Elaboration and testing of the articulated car lift
Students Name: Broslavskyi Stepan Stepanovych
Qualification Level: magister
Speciality: Robotics and Mechatronics
Institute: Institute of Mechanical Engineering and Transport
Mode of Study: part
Academic Year: 2020-2021 н.р.
Language of Defence: ukrainian
Abstract: In the first section of the master’s qualification work there were considered the main types and classification features of car lifts and aerial platforms. According to the results of the information review on the subject of the master’s qualification work, the following type of car lift was chosen as a basic prototype for further calculation and design: - by purpose – general purpose; - on a design of the working equipment – four-section; - if it is possible to turn the working equipment – non-rotating (at an angle < 360 °); - by the design of the chassis – trailed; - on the principle of drive of working movements – electrohydraulic (drives of all sections of lifting of an arrow and drives of extension of folding support – hydraulic; drive of the mechanism of turn – electric); - by type of support frame – with sliding folding supports. The initial data for the calculation are the maximum lifting height of the cargo platform 15 m, the maximum departure – 10 m. In the second section of the master’s qualification work the constructive and functional features of the developed layout solution of the articulated four-section elevator are considered. The lift is mounted on a car trailer with a wheeled chassis. Four folding supports constructed on the basis of parallelogram mechanisms with hydraulic drives are used as the system of fixing of the lift. The base of the lift has the ability to rotate around a vertical axis with a special electromechanical drive. The sections are connected in pairs by means of elbow inserts, which retain their positions due to the use of parallelogram mechanisms. All sections are driven by hydraulic cylinders. The mounting platform has the ability to change its position due to a separate hydraulic drive. The lifting section is telescopic, i.e., it is able to change its length due to the elongation-retraction of the hydraulic cylinder rod. To connect the trailer to the towbar of the tractor, a special lock with a wheel support is used. Based on the proposed design of the lift, its simplified design scheme was developed. The lift mechanism consists of a fixed base and five movable links. The knees were considered conditionally immobile, as their movements are limited by special parallelogram mechanisms. All links are interconnected by means of hinged supports, which are single-moving (rotating) kinematic pairs of the fifth class. The telescopic section of the lift consists of links that are interconnected by a slider - a single-motion (translational) kinematic pair of the fifth class. The degree of freedom of the lift mechanism is equal to five. The equation of motion of the elevator mounting platform was derived from the five selected generalized coordinates. Based on the derived analytical dependences (2.2) - (2.9), the numerical simulation of the movement of the lifting platform in the software product MathCad was performed. To analyze the correctness of the derived dependencies, in parallel with the numerical simulation, simulation of the motion of the solid model of the lift mechanism in the software product SolidWorks will be performed. Based on the results of numerical and simulation modeling, it is concluded that the nature of the simulated trajectories coincides, while some inaccuracies in the numerical values of maximum and minimum deviations of the platform can be explained by simplifications adopted in creating the calculation scheme of the lift mechanism. To ensure the parallelism of the support surface of the mounting platform to the horizon and to extend the telescopic section of the boom in its design, it was proposed to use double-acting power cylinders in which the rod moves in both directions under working fluid pressure. These hydraulic cylinders were calculated in the second section. The object of development and research is a car-type articulated hoist, built on the basis of a car trailer with a wheel chassis. Subject of calculation and research – kinematic and power parameters of the elements of the articulated lift; design parameters of power hydraulic cylinders of the mounting platform and telescopic section of the lift. The purpose of work - development of the constructive decision and research of separate kinematic and power parameters of the automobile lift of articulated type. Key words – kinematic analysis, power analysis, mechanism, hydraulic cylinder, wheel chassis, simulation.