| 摘要 |
<p>A chain-tensioning device comprises at least one main chain-tensioning sprocket wheel on which a chain engages, a main spring that urges a shaft of the main chain-tensioning sprocket wheel in a direction of tensioning of the chain, and an auxiliary cam element that engages a cam-follower element operatively connected to the shaft of the main chain-tensioning sprocket wheel so as to tend to push this shaft in the tensioning direction under the action of auxiliary elastic means. The auxiliary cam element automatically recovers any play that is generated owing to wear of the chain and prevents a movement of the chain-tensioning sprocket wheel in a direction opposite to the tensioning direction. In a variant, two main chain-tensioning sprocket wheels are provided, each having a respective auxiliary cam element. The two auxiliary cam elements may form part of a single pivoted lever.</p> |
