Annular shaft seal with cam portion on sealing lip

A method of installing an annular shaft seal over a first, larger diameter portion of a shaft and to seal against a second, smaller, diameter portion of the shaft, the seal comprising a mounting portion, a sealing lip portion, and a flexible channel-shaped portion interconnecting said mounting portion and said sealing lip portion, the sealing lip portion having a primary sealing lip and an annular cam portion disposed adjacent to and spaced axially from the primary sealing lip in a direction away from the mounting portion, the sealing lip portion being movable with respect to the mounting portion, from a sealing profile in which the primary sealing lip has a smaller diameter than the annular cam portion of the seal and is adapted for sealing contact with the second portion of the shaft, to a non-sealing profile in which the diameter of the primary sealing lip is larger than that of the annular cam portion of the seal, said method comprising the steps of moving the annular cam portion of the seal into engagement with the larger diameter portion of the shaft thereby distending the primary sealing lip to its larger diameter condition such that the primary sealing lip cannot contact either portion of the shaft when the seal is being installed on the shaft, whereby the primary sealing lip is maintained out of contact with the first portion of the shaft during installation, and further moving the annular cam portion of the seal in the same direction off the larger diameter portion of the shaft without reversal thereof automatically to return the sealing lip portion from non-sealing profile back to the sealing profile, whereby the primary sealing lip automatically moves into sealing contact with the second portion of the shaft after the annular cam portion of the seal has been moved over and beyond the first portion of the shaft to the second portion of the shaft.

An annular shaft seal to be moved over a first, larger diameter portion of a shaft and to seal against a second, smaller, diameter portion of the said shaft, comprising a mounting portion, a sealing lip portion, and a flexible channel-shaped portion interconnecting said mounting portion and said sealing lip portion, said sealing lip portion having a primary sealing lip and a secondary sealing lip disposed adjacent to and spaced axially from said primary sealing lip in a direction away from said mounting portion, said sealing lip portion being movable with respect to said mounting portion, from a sealing profile in which said primary sealing lip has a smaller diameter than said secondary sealing lip and is adapted to be in sealing contact with said second portion of said shaft, to a non-sealing profile in which the diameter of said primary sealing lip is larger than that of said secondary sealing lip, and in which said secondary sealing lip engages said larger diameter portion of the shaft thereby distending said primary sealing lip to its larger diameter condition such that said primary sealing lip cannot contact either portion of said shaft when said seal is being installed on said shaft, whereby said primary sealing lip is maintained out of contact with said first portion of said shaft during installation and after installation said sealing lip portion without reversal thereof automatically returns from non-sealing profile back to said sealing profile, whereby said primary sealing lip automatically moves into sealing contact with said second portion of said shaft after said secondary sealing lip has been moved over and beyond said first portion of said shaft to engage said second portion of said shaft.