Rock-bit seals with asymmetric contact profiles

A bit for drilling a borehole into earthen formations, the bit comprising:

• a bit body;
• a journal shaft extending from said bit body;
• a rolling cone cutter mounted on said journal shaft and being adapted to rotate about a cone axis;
• a seal gland between said shaft and said cone and comprising a first seal engaging surface on said shaft and a second seal engaging surface on said cone;
• an annular seal disposed in said gland, said annular seal comprising:
• a radially inner surface sealingly engaging said first seal engaging surface;
• a radially outer seal surface sealingly engaging said second seal engaging surface;
• and
• a seal footprint on one of said seal engaging surfaces, said footprint being defined by the portion of said seal contacting said one seal engaging surface, said footprint having a footprint length measured axially relative to said cone axis and being bisected by a footprint centerline that is perpendicular to said cone axis;
• wherein said seal creates a pressure profile on one of said seal engaging surface axially along said footprint, said pressure profile being asymmetric relative to said centerline.

A rotary cone rock-bit seal comprising:

• a first seal in contact with a rotating surface along a first footprint;
• a first centerline through the midpoint of the first footprint, wherein said first centerline divides said first seal into a drilling fluid side and a lubricant side;
• and
• a first contact pressure profile formed between said first seal and the rotating surface, wherein said first contact pressure profile is asymmetric about said first centerline.