Hydraulic belt tensioner

摘要

A hydraulic belt tensioner operating on pressurized lubricating oil in an internal combustion engine. The tensioner includes a ratchet mechanism which locks the output member of the tensioner in a fixed position when the engine is not operating and which is disengaged when the engine is operating and the lubricating oil is pressurized. A seal is provided to prevent oil from escaping from the unit. The invention further includes slots formed in a plunger element of the tensioner which are effective to dissipate air which tends to become entrapped under the plunger when the engine is initially started.