Abstract: The operation of a boom-type crane or the like is monitored or controlled and, especially, a setpoint signal is generated which represents the total load moment for any given set of crane-operating parameters so that this setpoint signal can be compared with an actual-value signal and the crane operator alerted or crane operation terminated when the actual value of the boom-load moment approaches the maximum permissible value thereof. According to the invention, three storage units are provided, the first storing a value of the crane-boom intrinsic moment as a function of the crane parameters, the second storing a unit-load moment value as a function of the crane parameters and the third storing values of the maximum permissible load moment per unit load.

Abstract: A crane boom pivotal about a horizontal axis is monitored as to loading over a prolonged period, e.g. a period of about 24 hours, by providing a position-dependent output representing the maximum permissible load moment on the boom at a particular position thereof relative to its support and a load sensor responsive to the instantaneous loading (load moment) of the boom. These two sensors provide inputs to a quotient-forming comparator whose output is applied to a 24-hour disk or tape recorder. The output of the quotient-forming comparator also controls a device for immobilizing the drive system for the boom, preventing it from exceeding its maximum permissible load.

Abstract: A crane boom, pivoted at one end to the chassis or body of the crane, is swung about a horizontal axis by a hydraulic drive mechanism, e.g. a double-acting piston-and-cylinder arrangement. A control system for this boom comprises a device which monitors the instantaneous load moment on the boom and the maximum load moment permissible for the particular position of the boom (as a function of this position) and compares these two parameters in a quotient-forming comparator whose output is applied to a set point adjusting element via a logic circuit or connection device. The set point generating unit forms part of the actuating system for the crane.