Abstract: This invention relates to an electromagnetically controlled four-way valve and has as an objective the creation of such a valve as to be exceptionally fast acting and fast cycling, while requiring comparatively little power or force to operate it, a valve that will be especially suited to high flow, low pressure applications, a valve of considerable capacity that does not require a smaller valve to pilot it, or a minimum line pressure and back pressure to actuate it, but does require a slight fluid flow, a valve that will have a low flow resistance factor, a valve that is hermetically sealed to the outside environment, a valve of simple construction (only two moving parts), a valve that is easily and inexpensively produced, a valve in which the application does not require a positive no leak shut-off to flow, but of which application does allow for a neutral position with all ports open, or will require no active neutral position at all--the neutral position only being passed through to make the other positio

Abstract: A hermetically sealed pump for abrasive slurries in which a auxilliary control takes over whenever the pump is unable to complete its stroke and causes rapid jogging reciprocation to dislodge solids which may have settled out and blocked the completion of the stroke.