| 摘要 |
A detector for providing an audible indication of the vacuum condition for use in promoting the economic operation of a vehicle including a vacuum detector for detecting the magnitude of the vacuum condition in the manifold vacuum line of a vehicle to effect a switch closure which energizes an audible alarm. The vacuum detector comprises a piston reciprocally mounted within a piston chamber and movable responsive to changes in vacuum. A piston rod is arranged between combination switch and guide means for maintaining the axial alignment of the piston rod and for cooperating with conductive means arranged along the piston rod for establishing a conductive path for energizing the audible alarm when a predetermined vacuum condition is present. The contact design provides automatic silencing of the alarm when the engine is turned off or upon demand of engine power beyond a predetermined value. The small size allows for an out-of-sight dashboard mount without affecting operator recognition of the alarm. A piston controlled vacuum-operated audible alarm may be substituted for the battery operated unit.
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