TENSIONER

摘要

Provided is a tensioner with which structural simplification, improved locking teeth strength, elimination of backlash, reduction of the number of components and cost, and design flexibility can be achieved. The tensioner has a cylindrical member (1) having multiple locking teeth (1b), one or multiple locking pieces (2) having locking teeth (2a) to be engaged with the locking teeth (1b), and a locking piece receiving part to receive the aforementioned locking pieces. The tensioner is provided with a shaft member (3) disposed inside the cylindrical member, and either the cylindrical member or the shaft member constitutes a thrust member that can be driven forward and backward by a biasing force. A ratchet mechanism is provided to allow the thrust member to move forward by the locking pieces riding over the locking teeth of the cylindrical member as they move in a reduced-diameter direction and to constrain retraction of the thrust member by the locking pieces engaging with the locking teeth of the cylindrical member as they move in an increased-diameter direction. The locking teeth are all thread-like teeth having a lead angle, and the dimensions or specifications of the respective components of equation 3 are set so as to establish the relationship in equation 3. (3)