the filter or equipment component and the base; and a second sealing material between the filter or equipment component and the base and proximate the first sealing material. The first sealing material and the second seal material are positioned relative to each other and relative to the filter or equipment component and the base to seal the filter or equipment component to the base and upon the event of fire the second sealing material will be activated and expand to continue to seal the filter or equipment component to the base in the event of hot air or fire.

A seal section for use in a downhole submersible pumping system includes one or more fluid separation mechanisms, a shaft and one or more primary mechanical seals. Each of the one or more primary mechanical seals is disposed along the shaft. The seal section also includes one or more redundant shaft seals that each substantially surrounds a corresponding one of the one or more primary mechanical seals. In another aspect, a seal section for use in a pumping system includes one or more fluid separation mechanisms, a shaft, a primary mechanical seal and a redundant shaft seal. The redundant shaft seal substantially surrounds the primary mechanical seal. The seal section further includes an internal seal chamber defined by the annular space between the primary mechanical seal and the redundant shaft seal.

A seal arrangement allowing in-line maintenance and replacement of packing, seals and bushings of a rotary shaft driving a tool extending inside a fluid holding tank. The rotary shaft and associated seals are mounted in an extractable cartridge removably insertable in sealing engagement within a housing projecting outwardly from the tank. A secondary seal comprises an isolation valve mounted to the housing outside of the tank for temporarily providing sealing during servicing of the seals in the extracted cartridge. A tertiary seal is provided for protecting the secondary seal from the tank contents when used in scaling environments. Removable parts of said seal arrangement

This leakage prevention seal is provided with: a first seal ring which surrounds a rotating shaft and which is in circumferential contact with the surface of a housing which faces the upstream side; a second seal ring, which, on the upstream side of the first seal ring, surrounds the rotating shaft and which is in circumferential contact with the first seal ring; and a heat-driven section which, when high-temperature pressurized water reaches the heat-driven section, reduces the diameter of both the first seal ring and the second seal ring and causes the inner peripheral surfaces of both the first seal ring and the second seal ring to be in contact with the rotating shaft. The circumferential positions of both a first range between the first seal ring and the rotating shaft and a second range formed by the second seal ring are different.

A sealing assembly for a stem tube implemented in a retractable thruster system and the retractable thruster system therefor. The sealing assembly comprises an annular sealing housing. The annular sealing housing comprising a first sealing layer, arranged at an opening of the annular sealing housing, configured to prevent marine growth and fluid ingress, a second sealing layer, arranged after the first sealing layer, configured to form a water-tight seal against the stem tube, a third sealing layer, arranged after the second sealing layer, configured to accommodate relative movement of the stem tube, a fourth sealing layer, arranged between the first sealing layer and the second sealing layer, configured to be inflated for providing a temporary sealing barrier; and a drainage channel, arranged between the first sealing layer and the second sealing layer, configured to provide a dedicated path for removal of fluid ingress from the annular sealing housing.