Abstract: A valve shutoff mechanism for automatically operating a gas valve, a liquid valve or the like to shut off the flow of fluid in a pipeline in response to an earthquake, temperature changes and/or an electrical or mechanical signal generated by an associated mechanism. The housing, formed of complementary, symmetric half portions, encloses a spring bias motor, a torque arm assembly coupled to the spring motor for rotation about a first axis, a latch assembly for normally preventing rotation of the torque arm assembly, and a triggerable catch assembly for normally maintaining the latch assembly in contact with the torque arm assembly and for enabling the latch assembly to disengage the torque arm assembly in response to seismic vibrations of predetermined magnitude and acceleration, an externally generated electrical signal, temperature changes of predetermined magnitude or a combination thereof.

Abstract: A vibration sensitive valve operating device capable of being tuned to vibrations of predetermined magnitude, such as earthquake-type vibrations of a magnitude causing serious threshold structural damage, and incorporating a latch assembly and triggerable catch assembly providing great force amplification between the holding force, which is a ball weight received in a balance plate concave depression of predetermined contour, and a large mechanical force, e.g. the force exerted on a spring loaded torque arm coupled to a valve stem. The latch assembly includes one or more rail members carrying first and second bearings and pivotable about an axis parallel to the operational axis of the associated valve, the first bearing being engaged with the free end of the torque arm when the device is latched. The catch assembly includes a trigger arm frictionally coupled to the balance plate for rotation therewith about another axis parallel to the latch and valve axes noted and normally engaged with the second bearing.