Hydraulic belt tensioner.

摘要

A hydraulic belt tensioner (10) operating on pressurized lubricating oil in an internal combustion engine. The tensioner includes a ratchet mechanism (34) which locks the output member (18) 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 (28) is provided to prevent oil from escaping from the unit. The invention further includes slots (64) formed in a plunger element (25) of the tensioner which are effective to dissipate air which tends to become entrapped under the plunger when the engine is initially started. <IMAGE>