Abstract: Hydraulic impact often occurs when the control valve shuts down or the load movement reverses suddenly in hydraulic transmission system. Hydraulic impact influences smoothness and stable running of hydraulic system, reduces the service life of hydraulic elements, and even makes the actuator have false action which leads to the accidents that can be illustrated by the hydraulic control circuit of the slipping arm of cinder scraper of steeling-making furnace. The high load inertia and frequent alternating direction lead to the serious hydraulic impact which shorten the age limit of the hydraulic motor driving the cinder scraper’s slipping arm and make the hydraulic motor changed frequently, thus to affect the production efficiency. In order to improve this phenomenon, the hydraulic impact in large inertia load’s hydraulic system is analyzed, and a method is proposed to alleviate the hydraulic impact. This method is to pre-calculate the time when the peak pressure arrives by controlling signals, and adjust the variable damping used in buffing the impact so as to reduce the hydraulic impact. The principle of this approach is explained in theory which is verified by digital simulation and field test. The result of simulation and field test testifies the method bears the advantages of being quick dynamic and having low energy consumption, which can reduce the hydraulic impact effectively in the premise of satisfying the characteristic of system response.

Key words: hydraulic impact;peak pressure;system simulation;valve-controlling hydraulic motor