Electrical switch for a braking fluid pressure fault alarm device

Abstract

An electric switch for use in a braking fluid pressure fault alarm device for a vehicular dual brake system, which device includes a body having a cylinder, a piston slidably inserted in the cylinder and receiving front and rear wheel braking fluid pressures for sliding movement from its inoperative position to its operative position in response to leakage of either of the braking fluid pressures, and an electric alarm circuit for generating an alarm signal when deenergized. The electric switch is engaged with the piston and is switched from its conductive condition to its non-conductive condition in response to sliding movement of the piston in order to deenergize the electric alarm circuit. This electric switch comprises a switch body having a stepped through bore, an annular support fixedly mounted in the switch body, an insulating terminal holder fixedly mounted in the switch body, a conductive plate disposed in the terminal holder, a terminal fixedly mounted in the terminal holder, a weak spring disposed in the terminal holder for biasing the plate into abutting engagement with the support, a plunger inserted in the switch body, and a spring interposed between the plunger and the support and compressed to be loaded at a preset level so as to bias the plunger apart from the plate. Thus, the plunger can be moved, in response to the sliding movement of the piston, from the inoperative position toward the plate to bring its insulating end portion into abutment engagement with the plate to thereby separate the plate from the support.