System for a crane boom
First Claim
1. In a drive for a crane having a boom, a manually actuatable unit controlling the displacement of said boom, a drive unit controlled by said manually actuatable unit for displacing said boom, and a monitoring unit for measuring the load moment on said boom, the improvement which comprises a logic element in said drive unit for controlling the speed of said boom, said monitoring unit comprising means for generating an output signal representing the quotient of the instantaneous load moment of said boom and the maximum permissible load moment for the instantaneous position thereof, and means for applying said output signal to said logic element for controlling the speed of said boom upon operation of said manually actuatable unit to reduce said speed upon increasein the amplitude of said quotient.
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Accused Products
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.
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Citations
10 Claims
- 1. In a drive for a crane having a boom, a manually actuatable unit controlling the displacement of said boom, a drive unit controlled by said manually actuatable unit for displacing said boom, and a monitoring unit for measuring the load moment on said boom, the improvement which comprises a logic element in said drive unit for controlling the speed of said boom, said monitoring unit comprising means for generating an output signal representing the quotient of the instantaneous load moment of said boom and the maximum permissible load moment for the instantaneous position thereof, and means for applying said output signal to said logic element for controlling the speed of said boom upon operation of said manually actuatable unit to reduce said speed upon increasein the amplitude of said quotient.
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8. A method of controlling a crane boom comprising the steps of:
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a. generating a first signal representing the instantaneous load moment on said boom; b. generating a second signal representing the maximum permissible load moment of said boom at each instantaneous position thereof; c. forming the quotient of said first and second signals and producing a monotonic output signal representing the loading of said boom; d. generating a control signal in response to manual actuation of an element to cause displacement of said boom as a function of the displacement of said element; and e. modifying said control signal in accordance with said output signal to prevent overloading of said boom by reducing the rate of displacement of said boom as said quotient increases. - View Dependent Claims (9, 10)
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Specification