To provide a chain tensioner easy to manage and capable of surely securing an air vent passage at the front end of a plunger.
A screw hole 19 is formed in the front end of the plunger 13 which is slidably inserted into a cylinder chamber 11 of a housing 10, a bolt 29 having a head portion 29a is screw-engaged with the screw hole 19 through the inside of an oil chamber 17 formed in the plunger 13, and a screw gap formed between screw-engaged portions thereof is served as the air vent passage 31. By incorporating a spring washer 30 between the head portion 29a of the bolt 29 and the closed end face of the oil chamber 17, a clearance a communicated with the air vent passage 31 is provided between the head portion 29a and the closed end face of the oil chamber 17. Then, the oil chamber 17 is communicated with the outside via the clearance a and the air vent passage 31. During pressure rise in the oil chamber 17, air mixed into operating oil in the oil chamber 17 is removed from the clearance a and the air vent passage 31 to the outside.
YAMADA MASAYOSHI
Naoya Kamata
Yaichiro Nakatani