Article citation info: (*) Tekst artykułu w polskiej wersji językowej dostępny w elektronicznym wydaniu kwartalnika na stronie www.ein.org.pl IntroductionBesides the reliability, main requirements for vertical transport are positioning, use of power and reducing of the dynamic loads. For the hoisting mechanism the worst case in terms of appearing overloads is when the lifting operation starts when ropes have clearance. This case is called a jerk of a payload. The case when the ropes clearance is so big that when the ropes tensing began, the angular speed of the drum is near the reference speed. The research of overloads in drive systems usually comes up in the context of their impact on the steel structures of devices. For example in papers [1], [7] and [11] the tests of load dynamics of steel structures of the overhead cranes during payloads lifting were described. In [14], authors presented the model of the hoisting mechanism, where the stiffness of the girder has been taken into account. In these articles there were presented the studies of the behavior of the cranes structures under dynamic loads using FEM method. In [15] the influence of the hoisting mechanism operation on the crane structure was presented. There were presented waveforms of forces in ropes for different methods of increasing the drum speed from linear to inertial with various time constants. The problem of the crane structures load by vertical dynamic forces appeared also in [4] and [16], where the systems with moving mass were described. Reduction of dynamic overloads made by hoisting mechanisms operation provides measurable exploitation benefits, such as: minimization of the structure overload or reducing the power consumption. There were presented also methods of reduction of the steel structure loads by using dampers, eg. in [9]. Research of overloads of hoisting winches for varies cases of lifting were described in [12]. The authors of [10] worked on modeling of hoisting mechanisms equipped with different drive systems.The authors of [3] paid attention to necessity of consideration the various types of the loads of mechanisms caused eg. by the control methods and the limited scope of application of the cranes automation. The conclusion is that the control systems which reduce a temporary load should be used both for automatic and manual control of hoisting winches.In [5] authors pointed the specificity of drives of hoisting winches, which: "are distinguished with respect of their requirements, regarding the control of speed and position and the acceleration phase carried with an active load". The usage of modern drive systems based on frequency inverters, allows meet these requirements.As can be seen the problem of overloads of hoisting mechanisms appears mainly in context of dynamic loads of supporting structures or research of dynamics of hoisting mechanisms. In our opinion, which is based on reading the available literature, the issues of reduce dynamic loads is presented only in context described above.In the paper there is present...

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EnErgy consumption and EnErgy EfficiEncy improvEmEnt of ovErhEad cranE's mEchanisms EnErgochłonność i poprawa EfEktywności EnErgEtycznEj mEchanizmów suwnicy pomostowEjThe article presents the numerical investigation of the overhead crane's energy consumption. The analysis is based on the hybrid model of the crane consisting of numerical model of drive mechanisms as bridge, trolley, hoist and also experimentally measured power consumption of each control unit. The numerical model was verified experimentally on the real crane. The investigation focuses on analyzing the energy consumption of the overhead crane in relation both to the travelled distance and also for the lifting and lowering heights of a suspended payload. Particular attention was paid on the cases straightly related to the hoist, as a main factor of improvements in the energetic efficiency of the overhead crane. Energy consumption was investigated for a variety of magnitudes of transported mass.

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