Multiple feature master cylinder

Claim 1

In a fluid motor for use in a vehicle braking system having first and second hydraulic systems: a housing defining a bore therewithin; pressurizing means for developing fluid pressure within said first and second hydraulic systems, said pressurizing means having first and second pistons in said bore, said first piston being reciprocable with respect to said second piston; operator-actuated means operatively connected to said pressurizing means for energizing the same; said bore being divided by said pressurizing means into first and second hydraulic chambers; first and second outlet passage means in said housing for communicating pressurized fluid from said first and second hydraulic chambers, respectively, to front and rear brakes, respectively; pressure delaying means operatively connected to said first outlet passage means for regulating pressure transmission from said first hydraulic chamber to said front brakes; fluid pressure responsive pressure proportioning means operatively connected to said second outlet passage means for regulating pressure transmission from said second hydraulic chamber to said rear brakes; actuating means operatively connected to said pressure proportioning means for actuating the same to a predetermined open position; control means operatively connected to said actuating means and operative in response to a predetermined pressure loss in said first hydraulic pressure chamber for energizing said actuating means; warning means operatively connected to said control means and adapted to warn a vehicle operator of said pressure loss in said front brake, said warning means having a second bore within said second piston, said second piston including an extension, with a small diameter axial passage therethrough, one end of said second piston defining a shoulder at the juncture of said second bore and said passage; an external reduced diameter section on said second piston with at least one radial passage extending inwardly therethrough from said external reduced diameter section to said second bore; a gland threadedly engaging said second bore at the other end of said second piston having an internal stepped bore to present a larger and a smaller portion with a shoulder therebetween; wherein said control means includes, a third piston reciprocable in said second bore having a pair of opposed faces and a camming surface thereon, each of said first and second hydraulic systems being in communication with one of said faces whereby a predetermined pressure differential between said first and second hydraulic systems will shift said piston; a movable member disposed around said external reduced diameter section having at least one projection extending radially inwardly through said radial passage for engagement with said camming surface; and wherein said warning means includes electrical contact means abutting said movable member for converting motion of the latter to an electrical signal when a predetermined pressure differential exists between said first and second hydraulic chambers.