Abstract: An electro-hydraulic arrangement regulating the lifting mechanism actuatable by a hydraulic motor, on an agricultural working vehicle having a driven wheel, comprises a plurality of sensors including a position sensor forming an actual value position signal, a force sensor forming an actual value force sensor, and an additional sensor forming an actual value slippage signal dependent on slippage of the driven wheel, a nominal value transmitter, a first summation point connected with the additional sensor and with the force sensor so as to obtain the slippage-dependent signal and the actual value force signal therefrom and to produce an output signal, a mixing device having a first input connected with the first summation point and for receiving the output signal and a second input connected with the position sensor for receiving the actual value position signal and producing an output signal, and a second summation point connected with the mixing device for receiving the output signal of the mixing device and

Abstract: A so-called current-regulated end stage for electromagnetic consumers such as magnetic valves or electromagnetic final control elements is provided, in which a field effect transistor takes over the functions of the switch and of the current measuring resistor. When the field effect transistor is conductive, the voltage over a capacitor is made to follow the current flowing through the consumer, and when the field effect transistor is blocked, the flow of current through the free-running circuit is simulated via the capacitor discharge. Both a singlefold and a multiple realization are disclosed, the latter using multiple examples of an RC member and a threshold switch.

Abstract: To prevent a tractor pulling a plow (P) from digging itself in, if the plow position, with respect to soil or tractor level, is controlled by an automatic control system which causes the plow to be lowered if the pulling force of the tractor decreases, slip of the drive wheels of the tractor is sensed and an overriding command signal given to the plow positioning system (S) tending to raise the plow, or, alternatively, a visual indication is given to the operator that the plough should be raised manually; the slip condition is sensed by differentiating a signal representative of plow position, with respect to time, and comparing the so differentiated plow positioning signal (or, in other words, plow dropping speed signal) with a reference which, preferably, includes such factors as tractor engine speed, tractor and/or implement weight, ground wheel adhesion, tractor gearing, and the like.

Abstract: To render the mixing relationship of mixed actual pulling force signals and actual positioning signals independent of the level of the respective individual signals, and thus avoid resetting of a manual positioning command element (7) upon change of respective relationships of pulling force and position, for example depth of furrow of a plough upon change of soil consistency, the force signal is normalized or rendered of equal value with respect to the position signal, preferably in accordance with predetermined events, such as change in the positioning command element, sensing of excessive pulling force, or the like, so that the normalized force signal and the actual position signal will be in balance, and relative change thereof in the mixer will not cause uncontrolled change in the position of the load, for example the plough, without resetting of the command element (or, conversely, require resetting of the command element upon change in relationship of the mixed signals).

Abstract: In a servo system for manipulating a displaceble member in response to movement of a control through corresponding changes of position, which operates by comparing an electrical signal representative of the position of the control with an electrical signal representative of the position of the displaceable member to provide error signals which can drive the displaceable member in either of two opposite directions, a safety interlock circuit is provided which detects the presence of an error signal in either direction immediately after the application of operating voltage or immediately after the switching of the machinery into a different mode of operation and locks the displaceable member in position if an error signal initially appears until the error signal is cancelled by bringing the manual control into a position corresponding with that of the displaceable member. Unexpected sudden movements that may endanger personnel are thereby prevented.

Abstract: An electrohydraulic control unit which regulates the flow of hydraulic fluid to and from one or more consumers by way of a directional control valve has a cylinder for a piston which is mechanically connected with or constitutes the spool of the directional control valve and divides the interior of the cylinder into two plenum chambers connected to the outlet of the pump, either directly or by way of a pressure reducing valve. The chambers are further connected with the tank and each of the fluid supplying and evacuating conduits for each of the two chambers contains a flow restrictor. Th flow restrictors in conduits for admission of fluid to the chambers are mounted upstream of check valves and the flow restrictors in conduits for evacuation of fluid from the chambers are mounted upstream of or constitute integral parts of two solenoid-operated auxiliary valves. The four flow restrictors together constitute a hydraulic bridge circuit.