| 摘要 |
<p>The object is to provide a chain tensioner of which the plunger can be kept in a retracted position and of which the housing is small in size and light in weight.</p><p>The chain tensioner comprises a cylindrical housing 1, a plunger 3 slidably mounted in the housing 1, and a return spring 7 mounted in the housing 1 and biasing the plunger 3 outwardly of the housing 1. The housing 1 is formed with a stepped setting groove 12 in a radially inner surface thereof near its open end. The setting groove 12 comprises a deep portion 12a and a shallow portion 12b. A radially elastically deformable setting ring 13 having two separate circumferential ends and received in the setting groove 12 in a radially compressed state. The setting ring 13 includes a pair of tabs 13a provided at the two separate circumferential ends, respectively, and received in a cutout 14 formed in the housing 1 at the open end. The setting ring 13 can be radially compressed by operating the tabs 13a. The plunger 3 can be retained in a position where the plunger 3 is pushed in the housing 1 by engaging the setting ring 13 in an engaging groove 15 formed in a radially outer surface of the plunger 3 near its front end, while keeping the setting ring 13 in elastic contact with a bottom of the shallow portion 12b of the setting groove 12. Thus, the tensioner can be easily mounted in position. The tabs 13a of the setting ring 13 extend in directions that intersect a plane perpendicular to a central axis of the setting ring 13. This makes it possible to reduce the wall thickness of the housing 1 and thus its size and weight.
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