Abstract: A brake master cylinder reservoir diaphragm has a vent slit therein to operate as a vent valve to equalize air pressure when a pressure differential is impressed across the diaphragm as the brake fluid level in the reservoir changes. The vent slit has an omega or bell curve shape so that the movable valve member is the tongue-like part formed on the inner curvilinear part of the curved vent slit. The tongue valve member acts as a cantilever supported valve which bends at its base to open in either direction under a differential pressure acting on one side or the other of the diaphragm. The opening and closing action of the tongue valve member can be fine tuned by modifying the bending resistance of the base of that member. Such modifications can include a partial base slit extending only part way into the thickness of the base to form a groove in alignment with the straight ends of the omega slit and located between them.

Abstract: A reservoir diaphragm for a vehicle brake master cylinder fluid reservoir has a passage in communication with the atmosphere defined between the reservoir cover and diaphragm. The diaphragm has a slot receiving a projection from the cover to normally form a seal. The seal prevents pasage of air between the reservoir and the passageway when the reservoir substantially equals the atmospheric pressure. The diaphragm is movable with respect to the projection to open the seal when the pressure in the reservoir is less than the atmosphere thereby allowing air from the atmosphere to enter the reservoir.

Abstract: A dual chamber master cylinder has a center compensating valve for bypass compensation of the secondary pressurizing chamber, eliminating lip seal damage to the secondary piston seal that can occur when a bypass port is provided in the wall of the secondary pressurizing chamber.

Abstract: A clear ice maker has an improved stationary open-top water tray comprising a plastic frame with metal inserts in the tray side, end and bottom walls for containing a predetermined quantity of water. The tray receives a removable grid having a plurality of open-bottom, open-top ice mold cavities and flexible filler means between the cavities to displace substantially all of the water into the cavities when the grid is in the tray. The tray side and end metal inserts have heaters thereon which are activated prior to ice harvest to melt the ice bond between the grid and tray permitting release of the grid. The tray bottom wall metal insert has continuously energized heater means thereon and is formed to provide a raised area beneath each grid cavity, thereby preventing freezing through the bottom of the grid cavities.