Instrument for indicating liquid levels

Claim 1

An instrument for indicating the level of liquid contained in an above-ground storage reservoir having a lower end, said instrument comprising: support means; a casing, mounted on said support means, having a bellows so disposed therein as to provide a space between the casing and the bellows, said bellows being expandable and collapsible in a linear direction; an inlet conduit extending into the casing at a first location so as to be in communication with said space for connecting said liquid from the lower end of said reservoir with said space to effect increments of collapse of said bellows in the presence of liquid pressure; means in said bellows constantly biasing said bellows for expansive movement in opposition to said liquid pressure thereon; a first shaft fixedly connected with said bellows and movable therewith; a second shaft having an end journalled for rotation on said support means and an indicator arm fixedly connected, intermediate its ends, on said second shaft for rotation therewith; indicia mounted on said support means in juxtaposition relative to said indicator arm and positioned to be swept thereby; a fulcrum shaft having an end fixedly connected on said support means; a first lever having a pair of opposed ends with one of its said ends being pivotally connected on said fulcrum shaft; a segment gear carried on the other end of said first lever; a pinion on said second shaft meshing with said segment gear; means connecting said first lever with said first shaft; a one-way check valve biased to its closed position; and conduit means, extending from the casing at a second location that is above said first location so as to be in communication with said space, connecting said space with said one-way check valve.