A control system for an industrial vehicle having an articulated frame with front and rear movably connected frame halves. The control system includes a steering mechanism disposed between the frame halves and is configured to pivot the rear frame half about the front frame half. A first hydraulic actuator is operably connected with the steering mechanism. An offset mechanism is disposed between the frame halves and is configured to displace the rear frame half with respect to the front frame half in a direction generally toward one of the lateral sides of the vehicle. A second hydraulic actuator is operably connected with the offset mechanism. A hydraulic circuit includes a hydraulic fluid source and a selector valve device connected with the fluid source and with each of the first and second actuators. The selector valve is configured to selectively direct hydraulic fluid to the first actuator to operate the steering mechanism and alternatively to the second actuator to operate the offset mechanism. An operator controller device is connected with the hydraulic circuit and is configured to adjust hydraulic flow between the fluid source and the selector valve device so as to control extent and direction of movement of the rear frame half by the selectively operated steering mechanism or offset mechanism. Furthermore, an operator input device is connected with the selector valve device and is configured to operate the selector valve to selectively direct fluid to one of the two actuators.

A multiple fluid flow controller valve device having radially disposed a number of valves and a central rotary shaft with cam surfaces functioning as the valve controller to open and close the valves in the desired sequence.

A rotary indexing valve has an electromagnetic coil which shuttles a spoil axially. As the spool shuttles axially, it cams on axially opposed surfaces so as to rotatably index the spool. Such rotatable indexing of the spool angularly positions different sized orifices into or out of registration with one of the ports in the housing to change the cross sectional area of the flow passage between the inlet and outlet ports of the housing. One of the cam surfaces is defined by an alternating series of peaks and valleys, and the valleys are at different heights so as to change the spacing between the spool and a pole piece, which varies the inductance of the coil dependent on the angular position of the spool. The inductance of the coil can therefore be measured to provide an electrical signal indicative of the angular position of the spool.

The invention is directed to a foldable agricultural implement frame having an extended working configuration and a folded transport configuration. The frame comprises a center section and two wing section. Each of the wing sections have row markers that are extended and retracted by a row marker hydraulic circuit. The row marker hydraulic circuit is provided with first and second supply/return lines each having a two-position latching valve. A mechanical linkage comprising a rod extends between the center section and one of the wing sections, for shifting the latching valves to their checked position, when the implement frame is folded from its working configuration to its transport configuration. The latching valves lock the row markers in their retracted transport position.

Disclosed is a method for controlling the above-ground "raise height" of a seed-planting row unit on an agricultural planter having a row marker, a marker switch and a positioning assembly such as a solenoid valve and hydraulic cylinder for raising and lowering the row unit. The method includes enabling the positioning assembly to raise the row unit and changing the marker switch from its first to its second position when the row unit reaches a predetermined height. The positioning assembly is thereby disabled. Such assembly is re-enabled after a brief time delay. The method is carried out using a unique implement control circuit connected to the marker switch and the positioning assembly.