Dynamic backup ring assembly

A sealing assembly comprising:

• a bulkhead housing defining a locating shoulder facing in a generally axial direction, said bulkhead housing having a portion thereof exposed to a first fluid having a first fluid pressure and having a portion thereof exposed to a second fluid having a second fluid pressure;
• a shaft defining an externally-oriented sealing surface of generally cylindrical form, at least part of said sealing surface being located at least partially within said bulkhead housing, and being relatively movable with respect to said bulkhead housing, said shaft having a portion thereof exposed to said first fluid and a portion thereof exposed to said second fluid;
• a retainer located radially outward of at least a portion of said shaft and surrounding at least part of said shaft sealing surface, and defining a retaining shoulder facing generally toward said locating shoulder of said bulkhead housing, said locating shoulder of said bulkhead housing facing in a generally axial direction toward said retaining shoulder, said retainer having a radially inward facing surface defining a gland bore of generally cylindrical form located in radially spaced relation to said shaft sealing surface and encircling said shaft sealing surface;
• a backup ring of generally circular form located between said retaining shoulder of said retainer and said locating shoulder of said bulkhead housing, said backup ring having a first ring end with at least a portion thereof facing said retaining shoulder and a second ring end with at least a portion thereof facing said locating shoulder, said first and second ring ends facing in generally opposite directions, said backup ring having a ring inner surface facing generally inward toward said shaft sealing surface and establishing a region of clearance therewith forming an extrusion gap between said ring inner surface and said sealing surface at said first ring end, and having a ring outer surface facing generally radially outward, said backup ring having radial thickness between said ring inner and outer surfaces, said ring inner and outer surfaces being exposed to said second fluid pressure;
• and
• a dynamic seal located at least partially within said gland bore of said retainer, said dynamic seal having a static sealing surface held in direct sealing contact with said gland bore and having a dynamic sealing surface in sealing contact with said shaft sealing surface, said dynamic seal having a first seal end exposed to said first fluid and a second seal end facing and in contact with said first ring end of said backup ring, said region of clearance located between said dynamic seal and said second ring end;
• said dynamic seal establishing first inner and outer sealing sites at said first ring end, said first outer sealing site located generally radially outward from said first inner sealing site, said first inner and outer sealing sites defining a first hydraulic area exposed to said first fluid pressure, said first fluid pressure acting over said first hydraulic area and producing a first axially oriented hydraulic force acting on said backup ring in a first hydraulic force direction acting generally toward said locating shoulder of said bulkhead housing.

A sealing assembly comprising:

• a bulkhead housing of annular form having a portion thereof exposed to a first fluid having a first fluid pressure and having a portion thereof exposed to a second fluid having a second fluid pressure that is less than said first fluid pressure, and having a locating shoulder facing in a generally axial direction;
• a shaft having a portion thereof exposed to said first fluid and a portion thereof exposed to said second fluid, said shaft defining a sealing surface of generally cylindrical form, at least part of said sealing surface being located at least partially within said bulkhead housing and being relatively movable with respect to said bulkhead housing;
• a retainer of annular form located radially outward of at least a portion of said shaft and encircling said shaft, said retainer defining a retaining shoulder facing generally toward said locating shoulder of said bulkhead housing and separated from said locating shoulder by an axial dimension, said retainer having a radially inward facing surface defining a gland bore of generally cylindrical form located in radially spaced relation to said shaft sealing surface and encircling at least part of said shaft sealing surface, said locating shoulder of said bulkhead housing facing generally toward said retaining shoulder;
• a dynamic seal of annular form located at least partially within said gland bore, said dynamic seal having a static sealing surface held in direct sealing contact with said gland bore of said retainer and having a dynamic sealing surface in sealing contact with said sealing surface of said shaft;
• a backup ring of generally circular form located between said retaining shoulder and said locating shoulder, and having a first ring end with at least a portion thereof facing and adjoining said retaining shoulder and a second ring end having at least a portion thereof facing and adjoining said locating shoulder, said first and second ring ends facing in generally opposite directions, said backup ring having a ring inner surface that is larger than, and facing generally radially inward toward, said shaft sealing surface and establishing an extrusion gap clearance and a bearing relationship therewith locating said backup ring radially, said backup ring having a ring outer surface facing generally radially outward, at least a portion of said ring outer surface located between said retaining shoulder and said locating shoulder, said backup ring having radial thickness between said ring inner surface and said ring outer surface, said first ring end located radially outward of and encircling said shaft sealing surface, at least part of said sealing surface located within said ring inner surface, no portion of said backup ring located between said dynamic seal and said retaining shoulder of said retainer;
• said dynamic seal having a first seal end exposed to said first fluid and a second seal end facing and in contact with said first ring end of said backup ring, said second seal end of said dynamic seal facing toward said locating shoulder, said second seal end of said dynamic seal being nearer to said locating shoulder than said first seal end of said dynamic seal;
• said dynamic seal establishing a first inner sealing site at said first ring end sealing said extrusion gap clearance between said ring inner surface and said shaft sealing surface, said dynamic seal exposed to said second fluid pressure at said extrusion gap clearance, and said dynamic seal establishing a first outer sealing site providing sealing between said first ring end and said retainer;
• an inner balancing seal in face sealing contact with said bulkhead housing and said second ring end of said backup ring establishing a second inner sealing site separated from said first inner sealing site by an axial distance;
• an outer balancing seal in face sealing contact with said bulkhead housing and said second ring end of said backup ring establishing a second outer sealing site separated from said first outer sealing site by an axial distance, said outer balancing seal encircling said shaft and located radially outward of and encircling said inner balancing seal;
• said first inner and outer sealing sites and said second inner and outer sealing sites each sealing said first fluid pressure from said second fluid pressure, said first outer sealing site located generally radially outward from said first inner sealing site and said second outer sealing site located generally radially outward from said second inner sealing site, said first inner sealing site and said first outer sealing site defining a first hydraulic area exposed to said first fluid pressure, said first fluid pressure acting over said first hydraulic area and producing a first axially-oriented hydraulic force acting on said backup ring in a first hydraulic force direction, and
• said second inner sealing site and said second outer sealing site defining a second hydraulic area exposed to said first fluid pressure, said first fluid pressure acting over said second hydraulic area and producing a second axially-oriented hydraulic force acting on said backup ring in a second hydraulic force direction that is opposite to said first hydraulic force direction, said bulkhead housing having a pressure passage passing through at least part of said bulkhead housing and having an open end located between said inner and outer balancing seals, said pressure passage communicating said first fluid pressure to said second hydraulic area.

A sealing assembly comprising:

• a bulkhead housing of annular form having an axial bore, said axial bore having first and second bore portions, said first bore portion defining an enlarged cavity bore having a locating shoulder facing in a generally axial direction and said second bore portion being the smallest portion of said axial bore, said smallest portion defining the innermost surface of said bulkhead housing;
• a shaft having an externally-oriented sealing surface of generally cylindrical form, at least part of said sealing surface located within said enlarged cavity bore of said bulkhead housing and being relatively movable with respect to said bulkhead housing;
• a retainer of annular form located radially outward of and around a portion of said shaft, said retainer defining a retaining shoulder facing said locating shoulder of said bulkhead housing, said retainer including a radially inward facing gland bore located around and in radially spaced relation to said shaft sealing surface, at least a part of said sealing surface being located inside said gland bore and at least a portion of said locating shoulder facing generally toward said retaining shoulder;
• a backup ring of generally cylindrical form received at least partially within said enlarged cavity bore and located between said retaining shoulder and said locating shoulder, said backup ring having first and second ring ends facing in opposite directions, at least a portion of said first ring end located radially outward of and encircling said shaft sealing surface and facing and adjoining said retaining shoulder and at least a portion of said second ring end facing said locating shoulder, said backup ring having a ring inner surface that is larger than, and facing generally radially inward toward, said shaft sealing surface and establishing an extrusion gap clearance and a bearing relationship therewith locating said backup ring radially, and said backup ring having a ring outer surface facing generally radially outward;
• a dynamic seal of annular form located at least partially within said gland bore of said retainer, said dynamic seal having a static sealing surface held in direct sealing contact with said gland bore of said retainer and having a dynamic sealing surface in sealing contact with said shaft sealing surface, said dynamic seal having first and second seal ends, said first seal end exposed to a first fluid having a first fluid pressure and said second seal end facing and in sealing contact with said first ring end of said backup ring, said second seal end of said dynamic seal facing toward said locating shoulder, said second seal end of said dynamic seal being nearer to said locating shoulder than said first seal end of said dynamic seal, no portion of said backup ring located between said dynamic seal and said retaining shoulder of said retainer;
• and
• at least part of said innermost surface of said bulkhead housing exposed to said second fluid and said second fluid pressure.

A sealing assembly comprising:

• a bulkhead housing of annular form having a locating shoulder facing in a generally axial direction and having an innermost surface of annular form and facing generally radially inward;
• a retainer of annular form having a retaining shoulder facing generally toward said locating shoulder of said bulkhead housing, said retainer having a radially inwardly facing annular surface defining a gland bore;
• a backup ring of generally circular form, at least a portion of said backup ring located between said retaining shoulder of said retainer and said locating shoulder of said bulkhead housing, said backup ring having a first ring end with at least a portion thereof facing said retaining shoulder and a second ring end with at least a portion thereof facing said locating shoulder, said first and second ring ends facing in generally opposite directions, said backup ring having a ring inner surface facing generally inward, and having a ring outer surface facing generally radially outward, said backup ring having radial thickness between said ring inner and outer surfaces;
• a shaft having a sealing surface of generally cylindrical form that is smaller than said ring inner surface, at least part of said sealing surface being located within said gland bore of said retainer, at least part of said sealing surface being located within said ring inner surface of said backup ring and establishing a region of clearance therewith, at least part of said sealing surface being located radially inward of and encircled by said first ring end of said backup ring, at least part of said shaft being located within said innermost surface of said bulkhead housing;
• a dynamic seal having an annular static sealing surface facing generally radially outward, an annular dynamic sealing surface facing generally radially inward, and first and second seal ends, said dynamic seal located at least partially within said gland bore of said retainer, said annular static sealing surface contacting said gland bore, said annular dynamic sealing surface contacting said sealing surface of said shaft, and said second seal end facing and contacting said first ring end of said backup ring;
• inner and outer balancing seals encircling said shaft and contacting said bulkhead housing and said second ring end of said backup ring, said outer balancing seal located radially outward of and encircling said inner balancing seal;
• and
• a pressure passage passing through at least part of said bulkhead housing and having an open end located between said inner and outer balancing seals.

A sealing assembly comprising:

• a bulkhead housing having a portion thereof exposed to a first fluid having a first fluid pressure and having a portion thereof exposed to a second fluid having a second fluid pressure, and having a locating shoulder facing in a generally axial direction;
• a shaft having a portion thereof exposed to said first fluid and a portion thereof exposed to said second fluid, said shaft defining a sealing surface of generally cylindrical form, at least part of said sealing surface located at least partially within said bulkhead housing and being relatively movable with respect to said bulkhead housing;
• a retainer of annular form located radially outward of at least a portion of said shaft and surrounding at least a portion of said shaft, said retainer defining a retaining shoulder facing generally toward said locating shoulder of said bulkhead housing;
• a backup ring of annular form having a first ring end with at least a portion thereof facing said retaining shoulder and a second ring end having at least a portion thereof facing said locating shoulder, said first and second ring ends facing in generally opposite directions, said backup ring having a ring inner surface facing generally inward toward said sealing surface and establishing a region of clearance therewith and a region of tangential contact therewith, and having a ring outer surface located radially outward of said ring inner surface and between said retaining shoulder and said locating shoulder and facing generally radially outward, said backup ring having radial thickness between said ring inner surface and said ring outer surface, said ring inner and outer surfaces exposed to said second fluid and said second fluid pressure, said region of tangential contact between said sealing surface of said shaft and said ring inner surface locating said backup ring laterally, said region of clearance forming an extrusion gap between said ring inner surface and said sealing surface of said shaft at said first ring end;
• said first ring end of said backup ring located directly radially outward of and surrounding said sealing surface;
• a dynamic seal contacting said sealing surface of said shaft and said first ring end of said backup ring and establishing a first inner sealing site sealing said extrusion gap between said ring inner surface and said sealing surface of said shaft, said dynamic seal or a face seal in sealing contact with said retainer and said backup ring establishing a first outer sealing site;
• an inner balancing seal in face sealing contact with said bulkhead housing and said second ring end of said backup ring establishing a second inner sealing site, said inner balancing seal spaced from said shaft by a radial distance, said inner balancing seal exposed to said first fluid pressure and said second fluid pressure;
• an outer balancing seal in face sealing contact with said bulkhead housing and said second ring end of said backup ring establishing a second outer sealing site, said outer balancing seal exposed to said first fluid pressure and said second fluid pressure, said outer balancing seal spaced from said shaft by a radial distance, said radial distance separating said outer balancing seal from said shaft being greater than said radial distance separating said inner balancing seal from said shaft;
• said first inner sealing site separated from said second inner sealing site by an axial distance, said first outer sealing site separated from said second outer sealing site by an axial distance, said second inner and outer sealing sites located radially outward of and encircling said shaft, said first inner and outer sealing sites and said second inner and outer sealing sites each sealing said first fluid from said second fluid, and sealing said first fluid pressure from said second fluid pressure, wherein:
• said first fluid pressure is greater than said second fluid pressure, said first outer sealing site located generally radially outward from said first inner sealing site and said second outer sealing site located generally radially outward from said second inner sealing site, said first inner sealing site and said first outer sealing site defining a first hydraulic area of annular form exposed to said first fluid pressure, said first fluid pressure acting over said first hydraulic area and producing a first axially-oriented hydraulic force acting on said backup ring in a first hydraulic force direction, and
• said second inner sealing site and said second outer sealing site defining a second hydraulic area of annular form exposed to said first fluid pressure, said first fluid pressure acting over said second hydraulic area and producing a second axially oriented hydraulic force acting on said backup ring in a second hydraulic force direction that is opposite to said first hydraulic force direction.

A sealing assembly comprising:

• a bulkhead housing having a portion thereof exposed to a first fluid having a first fluid pressure and having a portion thereof exposed to a second fluid having a second fluid pressure, and having a locating shoulder facing in a generally axial direction;
• a shaft having a portion thereof exposed to said first fluid and a portion thereof exposed to said second fluid, said shaft defining a sealing surface of generally cylindrical form, at least part of said sealing surface located at least partially within said bulkhead housing and relatively movable with respect to said bulkhead housing;
• a retainer of annular form located radially outward from at least a portion of said shaft and surrounding at least a portion of said shaft, said retainer defining a retaining shoulder facing generally toward said locating shoulder of said bulkhead housing and encircling a portion of said shaft;
• said locating shoulder facing generally toward said retaining shoulder and encircling a portion of said shaft;
• a backup ring of annular form having a first ring end with a portion thereof facing and adjoining said retaining shoulder and a second ring end having at least a portion thereof facing and adjoining said locating shoulder, said second ring end having an outer peripheral edge, said first and second ring ends facing in generally opposite directions, said backup ring having a ring inner surface and a ring outer surface located between said first and second ring ends, said ring inner surface facing generally inward toward said sealing surface of said shaft and establishing a region of clearance therewith and a region of tangential contact therewith, and said ring outer surface located radially outward of said ring inner surface and between said retaining shoulder and said locating shoulder, and facing generally radially outward, said backup ring having radial thickness between said ring inner surface and said ring outer surface, said ring inner and outer surfaces exposed to said second fluid and said second fluid pressure, none of said ring outer surface exposed to said first fluid pressure and none of said ring inner surface exposed to said first fluid pressure, said retainer capturing said backup ring axially relative to said bulkhead housing;
• said region of tangential contact between said sealing surface of said shaft and said ring inner surface locating said backup ring laterally;
• said region of clearance forming an extrusion gap between said ring inner surface and said sealing surface of said shaft at said first ring end;
• a dynamic seal establishing a first inner sealing site at said first ring end sealing said extrusion gap between said ring inner surface and said sealing surface of said shaft, a sealing element selected from a group consisting of said dynamic seal and a face seal establishing a first outer sealing site at said first ring end sealing between said first ring end and said retainer;
• an inner balancing seal in face sealing contact with said bulkhead housing and said second ring end of said backup ring establishing a second inner sealing site at said second ring end sealing between said second ring end and said bulkhead housing, and an outer balancing seal in face sealing contact with said bulkhead housing and said second ring end of said backup ring establishing a second outer sealing site at said second ring end sealing between said second ring end and said bulkhead housing;
• said outer balancing seal separated from said shaft by a radial distance and said inner balancing seal separated from said shaft by a radial distance, said radial distance separating said outer balancing seal from said shaft being greater than said radial distance separating said inner balancing seal from said shaft;
• said outer peripheral edge of said second ring end separated from said shaft by a radial distance, said radial distance separating said outer peripheral edge from said shaft being greater than said radial distance separating said outer balancing seal from said shaft;
• said first inner sealing site separated from said second inner sealing site by an axial distance, said first outer sealing site separated from said second outer sealing site by an axial distance, said second inner and outer sealing sites located radially outward of and encircling said shaft, said first inner and outer sealing sites and said second inner and outer sealing sites each sealing said first fluid from said second fluid, and sealing said first fluid pressure from said second fluid pressure;
• said first fluid pressure being greater than said second fluid pressure;
• said first outer sealing site located generally radially outward from said first inner sealing site and said second outer sealing site located generally radially outward from said second inner sealing site, said first inner sealing site and said first outer sealing site defining a first hydraulic area exposed to said first fluid pressure, said first fluid pressure acting over said first hydraulic area and producing a first axially-oriented hydraulic force acting on said backup ring in a first hydraulic force direction toward said locating shoulder, and
• said second inner sealing site and said second outer sealing site defining a second hydraulic area exposed to said first fluid pressure, said first fluid pressure acting over said second hydraulic area and producing a second axially-oriented hydraulic force acting on said backup ring in a second hydraulic force direction that is opposite to said first hydraulic force direction and toward said retaining shoulder.

A sealing assembly comprising:

• a bulkhead housing having a portion thereof exposed to a first fluid having a first fluid pressure and having a portion thereof exposed to a second fluid having a second fluid pressure, and having a locating shoulder facing in a generally axial direction;
• a shaft having a portion thereof exposed to said first fluid and a portion thereof exposed to said second fluid, said shaft defining a sealing surface of generally cylindrical form, at least part of said sealing surface located at least partially within said bulkhead housing and relatively movable with respect to said bulkhead housing;
• a retainer of annular form located radially outward from at least a portion of said shaft and surrounding at least a portion of said shaft, said retainer defining a retaining shoulder facing generally toward said locating shoulder of said bulkhead housing and encircling a portion of said shaft;
• said locating shoulder facing generally toward said retaining shoulder and encircling a portion of said shaft;
• a backup ring of annular form having a first ring end with a portion thereof facing and adjoining said retaining shoulder and a second ring end having at least a portion thereof facing and adjoining said locating shoulder, said second ring end having an outer peripheral edge, said first and second ring ends facing in generally opposite directions, said backup ring having a ring inner surface and a ring outer surface located between said first and second ring ends, said ring inner surface facing generally inward toward said sealing surface of said shaft and establishing a region of clearance therewith and a region of tangential contact therewith, and said ring outer surface located radially outward of said ring inner surface and between said retaining shoulder and said locating shoulder, and facing generally radially outward, said backup ring having radial thickness between said ring inner surface and said ring outer surface, said ring inner and outer surfaces exposed to said second fluid and said second fluid pressure, none of said ring outer surface exposed to said first fluid pressure and none of said ring inner surface exposed to said first fluid pressure, said retainer capturing said backup ring axially relative to said bulkhead housing;
• said region of tangential contact between said sealing surface of said shaft and said ring inner surface locating said backup ring laterally;
• said region of clearance forming an extrusion gap between said ring inner surface and said sealing surface of said shaft at said first ring end;
• a dynamic seal having a first seal end exposed to said first fluid and a second seal end facing toward said first ring end of said backup ring, said dynamic seal establishing sealing between said backup ring and said sealing surface of said shaft, thereby preventing said first fluid from escaping through said region of clearance between said ring inner surface and said sealing surface of said shaft;
• a sealing element selected from a group consisting of said dynamic seal and a face seal contacting said retainer and said backup ring and establishing sealing between said first ring end and said retainer and preventing said first fluid from escaping between said first ring end and said retainer;
• an inner balancing seal in face sealing contact with said bulkhead housing and said second ring end of said backup ring establishing sealing between said second ring end and said bulkhead housing, and an outer balancing seal in face sealing contact with said bulkhead housing and said second ring end of said backup ring establishing sealing between said second ring end and said bulkhead housing, said inner balancing seal exposed to said first and second fluids and said outer balancing seal exposed to said first and second fluids, some of said first fluid located within an annular sealed region located between said inner and outer balancing seals and located between said locating shoulder and said second ring end, said first fluid within said annular sealed region contacting an annular portion of said second ring end;
• said outer balancing seal separated from said shaft by a radial distance and said inner balancing seal separated from said shaft by a radial distance, said radial distance separating said outer balancing seal from said shaft being greater than said radial distance separating said inner balancing seal from said shaft;
• said outer peripheral edge of said second ring end separated from said shaft by a radial distance, said radial distance separating said outer peripheral edge from said shaft being greater than said radial distance separating said outer balancing seal from said shaft;
• said dynamic seal separated from said inner balancing seal by an axial distance, said dynamic seal separated from said outer balancing seal by an axial distance, said inner and outer balancing seals each sealing said first fluid from said second fluid, and said inner and outer balancing seals each sealing said first fluid pressure from said second fluid pressure;
• said first fluid pressure being greater than said second fluid pressure;
• said first fluid pressure acting on said dynamic seal and producing a first axially-oriented hydraulic force acting on said backup ring in a first hydraulic force direction toward said locating shoulder, and said first fluid pressure acting on said annular portion of said second ring end of said backup ring and producing a second axially-oriented hydraulic force acting on said backup ring in a second hydraulic force direction that is opposite to said first hydraulic force direction and toward said retaining shoulder.

A sealing assembly comprising:

• a bulkhead housing of annular form having a portion thereof exposed to a first fluid pressure and having a portion thereof exposed to a second fluid pressure, and having a locating shoulder facing in a generally axial direction, and having an innermost surface of annular form and facing generally radially inward, said first fluid pressure being greater than said second fluid pressure;
• a shaft having a portion thereof exposed to said first fluid pressure and a portion thereof exposed to said second fluid pressure, said shaft being relatively movable with respect to said bulkhead housing and defining an externally oriented surface of generally cylindrical form, at least a portion of said shaft being located within and encircled by at least a portion of said bulkhead housing;
• a retainer of annular form located radially outward from at least a portion of said shaft and encircling a portion of said shaft, said retainer defining a retaining shoulder facing generally toward said locating shoulder of said bulkhead housing and encircling a portion of said shaft, said retaining shoulder being axially spaced from said locating shoulder, at least a portion of said retainer being exposed to said first fluid pressure;
• said locating shoulder of said bulkhead housing facing generally toward said retaining shoulder of said retainer and encircling a portion of said shaft;
• an annular ring having a first ring end with at least a portion thereof facing and adjoining said retaining shoulder and a second ring end facing away from said retaining shoulder and having at least a portion thereof facing and adjoining said locating shoulder, said annular ring being captured axially relative to said bulkhead housing by said retainer, said second ring end having an outer peripheral edge, said first and second ring ends facing in generally opposite directions, said annular ring having a ring inner surface and a ring outer surface, said ring inner and outer surfaces encircling at least a portion of said externally oriented surface of said shaft, at least part of said externally oriented surface of said shaft being located within said ring inner surface, said ring inner surface being larger than and facing generally inward toward said externally oriented surface of said shaft and establishing a region of clearance therewith and a region of tangential contact therewith, at least part of said ring outer surface located radially outward of said ring inner surface and located in intermediate location to said retaining shoulder and said locating shoulder, and facing generally radially outward away from said externally oriented surface of said shaft, said annular ring having radial thickness between said ring inner surface and said ring outer surface, at least part of said annular ring being located inside a component selected from a group consisting of said retainer and said bulkhead housing, said ring inner surface of said annular ring being closer to said externally oriented surface of said shaft compared to said innermost surface of said bulkhead housing;
• said retaining shoulder of said retainer is separated from said locating shoulder of said bulkhead housing by an axial dimension and said annular ring having an axial length between said first and second ring ends, said axial dimension separating said locating shoulder from said retaining shoulder being greater than said axial length between said first and second ring ends,
• said region of tangential contact between said externally oriented surface of said shaft and said ring inner surface locating said annular ring laterally and at least a portion of said region of tangential contact being located in intermediate relation to said first and second ring ends, and at least a portion of said ring inner surface being located in intermediate relation to said first and second ring ends, no portion of said annular ring being located directly between said first ring end and said retaining shoulder of said retainer;
• a sealing element encircling a portion of said shaft and contacting said retainer and said annular ring and establishing sealing between said first ring end and said retainer, said sealing element being exposed to said first fluid pressure and preventing said first fluid pressure from escaping between said first ring end and said retainer, no portion of said annular ring being located between said sealing element and said retaining shoulder of said retainer;
• an inner balancing seal encircling a portion of said shaft and contacting and sealing between said bulkhead housing and said annular ring and preventing the loss of said first fluid pressure between said second ring end and said locating shoulder, and an outer balancing seal encircling a portion of said shaft and contacting said bulkhead housing and said annular ring and preventing the loss of said first fluid pressure between said second ring end and said locating shoulder, at least a portion of said second ring end and at least a portion of said ring outer surface being located farther from said shaft than said outer balancing seal, said inner balancing seal exposed to and contacted by said first and second fluids and said outer balancing seal exposed to said first fluid pressure, some of said first fluid pressure located within an annular sealed region located between said inner and outer balancing seals and located between said locating shoulder and said second ring end, said first fluid pressure within said annular sealed region acting on an annular portion of said second ring end;
• a pressure passage formed in said annular ring or said bulkhead housing containing said first fluid pressure and communicating said first fluid pressure to said annular sealed region, said pressure passage having an open end opening into said annular sealed region, at least part of said open end being located radially outward of said inner balancing seal and at least part of said open end being located radially inward of said outer balancing seal, said open end being separated from said shaft by a radial distance,
• said inner balancing seal being and located at least partially within and contacting an inner annular groove formed in one of said bulkhead housing and said annular ring, said outer balancing seal being located at least partially within and contacting an outer annular groove formed in one of said bulkhead housing and said annular ring,
• said outer annular groove being separated from shaft by a radial distance and said inner annular groove being separated from said shaft by a radial distance, said radial distance separating said outer annular groove from said shaft being greater than said radial distance separating said inner annular groove from said shaft,
• said outer balancing seal separated from said shaft by a radial distance and said inner balancing seal separated from said shaft by a radial distance, said radial distance separating said outer balancing seal from said shaft being greater than said radial distance separating said inner balancing seal from said shaft, said outer balancing seal being farther from said shaft than said inner balancing seal;
• said radial distance separating said open end from said shaft being greater than said radial distance separating said inner balancing seal from said shaft and being less than said radial distance separating said outer balancing seal from said shaft,
• said outer peripheral edge of said second ring end separated from said shaft by a radial distance, said radial distance separating said outer peripheral edge from said shaft being greater than said radial distance separating said outer balancing seal from said shaft and greater than said radial distance separating said outer annular groove from said shaft, said outer peripheral edge of said second ring end being located generally radially outward of said outer annular groove and generally radially outward of said outer balancing seal and being located farther from said shaft compared to said inner and outer balancing seals;
• said inner balancing seal located between and exposed to said first and second fluid pressures and partitioning said first fluid pressure from said second fluid pressure, and said outer balancing seal being exposed to and retaining said first fluid pressure;
• said first fluid pressure acting on said annular ring and producing a first axially-oriented hydraulic force acting on said annular ring in a first hydraulic force direction toward said locating shoulder, and said first fluid pressure acting on said annular sealed region of said second ring end of said annular ring and producing a second axially-oriented hydraulic force acting on said annular ring in a second hydraulic force direction that is opposite to said first hydraulic force direction and toward said retaining shoulder;
• said innermost surface of said bulkhead housing being the surface of said bulkhead housing located nearest to said shaft, said innermost surface of said bulkhead housing being exposed to said second fluid pressure,
• a portion of said second ring end radially inward of said inner balancing seal exposed to said second fluid pressure, a portion of said second ring end radially outward of said inner balancing seal and radially inward of said outer balancing seal exposed to said first fluid pressure,
• a portion of said bulkhead housing radially inward of said inner balancing seal exposed to said second fluid pressure, a portion of said bulkhead housing radially outward of said inner balancing seal and radially inward of said outer balancing seal exposed to said first fluid pressure,
• no portion of said bulkhead housing being located directly between said first ring end of said annular ring and said retaining shoulder, and no portion of said bulkhead housing being located directly between said second ring end of said annular ring and said locating shoulder of said bulkhead housing.