Sealed bearing and self-venting seal therefor

A circular seal comprising:

• a seal case having a pair of generally rigid spaced apart walls that are fixed in position with respect to each other and are configured and arranged such that an annular chamber exists between the walls;
• means for providing communication between the chamber and the region beyond one of the walls;
• a first annular seal lip mounted on one of the walls and adapted to contact a wear surface that is movable relative to the seal;
• and a second annular seal lip mounted on one of the walls and extended toward and normally contacting the other of the walls along a generally circular area that is generally concentric with respect to the first seal lip without moving circumferentially with respect to either of the walls, so as to provide a static seal along the other wall and thereby close the chamber, the second seal lip being sufficiently flexible wherein said second lip will move away from the other wall in response to an increase in pressure of predetermined magnitude within the chamber, whereby the pressure within the chamber and the region in communication with it does not exceed a predetermined magnitude.

In a bearing assembly including an outer race, an inner race, rolling elements arranged in a row between the two races so that the one race may turn easily with respect to the other race, a bore at the end of the outer race, and a wear surface at the end of the inner race, an improved seal for isolating the region occupied by the rolling elements, said seal comprising:

• a generally rigid seal case having an axial wall that fits into the bore at the end of the outer race and inner and outer radial walls extended generally radially inwardly from the axial wall, the inner radial wall being presented toward the isolated region and the outer radial wall being presented away from the isolated region, the radial walls being spaced apart so that an annular chamber exists between them, with the chamber being in communication with the isolated region of the bearing;
• a first annular seal element mounted on the inner radial wall and extended to and contacting the wear surface;
• and a second annular seal lip mounted on one of the radial walls and extended toward and normally contacting the other radial wall along a generally circular area that is concentric with respect to the first seal lip so as to provide a static seal along the other wall and thereby close the chamber, the second seal lip being capable of flexing when the pressure within the chamber and the isolated region of the bearing reaches a predetermined magnitude so that the pressure within the chamber is relieved, whereby the pressure within the isolated region does not exceed the predetermined magnitude.