Valve stem seals.

摘要: A valve stem seal comprises an elastomeric moulding adapted to lip against a and, at its sealing region, is helically ribbed on stem-adjacent surface define lubricant control passages. The also provides downstream of seal, in terms flow, collar contact the provide both compensation for lateral loading resulting from rocker action and secondary seal. may be integral with but it preferred that constituted by plastics ring, preferably not exclusively formed PTFE, held within non-bonded relationship.