Patent ID: 8312894

Claim:
A valve comprising: a pneumatically discrete housing having first and second parallel planar ports with different cross sectional areas, said ports being aligned on an axis perpendicular thereto; a bearing mounted inside said housing between said ports; an assembly comprising: a shaft aligned on said axis, extending through said ports and mounted for lengthwise reciprocation in said bearing; and first and second parallel plates mounted on said shaft with said bearing therebetween, said plates being spaced at a distance less than a distance between said planar ports, said first and second plates being shaped and sized to seal said first and second parallel ports, respectively, against pneumatic flow; and a spring coiled about said shaft between said bearing and one of said plates and biasing said assembly in a normal operating mode to simultaneously seal a smaller one of said ports and open a larger one of said ports, a tension of said spring being calibrated to allow said assembly to reciprocate in response to a threshold force applied inteiuiittently thereto to an actuated operating mode to simultaneously seal said larger one of said ports and open said smaller one of said ports.