Abstract: A fluid level indicating apparatus includes a piston and cylinder assembly which is located adjacent the surface of a body of fluid contained within fluid reservoir and includes openings to admit such fluid thereinto with the piston in one extreme axial position, and to vent air from the cylinder but restrict fluid flow therefrom during movement of the piston from the extreme axial position. The piston is connected by a link to a pivotally mounted level indicating plate which pivots in conjunction with pivotal movement of an actuator element (e.g. the hinged cap of the fluid reservoir closure) to a position indicating the level of fluid in the reservoir. The actuator element is releasably connected to the indicator plate in a manner to cooperate with the restriction of fluid flow from the cylinder upon piston movement to position the indicator plate at an appropriate level indicating position for any given fluid level within the indicating range of the apparatus.

Abstract: A low fluid level warning system (100) is adapted for use with a conventional oil circulation and low pressure warning system in an engine-driven vehicle. Oil from a crankcase reservoir (102) is pumped through an inlet conduit (110) to varius engine supply lines (116). A portion of the oil is also pumped into an enclosed chamber (124). A pressure sensor diaphragm (132) and switch contacts (130) sense the chamber pressure and illuminate a warning lamp (142) when the pressure is below a predetermined pressure. A drain conduit (160) extends from the bottom of the chamber at the bottom of the oil reservoir (102). A vent conduit (150) extends from the top of the chamber to a predetermined level in the reservoir (102). If the oil in the reservoir (102) is below the predetermined level, the chamber (124) drains completely when the engine is turned off. If the oil in the reservoir (102) is above the predetermined level, the chamber oil does not drain.