Apparatus for sealing between a shaft and housing with multiple land members and seal members

Claim 1

A shaft sealing system for use in apparatus including a shaft and a housing, through which the shaft extends, and wherein relative rotation occurs between the shaft and housing, said system comprising: first, second, third, fourth, fifth and sixth annular land members located on the shaft and projecting toward the housing; an annular spacer member positioned on the shaft between each of said first and second, third and fourth, and fifth and sixth land members; an annular spacing member located on the shaft between said second and third land members and between said fourth and fifth land members; first, second, and third generally annular seal members frictionally engaging the housing and respectively located between and in close proximity to said first and second, third and fourth, and fifth and sixth land members, respectively; and, means for providing fluid at one pre-selected pressure between said second and third land members and at a different pre-selected pressure between said fourth and fifth land members whereby the pressure differential across each seal member can be controlled.