Study On Typical Failure Of Lifting System Of A Crane

As the main movement system,the winch system plays a very important role in the lifting system of the crane.Its main movement is the rise and fall of the load.The stability and reliable working capacity of the lifting system are important indicators of the performance of the crane.Based on the school-enterprise cooperation project and taking the 80-ton truck crane as the research object,this paper studies the two common faults in the lifting process,namely,the stall in the lifting process and the shaking phenomenon in the lifting process.Through experiments,problems are found and influencing factors are analyzed,and targeted improvement schemes are proposed.The main contents are as follows:1.This paper briefly introduces the research status and development trend of automobile crane and its lifting system,analyzes the common faults of the lifting system of automobile crane,and determines the research direction as the stall of winch and the shaking phenomenon in the lifting process,and analyzes the harm of the two kinds of faults respectively.2.Based on the working principle of crane lifting system,the internal structure of lifting system is studied,and the key components,such as load sensitive variable pump,multipath valve,balance valve,brake and winch motor,are analyzed.3.The test found that the jitter and the stall occurred in the lifting system of automobile crane.Through the specific working condition design,it was found that the stability of the lifting system deteriorated with the decrease of the opening pressure range of the balance valve.As the preload of the brake drops until the brake is fully open,the opening pressure of the brake drops,and the pressure flu ctuation of the balance valve mouth gradually decreases until the jitter disappears when the brake is fully open.Stalling during a fall is significantly more severe than during a rise;The instability of the lifting system increases with the increase of the variable ratio of motor falling process.On the basis of the above analysis,the causes of jitter and stall are analyzed.4.By comparing the two ways of thinking to improve the lifting system,the disadvantages of the opening scheme by increasing the brake opening pressure and delaying the brake until the balance valve is in working state are analyzed.Then through the improvement of pump return circuit,the problem of stall is basically solved.The rationality of the improved scheme is verified by hoisting tests at different speeds.