Abstract: A four-way hydraulic control valve automatically reverses flow of hydraulic fluid to a double acting hydraulic cylinder or to a reversible hydraulic motor when a substantial resistance to fluid flow is encountered, such as when the cylinder or a machine being operated by the cylinder or motor reaches a mechanical limit of its motion. The valve has a reciprocating spool in a valve body with two internal control valves, one at each end, and with appropriate internal pressure shunts for directing high pressure fluid into the control valves and drain fluid restrictions to shuttle the spool back and forth in response to an increase in pressure resulting from a substantial resistance to fluid flow.

Abstract: A three-point hitch mounted in-row tiller has a conventional three-point hitch mounted frame member with an outrigger arm pivotally mounted to the frame member in a manner that accommodates pivotal movement of the outrigger in relation to the frame member about two orthogonal axes. Pivotal movement about one of the axes causes tilting of a working tool mounted on the outrigger arm, and pivotal movement about the other axis causes vertical lifting and depth control of the working tool. Various working tool embodiments, including several with flexible teeth, and a mechanical/hydraulic sensor apparatus are also included.