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This article introduce a kind of displacement sensor and the matching circuits with it. The sensor can be used to measure the displacement of cartridge insert valve in the medium of pressure with amplitude ranged from 0 Mpa to 32 Mpa.

Paper illustrates a steering system of a lifting robot vehicle which is used for assembling and disassembling the active wheel of blower mill in power station. The whole steering system is controlled by a microprocessor. The axles of the four wheels are driven hydraulically. Proportional valves, which are controlled by the output signals of microprocessor calculated from the rotation angle of steering wheel, are used to control the flow into the cylinder. The step response of the system is calculated by digital simulation and the calculated result is compared with the experimental result, They are close to each other.

Base on the experience of practical operation and the results of model test, paper points out the features of tensioner hydraulic system and two main troubles that often cause the damage of hydraulic components. The mathematical model of the system is analyzed and the pressure response is calculated with respect to the step input of torque on hydraulic actuator. This calculated result agrees with our experimental result. For overcoming the shortage of pressure impulse, the measure of “prebuilding up pressure” is suggested, which was tested in our laboratory. The test proofs that this measure can effectively prevent pressure impulse caused by starting under full load.

Paper introduces a new type of small displacement sensor. It has the characteristics of high sensitivety, high pressure resistant, non-contact type etc. The sensor was used in measuring the displacement of the valve cone of a cartridge valve and the results were fairly satisfied.

Nowadays, the design of radiator of hydraulic system is based on the equilibrium temperature, i.e. under that temperature the heat energy generated by system is equal to the heat energy dissipated. When the working time is not long, the oil temperature can't reach the equilibrium temperature. If the design is still based on the equilibrium temperature, the designed radiator will be larger than needed. This paper studies the temperature rising transient of hydraulic system and suggests a new method of radiator design, which can rationally determine the dissipating area of radiator. This method have been used in the radiator design of a hydraulic crane and get a satisfied result.

When the speed of actuator is quickly changed in hydraulic system, the great pressure surge and noise are generally caused. In this paper, the optimal control for the minimum pressure surge in shortest speed conversion time is approached. The optimal control is obtained by applying the Pontryagin's Maximum Principle. Experimental results and simulation calculation show that using the optimal control can reduce the pressure surge to about 5 times in comparison with that of step input.

If the hydraulic system or component is analysed by the method of bridge circuit analysis, the hydraulic system or component can be expressed by several elementary symbols, the arrangement of system will be more clear and the relation between elements will be more unequivocal. Paper gives out an analysis of hydraulic velocity regulating system by the method of bridge circuit analysis. Its step response by computer calculation is also presented.

In this paper, in the analysis of differential cylinder not only the speed and speed ratio of cylinder but also the resistance of circuit have been taken into account. Based on the point of view of minimum energy consumption, an idea of “optimum differential ratio” has been proposed. Under the condition of optimum differential ratio, the circuit satisfies the demanded piston thrust and velocity, and the energy consumption is mimimum. Paper also proposes a procedure of how to design a differential cylinder by using the idea of optimum differential ratio. Finally, the idea of optimum differential ratio is used to analyze a circuit of hydraulic crane.