Abstract: Precisely recurrently controllable dropwise oilers or other liquid-feeds for apparatus having some optimal-requirement of oil or other liquid-feed to be supplied gravitationally dropwise from an outlet-line emanating from a lofty reservoir. A solenoid actuatable reciprocatable plunger-valve effects intermittent liquid-feed flow along the outlet-line toward a liquid drop-former element spaced a vertical-gap above an apparatus intake-line. For recurring like time-periods, infrared or other electromagnetic detector detects liquid-feed droplets falling from the drop-former so that the liquid-feeder operator might during recurring like time-periods have the solenoid reciprocation adjusted toward the achievement of a dropwise liquid-feed rate tending to converge upon the apparatus optimal-requirement.

Abstract: Disclosed are central-pillar assemblies wherein the various components are precision assembled at a factory location in a modular form for safe shipment to remote farmsteads and there easily reliably installed by relatively unskilled personnel. The assembly comprises an upwardly convergent tubular column serving both to structurally support and to supply water to an outflow-elbow portion for the irrigation apparatus, the tubular column being intersected by a water inlet-pipe and by a slanting oblique-pipe. There is a linear drive-conduit for the apparatus electrical commutation portion and taking a slanting posture wherein it is surrounded by and is in water impervious sealing relationship to the oblique-pipe and to the outflow-elbow. Housing for the electrical commutation is disposed below the oblique-pipe and is securely attached to the tubular column.