Brake failure indicator

Claim 1

In a brake system for a vehicle having two sets of brake, the improvement comprising a failure indicating means in response to a failure of either of the sets of brakes, said failure indicating means comprising a fluid pressure differential-responsive means normally being in a first position in response to pressures in both sets of brakes, said first position being approximately normal and being shifted to a second position in response to fluid pressure differential between the two sets of brakes, a displaceable means operatively connected to said pressure differential responsive means, and an electrically operable signal means associated with and controlled by said displaceable means, said electrically operable signal means comprising a normally active current circuit, a first switching member in the normally active current circuit operatively connected to said displaceable means, a second switching member responsive to the potential of the normally active current circuit, a signal device, and an operating current-supplying circuit for energizing the signal device, said second switching member forming the operating current-supplying circuit in order thereby to indicate occurrence of such pressure differential in the pressure differential responsive means; said displaceable means comprising a plunger having a conductor portion and an electrically insulating portion to form the first switching member, said conductor portion forming the normally active circuit while said insulating portion blocking the normally active current circuit in dependency upon displacement of the displaceable means.