Abstract: An hydraulic switch (10) for buoyingly controlling a secondary electrical switch (74) is disclosed. A float (68) is retained to move between a first position spaced apart from a vent opening (64) and a second position in sealing contact with vent opening (64). The electrical switch (74) changes state from an open condition to a closed condition as the float (68) approaches its second position.

Abstract: An hydraulic switch (10) and method for controlling the starting and stopping of a pump is disclosed. Switch (10) has an aperture (34) in the base (32) of a reservoir (28). Liquid enters aperture (34) thereby raising float (38) which operates switching mechanism (26) to start pump motor (20). As liquid is pumped passed impeller (22) along flow path A, some of the liquid is forced into conduit (36) leading to reservoir (28). The liquid flowing through conduit (36) keeps reservoir (28) filled. Consequently, float (38) remains in an elevated position keeping switch mechanism (26) on. Float (38) does not descend until liquid ceases to be pumped and stops flowing through conduit (36). Then, as liquid drains from reservoir (28) through aperture (34), float (38) drops thereby causing switching mechanism (26) to switch motor (20) off.