Air-operated conveyor belt tensioning apparatus

An apparatus for tensioning a conveyor belt used in a conveyor belt scale system for transporting construction material such as rock and soil over a considerable distance at construction sites, the conveyor belt including an upper run portion for support of the construction material thereon, and a lower return run portion, the conveyor system further including a conveyor frame for supporting the upper run, the apparatus comprising:

• an open center tensioning frame assembly having infeed and outfeed end members and two connecting side members, wherein the end members and side members define a tensioning frame plane;
• means for mounting the tensioning frame assembly to the conveyor frame beneath the upper run portion of the belt in such a manner that said tensioning frame assembly can move about said mounting means such that as the infeed end of the tensioning frame assembly moves downwardly, the outfeed end thereof moves upwardly and vice versa;
• a first set of rollers mounted on the tensioning frame assembly so that they extend substantially across said tensioning frame assembly in the vicinity of the infeed and outfeed ends thereof, a first roller being positioned on a first mounting assembly which extends above the tensioning frame plane at the infeed end of the tensioning frame assembly, while a second roller is positioned on a second mounting assembly which extends below the tensioning frame plane at the outfeed end of the tensioning frame assembly, wherein the return run portion of the belt extends over the first roller, through the open center area of the tensioning frame assembly and under the second roller;
• and
• fluid actuated means connected to said tensioning frame assembly for maintaining precise control over the position of the tensioning frame assembly and hence precise control over the tension on the belt.