Abstract: The invention relates to a method for determining a present value of the capacity level of a hydraulic crane (1) provided with a lifting cylinder (8), the present value of the capacity level being determined by means of a processing unit (33). The initiation of each new lifting cycle of the crane is detected and a minimum value of each lifting cycle is registered, which represents the lowest hydraulic pressure on the piston side (8a) of the lifting cylinder during the lifting cycle or the lowest cylinder force of the lifting cylinder during the lifting cycle. For at least some of the lifting cycles, the processing unit (33) determines the present value of the capacity level of the crane taking into account a control value (Vc) corresponding to: the minimum value registered for the previous lifting cycle, or the lowest one of the minimum value registered for the previous lifting cycle and the minimum value registered for the present lifting cycle.

Abstract: The invention relates to a method for determining a present value of the capacity level of a hydraulic crane (1) provided with a lifting cylinder (8), the present value of the capacity level being determined by means of a processing unit (33). The initiation of each new lifting cycle of the crane is detected and a minimum value of each lifting cycle is registered, which represents the lowest hydraulic pressure on the piston side (8a) of the lifting cylinder during the lifting cycle or the lowest cylinder force of the lifting cylinder during the lifting cycle. For at least some of the lifting cycles, the processing unit (33) determines the present value of the capacity level of the crane taking into account a control value (VC) corresponding to: the minimum value registered for the previous lifting cycle, or the lowest one of the minimum value registered for the previous lifting cycle and the minimum value registered for the present lifting cycle.

Abstract: An extendible crane boom comprises a number of telescopic boom sections, which are each composed of a tube and a holder mounted at an outer end of the tube and serving as an attachment for a double-acting hydraulic cylinder which serves to displace the individual telescopic boom section out of or into an immediately preceding boom section so as to extend and shorten, respectively, the crane boom in its entirety. The cylinder part (7) of each hydraulic cylinder is connected to the holder via a coupling comprising a screw joint having several screws, and a pair of cooperating male and female members (11, 9), one of which has a part-spherical surface (18) which faces the other and which, when the screw joint is but loosely tightened, allows adjusting the cylinder part into a desired, correct working position in relation to the holder, in which position the screw joint (13) is finally tightened.

Abstract: A dual control for vehicular cranes comprises two separate control units with control levers cooperating in pairs, which levers are protected by casings (7, 7') consisting of pivotable shell parts (9, 9') which in a closed position enclose and protect the control levers and in an open position expose the levers. In the two casings (7, 7') are arranged analogous locking mechanisms (14, 14') which comprise locking means (15, 15') being movable between locking and releasing positions. The two locking mechanisms are coupled to a transmission (18) which in a neutral position permits that the one casing (7') is opened and that in connection therewith transfers the opening motion of the movable shell part (9) to the locking mechanism of the other casing (7) in order to secure its locking means (15) in the locking position and, thereby, make the opening of the other casing (7) impossible as soon as the first one (7') is opened.

Abstract: An extendible crane boom comprises, in addition to a tubular base boom section (1), a plurality of boom sections (2, 3, 4, 5) telescopically within the base boom section and each composed of a tube and a holder (8, 8', 8", 8"') mounted at an outer end thereof for connecting the tube to a double-acting hydraulic cylinder (9, 9', 9", 9"') with a view to displacing each boom section out of and into an immediately preceding boom section so as to lengthen and shorten, respectively, the crane boom in its entirety. The third and fourth hydraulic cylinders (9", 9"') are located in a first plane which is parallel to the longitudinal extent of the boom and located inwardly of a second plane, in which the first and second hydraulic cylinders (9, 9') are located. This minimizes the overall height of the outermost telescopic boom sections (4, 5), counted as the center distance between the telescopic tube concerned and the associated hydraulic cylinder.