Warning device for brake systems and the like

Claim 1

A failure warning device for indicating a pressure differential between first and second fluid-pressurized systems, said device comprising: a housing; a cylindrically stepped bore within said housing; said bore having a first portion at one end thereof, a second intermediate portion larger than said first portion, and a third portion larger than said second portion at the opposite end of said bore, said first portion in fluid communication with said first fluid-pressurized system, said third bore portion in fluid communication with said second fluidpressurized system; a cylindrically stepped shuttle-piston within said bore, said piston having a large diameter portion disposed within said first bore portion and a smaller diameter portion within said third bore portion; a reset sleeve member receiving said small diameter piston portion and disposed within said third bore portion, said sleeve having an axial end positioned at the juncture of said second and third bore portions and at the juncture of said first and second piston portions when said fluid-pressurized systems are at approximately equal pressures to maintain said piston in a centered position within said bore; a first seal between said large diameter piston portion and said first bore portion preventing fluid communication from said first bore portion to said second bore portion independent of the axial position of said piston within said bore; a second seal within said third bore portion at the opposite axial end of said sleeve preventing fluid communication between said third bore portion and said second bore portion independent of the axial position of said piston within said bore; signal means associated with said piston and extending within said second bore sensing axial displacement of said piston within said bore to actuate a signal device in response to said axial displacement; said device further includes stop means limiting displacement of said piston in one axial direction within said bore when failure occurs in said second brake system; said stop means including an inlet port in said housing in fluid communication with said second system and axially aligned with and at the end of said third bore portion, an outlet port in said housing angularly disposed from said inlet port and a cylindrically-hollowed, open-ended retainer disposed within said third bore between said inlet and outlet ports; and said retainer having a base surfacE with an opening therethrough at one of its axial end faces abutting a stop defined by said inlet port, said smaller diameter piston always extending within said retainer with the retainer length such that the interior of said base surface is in engagement with the end of said smaller diameter piston portion when said piston is axially shifted in one direction upon failure in pressure of said second system, and a plurality of flutes formed about the exterior of said retainer for supporting said retainer in said bore while defining a plurality of longitudinally-extending slots permitting unimpeded fluid communication between said outlet port and said third bore, the other axial end face defined as an annulus and effective to maintain said first seal undeformed about said smaller diameter piston portion and within said third bore upon failure in pressure of said second system.