Seal and groove set for disc brake actuator

Claim 1

In a disc brake having a housing defining a cylinder therewithin having a cylindrical surface, a circumferentially extending groove in said cylindrical surface; a seal having a substantially square cross section disposed in said groove, said groove having a first flank extending substantially perpendicular to the axis of said cylinder and a second flank extending obliquely to said axis of the cylinder, and a bottom flank interconnecting the first and second flanks having an annular ridge projecting radially inwardly toward the axis of said cylinder, said ridge being defined by the intersection of a first cone with a second cone, said first and second flanks intersecting said first and second cones respectively, the intersection of the first flank with the first cone defining a first circle, the intersection between the second cone and the second flank defining a second circle, the intersection of said cones at said ridge defining a third circle in a plane between the plane of the first and second circles, the plane of the third being nearer to the plane of the second circle than to the plane of the first circle.