Fluid level monitoring device

Claim 1

For use in combination with a closed bearing assembly comprising an axle, a bearing including an inner race fixedly mounted on said axle by a clamping cover plate and an outer race, a rotary member mounted upon said outer race for rotation upon said axle, and a closure cap sealingly secured to said rotary member to define a lubricating fluid containing chamber enclosing said bearing and said cover plate; apparatus for monitoring the level of lubricating fluid contained in said chamber comprising a capacitative measuring probe mounted at one end on said cover plate within said chamber and having a first capacitor plate disposed in spaced parallel opposed relationship to said cover plate; insulating spacer means carried by one of said plates and in engagement with the other of said plates for maintaining said plates spaced apart; and electric circuit means operatively connected to said first plate and said cover plate to constitute said cover plate as a second capacitor plate, the electrical capacitative reactance of said first and second plates being variable in accordance with changes in the level of lubricating fluid within said chamber.