Abstract: The invention relates to a method for starting at least one asynchronous electric motor of a large hydraulic excavator having a service weight >100 t and having an electrohydraulic drive, in that the particular electric motor is transferred from an idle position to an operating position by using a three-stage motor starting process, wherein the volumetric flow rate of at least one hydraulic pump operatively connected to the electric motor is set to the delivery rate V=0 during all starting stages of the electric motor and the delivery rate V of the hydraulic pump is controlled to a value >0 only after the last starting stage of the electric motor by activating an actuator.

Abstract: The invention relates to a method for regulation of a cooling fan drive on an internal combustion engine, in particular equipped with several independent cooling circuits, in a construction or working machine, whereby the power drain of the cooling fan drive is set to approximately zero during certain working stages of the construction and/or working and said power drain may be added to the capacity for the working stage.

Abstract: An arrangement for operating a diesel-hydraulic drive on a construction machine in limit-load control with a microprocessor controller in which the installed hydraulic power is greater than the rated output of the diesel engine. Upon thermal and/or diesel-engine overload the hydraulic power which can be taken off is reducible; in the case of non-output loading, after a selectably predetermined time the diesel engine can be switched to idling speed of rotation and hydraulic displacement pumps can be operated with minimum delivery oil quantity; and the adjustable hydraulic displacement pumps can be adjusted in accordance with selectably predeterminable output curves.

Abstract: An electronically controlled pipe fracture safety device for operating devices which are fed by a hydraulic pump and which are actuated by a control slide value by means of hydraulic cylinders. Control lines branch off from lines which lead from the hydraulic pump via a control slide valve to the hydraulic cylinders, the control lines feeding the hydraulic medium to a differential flow monitor, on the piston of which a permanent magnet is fastened. The latter, by means of a reed contact as a result of a pressure difference existing between the control lines, which pressure difference is brought about by damage or fracture of a line, produces a signal in the NOR gate, the latter forming the input of a scoring logic. This signal retransmits a self-holding signal to NAND-gates which form a flip-flop. The self-holding signal causes deenergization of a relay and consequently an interruption of the current flow to the control slide valve and brings about the locking position of the latter.