Shaft seal ring

Claim 1

In a shaft seal ring having a resilient sealing lip provided with a contact face oriented at an inclined angle with respect to the seal ring axis; the contact face including a sealing edge for circumferentially engaging the surface of a shaft on which the shaft seal ring is mounted; the sealing edge determining a liquid side and an air side for the shaft seal ring; the contact face being provided with a plurality of circumferentially disposed ribs oriented at alternatingly opposite inclination with respect to the sealing edge; any adjoining, oppositely inclined two ribs constituting first and second ribs that meet at a point of intersection on the sealing edge and form first rib pairs; said first rib pairs being disposed at the air side; the improvement comprising a second rib pair provided in the area bounded by each said first rib pair; each second rib pair being formed by a third rib and fourth rib terminating on the first and second rib, respectively, of the associated first rib pair at a distance from their said point of intersection; said third rib having a reverse direction of inclination with respect to the first rib on which it terminates and said fourth rib having a reverse direction of inclination with respect to the second rib on which it terminates; the area bounded by said sealing edge and located externally of the areas bounded by each said first rib pair being rib-free and thereby reduce the total contact area of the ribs of said seal in the area bounded by the sealing edge.