Abstract: Each of the pistons has a metallic, ceramic or high glass nylon plastic core insert with glass-filled nylon plastic molded around it to form the finished piston. The finished piston is ready to use as it comes from the mold. The core insert is designed to maintain a substantially uniform plastic wall thickness and provide support lands behind the high pressure lands of the piston. The core insert also incorporates undercuts or grooves to prevent the core from being pushed out of the piston assembly. The grooves also allow the plastic to bond to the core. The core insert transmits the direct axial force of the push rod, and the plastic outer case supports the seals.

Abstract: A rod and guide assembly which permits free axial rod movement and does not allow the rod to rotate excessively in the rod guide. The rod is a cast member having a main body of circular cross section and a key integrally formed therewith and extending from and axially along one side of the main body. The parting line plane of the rod passes through the rod axis and substantially at right angles to a plane passing through the center of the key and the rod main body axis. The guide member has a guide aperture through which the rod extends. The aperture is defined by circumferentially spaced axially extending wall sections having circumferentially spaced and radially extending recesses therebetween. Two circumferentially opposite recesses have an axially extending plane passing therethrough and through the aperture axis. This plane is perpendicular to a similarly extending plane passing through at least one other such recess.

Abstract: A hydraulic brake fluid level sensing system having a switch housing above a diaphragm which sealingly encloses a fluid reservoir. A float rod guide extends through the diaphragm and a float rod extends through the rod guide and into the switch housing. A float vertically positions the float rod in accordance with brake fluid level. A switch element is positioned by the float rod to bridge a pair of contacts when the fluid level decreases to a specified level. A slot is provided in the rod guide to provide a vent to the fluid reservoir when the diaphragm is moved down the rod guide by differential pressure thereacross resulting from brake fluid loss.