Abstract: The present invention is directed for use in a valve assembly including a housing having an axis and defining an interior, with fluid provided in the housing and substantially filling the housing interior, a valve stem disposed in the housing interior and a piston attached to the valve stem, wherein the piston and valve stem are moveable along the housing axis within the housing interior between first and second positions. The present invention includes a valve actuation control device disposed in the housing interior, the valve actuation control device allowing the fluid to freely flow from one side of the piston to the other side during at least a portion of the piston's movement between the first and second positions.

Abstract: For use in a valve assembly including a housing having an axis and defining an interior, with fluid provided in the housing and substantially filling the housing interior, a valve stem disposed in the housing interior and a piston attached to the valve stem, wherein the piston and valve stem are moveable along the housing axis within the housing interior between first and second positions, a valve actuation control device is provided which is disposed in the housing interior, the valve actuation control device allowing the fluid to freely flow from one side of the piston to the other side during only a first portion of the piston's movement between the first and second positions.

Abstract: The present invention is directed for use in a valve assembly including a housing having an axis and defining an interior, with fluid provided in the housing and substantially filling the housing interior, a valve stem disposed in the housing interior and a piston attached to the valve stem, wherein the piston and valve stem are moveable along the housing axis within the housing interior between first and second positions. The present invention includes a valve actuation control device disposed in the housing interior, the valve actuation control device allowing the fluid to freely flow from one side of the piston to the other side during at least a portion of the piston's movement between the first and second positions.

Abstract: The present invention provides a segmented cover system utilizing a series of cover sections, which can be of any size and shape, and a series of curved or straight supporting bows to form a cover assembly which allows for the easy replacement of a cover section or a bow without disassembling the entire cover system. The present cover assembly preferably utilizes a series of standard cover sections which are detachably secured to the two adjacent supporting bows. Preferably, the supporting bows are curved and consist of a bow center section and two easily removable bow end sections. The unique design, construction and interaction of the cover sections, the bow center sections and the bow ends enable damaged cover sections and bows to easily be removed and replaced without disassembling or removing the cover system from its location. A drive assembly can be used to extend and retract the segmented cover system of the present invention.

Abstract: A valve stem actuator for a slurry valve or the like includes a support frame extending from the valve body to a linear operator having a cylinder and piston. Means are provided for connecting the piston rod to the valve stem and means reciprocally mounted on the support frame rotate the valve stem with respect to the valve body independently of the linear movement of the valve stem to dislodge accumulated crust to permit the valve disc to properly seat to prevent fluid flow through the valve. The linear operator is preferably pneumatically or hydraulically actuated and the rotary actuator preferably comprises an air or hydraulically actuated rack engageable with the valve stem. The valve stem actuator is useful for new valves or for retrofit of present slurry valves or the like.