GB488509A - Improvements in tensioning devices for transmission chains and the like - Google Patents

Abstract

488,509. Tensioning belts and chains. WELLER, J. March 15, 1937, Nos. 7472, 15003, and 35155. [Class 80 (i)] A sprocket wheel or pulley for taking up slack in a chain or belt is freely rotatable on a bearing A which is mounted eccentrically on a supporting pin B and is urged towards the path of the chain or belt by a loading spring which is mounted directly between pivoted points within or upon the face of the bearing in such a manner that an approximately constant force is exerted by the sprocket or pulley throughout its range of movement. The loading spring may be a bow spring or a coil spring operating in either tension or compression. In one form the loading spring is a compression spring K located in cups L, M pivoted within the bearing at O and N, the pivot N being a pin fixed to an external collar E on the supporting pin B. As the spring extends and the bearing rotates the distance of the line of action of the spring from the supporting pin increases so that although the force exerted by the spring decreases, the turning moment on the bearing is approximately constant. In a modified construction, the loading spring is mounted in a recess at one side of the bearing ; or two springs may be mounted one on each side of the bearing. In another modification, Fig. 8, the cups may be replaced by a U-shaped member L within which slides a flat T-shaped member M. The movement of the bearing in either direction is limited by the pivot pin contacting with the sides of openings P therein. To prevent the bearing rotating away from the path of the chain one or more pawls may be mounted on the bearing and engage a ratchet or ratchets F formed on the collar or collars E of the supporting pin, each pawl being held in engagement with the ratchet by a low spring J pressing against a flat H on the pawl spindle. Alternatively, a ratchet rotatable with the bearing may be engaged by pawls mounted on a boss of the chain case and embraced by a spring ring engaging flats on the pawl spindles. According to the second Provisional Specification, when a tension spring is used on the face of the bearing one of its pivots may be located outside the periphery of the bearing being carried on an extension thereof. This Specification also states that a pawl spindle may be utilized as one of the spring pivots.