Valve actuating mechanism fitted on stem extension - has hydraulic ram enclosed at one end by air pressure receiver opposing hydraulic pressure

摘要

The valve actuating mechanism fits on an extension of the valve stem whose movement opens and shuts it. It has a hydraulic ram with a rod (16) fixed to one face of its piston (14) and protruding beyond the cylinder (12) in the direction of the valve, via an opening in the cylinder end incorporating a seal. An extension of this rod is coupled to the valve spindle. The other end of the ram cylinder is enclosed by a high-pressure air receiver (30), the pressure acting against the other piston face. A stop (40) is fitted in the cylinder, to restrict the amt. of movement of the piston towards the receiver under the effect of the hydraulic pressure, typically in the form of a ring screwing into the cylinder end.