MECHANICAL SEAL

PURPOSE:To always assure sealing pressure on a shaft-sealing and face, by providing an auxiliary spring to apply the sealing pressure to a seal ring when counter pressure acts to a main spring through an O-ring. CONSTITUTION:A seal ring retainer 29 is provided with an inner groove 33 extending on one end and fitted with an inner ring 31, so that an O-ring 34 for sealing a shaft is inserted. A seal ring 35, which rotates on a fixed ring 24, is provided on the other end of the retainer 29. An engaging pin 36 projecting from a drive collar 28 is inerted into the engaging hole 37 of the seal ring retainer 29 so that the collar and the retainer can together slide in the axial direction and rotate in the circumferential direction. An auxiliary spring 39, whose resilient force is set equal to or lower than a main spring 32, is inserted into the holding hole 38 of the retainer 29 to always elastically urge the retainer toward the fixed ring 24.