Sealed bearing and self-venting seal therefor

Abstract

A bearing having an outer race provided with end bores, inner races provided with wear surfaces located within the end bores, and rolling elements arranged in two rows between the races, is closed at its ends by seals which prevent excessive pressure from developing within the bearing during operation or relubrication. Each seal includes a metal case having an axial wall and pair of spaced apart radial walls. The axial wall is pressed into one of the end bores of the outer race, whereas the radial walls form a chamber that communicates with the interior of the bearing through apertures in the inner radial wall. An elastomeric seal element is bonded to the inner radial wall and it includes a primary seal lip that extends beyond the axial wall of the case and contacts the wear surface axially inwardly from the radial wall, a secondary lip that contacts the wear surface in the region of the inner radial wall, and a vent lip that extends toward and normally contacts the outer radial wall so as to close the end of the chamber that is between the two radial walls. However, when the pressure within the chamber, and the bearing as well, increases to a predetermined magnitude, which is considerably less than the pressure at which the seal will be dislodged or the primary lip damaged, the vent lip will flex and relieve the pressure. Thus, the pressure within the bearing never exceeds the predetermined magnitude.