In conventional “flow control valve and travel switch” control strategy, relative height difference between multiple cylinders only reach accuracy of centimetre grade, which can’t meet synchronous control accuracy requirements of many engineering. In order to improve multiple cylinders synchronous accuracy of the hydraulic lifting system, this paper takes a hydraulic lifting system as basis, which studies PID closed loop control system using electro-hydraulic proportional valve and high-precision displacement accuracy sensor, and the synchronous accuracy of 4 cylinders hydraulic lifting system is improved to millimetre grade.

Crawler transporter is an emerging material handling vehicle for construction of transmission networks in mountainous areas, featuring high efficiency and safety. It consists of a crawler chassis, a remote control system, front and rear carrying gantries which can rise/lower and make left/right turns for smooth running in special terrains, a ginpole for handling of tower, a skip which, together with the carrying gantries, is capable of handling different kinds of materials, and a self-recovery winch. This paper also introduces a series of test methods to ensure safety during handling of material using this type of transporter.

This thesis analyzed the technical characteristics and equipment selection of several methods in realizing the mechanization of waste dumping of deep well foundation, and proposed the development direction of waste dumping machines in our country.

As a special lifting device, the lifting pole is widely used in construction of transmission line powers. Due to the special working environment, a new-type lifting pole made of carbon-fiber reinforced resin matrix composites is designed to facilitate transportation and usage. It is shown by comparison of material properties that new materials can greatly reduce structural self-weight on the condition of ensuring mechanical properties. In order to ensure the equipment is used safely and reliably, this paper carries out mechanical calculation and ANSYS finite element analysis by setting up a mechanical model, and the results show that the design is reasonable and accords with national relevant specifications.

Tower crane is a kind of construction machinery which be widely used in building, bridge, electric power construction. The factor for hoisting a grounded load is one of main factors for dynamic analysis and structure design of tower crane. Different structural forms of tower crane have different effects on the factor for hoisting a grounded load. The finite element models of QTZ125 tower crane with different top-structure form are build and the first six order inherent frequencies and vibration modes are analyzed. Then the factors for hoisting a grounded load at lifting velocity of 0.2~0.5m/s under lifting operation condition are calculated. Based on the results, the influence of the different top-structure of the tower crane to the dynamic characteristic and the factor for hoisting a grounded load is prominent, and the factor for hoisting a grounded load of support-rod type tower crane is less than the tower-cap type tower crane.