Abstract: A metal detector has three magnet/coil units positioned end-to-end. Each magnet/coil unit has a generally rectangular bobbin supporting a coil and a pair of bar magnets at opposite ends thereof. The three coils are connected electrically in a three-phase "Y" configuration. The voltages generated by all three coils are received by a microprocessor-based signal processing unit (SPU). The SPU generates a three difference signals V(x-y), V(y-z) and V(z-x) which represent the differences between the individual coil voltages. The SPU generates a sum signal representing a sum of the absolute values of all the difference signals and generates a trip signal if the sum signal is greater than a threshold. The SPU determines over which side of the coil assembly the piece of metal passes by comparing to a threshold the difference signal corresponding to a difference between the voltages from the coils at opposite ends of the coil assembly.

Abstract: An automatic forage harvester shearbar-cutterhead clearance adjusting system includes motors connected to conventional left and right shearbar adjusting mechanisms. A knock sensor senses contact between the shearbar and the rotating knives of the cutterhead. A control unit including a programmed microprocessor controls the motors and, responding to signals from the knock sensors, automatically adjusts the shearbar-cutterhead clearance. The control unit prevents machine damage by responding to various fault conditions.

Abstract: A material chapping machine, such as a forage harvester, includes a system for automatically controlling the movement of a sharpening stone to sharpen the knives of a rotating cutterhead. Motors move the stone radially towards and away from the cutterhead and laterally across the cutterhead. Contact between the stone and the cutterhead is sensed by knock sensors. The motors are controlled by a programmed microprocessor.

Abstract: A spout aiming control system for a forage harvester includes a sweep mode wherein the spout is automatically moved to provide even wagon filling under certain conditions. A magnetic pickup senses rotation of the forage harvester feed rolls. A disable system prevents operation of the sweep mode unless the feed rolls are rotating faster than a threshold rotation speed. A warning signal is generated if the pickup signal indicates that the feed rolls are not rotating and the pickup has an open circuit condition.

Abstract: A spout control system permits automatic and manual control of a forage harvester spout which directs crop to a receiving wagon. Under certain conditions, the control system automatically sweeps the spout in a stepwise manner through a series of positions to achieve uniform wagon filling. This and other functions are achieved with the use of a suitably programmed microprocessor.

Abstract: A crop-receiving wagon is pivotally attached to a forage harvesting machine with a pivotal crop discharging spout. A dual sensitivity spout-aiming control system maintains the spout-wagon angular relationship within first and second ranges during first and second ranges, respectively, of wagon-machine angles. A switching circuit switches the control system between its sensitivity modes in response to changes in the wagon-machine angle and includes a timer which delays the mode switching for a certain time period after a predetermined change in the wagon-machine angle. A gate circuit cooperates with the timer to reduce the delay period upon manual positioning of the spout.

Abstract: An automatic control system operates to control the spout position on a forage harvester as a function of the position of a crop-receiving wagon and as a function of the relative spout-wagon position. The system includes wagon and spout angle sensors and a variable gain error amplifier for generating an error signal representing the difference therebetween. The gain of the error amplifier is modified according to changes in the wagon position to provide a wagon position dependent amount of free play in the spout-wagon relative position.