Abstract: A new oil leak-off compensating tech in the hydraulic position-holding system is presented. On the basis of the traditional oil-fed compensating in the hydraulic position- holding system, the new tech adds the control of oil which leaks off from the expansion chamber of the hydraulic cylinder to reduce the pressure in it and gain much more bigger pressure difference on the plunger as a result. The analysis results show that, under the same external disturbing force influence, the tech has a very high response speed and control precision with lower oil source pressure and less flux needed. The application of the tech in the synchronism-balancing system of the large-scale forging press has a very nice performance.

Key words: Hydraulic position-holding system, Oil leak-off compensating, Synchronism-balancing system