Abstract: A sealing ring for sealing between opposed surfaces of a bore and a rod extending axially in the bore has a recess, preferably in the form of a narrow axially-opening annular slot, behind one or mote sealing lips thereof. The dimensions of the recess are selected so that its opposed radial faces are squeezed together in the installed condition of the seal, giving a positive radial squeeze of seal material behind the sealing lips. The positive squeeze enables a stronger sealing force to be achieved, while the presence of the recess reduces overall radial compression force and hence avoids excessive friction.

Abstract: Buffer seal rings are described, and gland seals using them. The ring seats in an axially oversize housing groove in the gland bore in order to protect a main rod seal from pressure shocks. To avoid the possibly damaging effects of pressure trapping between the rod seal and buffer seal, the buffer seal has a sealing face on the rod seal side which includes a recessed driving surface e.g. an annular channel, lying inside an annular sealing portion. The driving surface communicates with the fluid in the bore through communication recesses, e.g. slots in an inner support rib, so that excess pressure on that side can drive the ring axially out of sealing and allow the pressure to be relieved through axially-extending pressure release grooves around the edge and oppostie face of the ring.