Abstract: Apparatus for controlling the cutting depth of a road grooving machine by vertical adjustment of both the front and rear travelling gear on the basis of a cutting depth control signal, which is generated by a tracer ski by sampling a reference plane, including at least three ultrasonic sensors arranged one behind the other in the direction of movement of the cutter, and an evaluation means for determining the distances between the ultrasonic sensors and a reference plane to derive therefrom an inclination signal as well as an averaged distance signal. The evaluation means controls the height of the two travelling gears such that the average distance of the cutter drum as well as the position of the machine relative to the reference plane are adjusted.

Abstract: An ultrasonic sensor control unit for a road finishing machine for generating a height control signal for a vertically adjustable beam, the ultrasonic sensor control unit including at least three ultrasonic sensors which are arranged at a considerable distance from the beam in the direction of motion of the road finishing machine. The ultrasonic sensor signals determine the distances between each ultrasonic sensor and a reference surface, the values which lie more than a predetermined distance outside of a plane which is determined by the measuring points associated with the other distances being rejected as faulty measurement. On the basis of the height signals, the mutual distances of the sensors, and the distance between a sensor and the rear edge of the beam, the evaluation means calculates the projected height at the rear edge of the beam. This height is compared with a selectable desired thickness value.

Abstract: A height-position sensing device for use with a contol circuit for controlling the height position of a blade in the case of a motor grader includes a mechanical height-position sensor and a ultrasonic height-position sensor which are connected to a common control circuit via a switch.

Abstract: The invention relates to a depth measuring apparatus for a dredger, comprising an inclination sensor mounted on the dredger arm, a receiver for receiving a radiation establishing a reference level, and an evaluation circuit connected to the receiver and to the inclination sensor. In a known measuring apparatus of this type, the receiver merely serves for calibrating a pressure sensor operative to indicate the position of the dredger arm relative to the body of the dredger. According to the invention, for improving the measuring accuracy the receiver is itself operable to determine the position of the radiation determining the reference level relative to the receiver, the thus obtained information being employed together with the inclination signal for determining the operating depth of the dredger scoop.

Abstract: The present invention relates to an opto-electronic measuring receiver for determining the relative position of the measuring receiver with respect to a radiation plane established by an optical transmitter. The measuring receiver comprises a plurality of opto-electronic receiving units for generating an output signal indicative of the impingement of the radiation plane on a respective receiving unit. Known opto-electronic measuring receivers having a great number of receiving units require a correspondingly extensive circuitry. For avoiding this disadvantage, the invention provides that each receiving unit is connected to a controlled commutator element, that there is provided a control circuit in connection with the commutator elements, that the first and second outputs of each commutator element are connected respectively to the first and second inputs of the control circuit, and that the control circuit includes memory means for storing an information relating to any one of the receiving units.