Determination of Maximum Calculated Total Values of Wind Loads on the Elements of Anti-Theft Device from Eccentric and Wedge Mechanism

Abstract

To carry out a power calculation of the anti-driveaway device (from now on referred to as – AD) of lifting cranes operating in the open air, it is necessary to know the maximum calculated value of the wind force on the elements of the AD rails connected by side bars. The various types of anti-theft crane devices recommended for use have a number of disadvantages, which have been written about in previous papers. Anti-theft crane devices are also known, in which the stop of lifting cranes on the rail track is carried out by a locking eccentric interacting with the surface of the rail head. The reliabi-lity of such devices is insufficient, since due to the constant force of the spring, the adhesion force of the eccentric to the rail does not depend on the changing wind force. To carry out a power calculation of the anti-theft device for cranes operating in the open air, it is necessary to know the maximum calculated value of the wind force acting on its elements that hold the cranes on the rails when the cranes are inoperative. When a crane moves along rails under the influence of wind force Pw, the eccentric, turning, transmits the pressure force from the rail to the double-arm lever connecting the eccentric mechanism to the wedge mechanism. The eccentric mechanism is essentially a drive for the vertical movement of the wedge, as a result of which the pincer clamp closes on the rail head and the crane stops. Thus, the energy developed by the crane, driven by the force Pw, is used to stop it. For this purpose, the paper deals with the issues of determining the maximum design values of the wind force acting on the total lateral surfaces of various types of cranes under different climatic, aerodynamic, probabilistic and other wind loads. A methodology is given for determining the maximum calculated total values of wind loads on the elements of the developed anti-theft device for lifting cranes moving along crane rail tracks. The calculated total lateral areas and wind loads on bridge support single- and double-girder cranes, gantry and tower cranes for various designs, spans, load capacities and other parameters have been determined. Based on the calculations performed, it is possible to create a model range of anti-theft devices for various designs of load-lifting cranes moving on crane rails under various operating conditions.