Cylinder piston rod unit

A cylinder piston rod unit comprising a cylinder member (4) having an axis (X) and two ends, a piston rod guiding and sealing unit (C) adjacent at least one of said two ends and a piston rod member (2) axially extending through said piston rod guiding and sealing unit (C), said piston rod guiding and sealing unit (C) comprising at least one sealing ring member (5), said sealing ring member (5) being axially fastened with respect to said one end of said cylinder member (4), said sealing ring member (5) having a substantially axially extending sealing sleeve portion(7) of elastomeric material surrounding said piston rod member (2), said sealing sleeve portion (7) having a radially inner sealing face (7a) sealingly engaging an external cylindrical face (2a) of said piston rod member (2), a closed sealing pressure application ring (11) being mounted on said sealing sleeve portion (7) radially outwards of said radially inner sealing face (7a), said sealing pressure application ring (11) being free for radial movement, said sealing pressure application ring (11) being subject to a circumferential tensional force at least in the lower part of a range of operational temperatures of said sealing sleeve portion (7), said circumferential tensional force maintaining a radial sealing pressure between said radially inner sealing face (7a) of said sealing sleeve portion (7) and said external cylindrical face (2a) of said piston rod member (2), said sealing pressure application ring (11) being substantially non-extensible by said circumferential tensional force.