New solution to increase the safety of operating system with hydrostatic drive

Hydraulic actuators that commonly used in machine work systems are not equipped with protection features preventing the autonomous insertion and extension of a piston rod because of the influence of external forces. Consequently, a spontaneous fall of working circuits in the event of the loss of tightness of supply lines of an actuator may occur. Currently applied safety features that are sometimes mounted directly on hydraulic cylinders as in the case of mining machinery intended for exploitation in black coal mines protect working systems from uncontrolled lowering. However, their design forces the drive to be started to make it safe to leave the work system. If, for any reason, the drive system of a machine cannot be started and the work system is raised, its lowering can take place only by unsealing the hydraulic system, which is unforeseeable for constructors and carries the danger of crushing a person or persons involved. The paper presents a new solution for hydraulic cylinders, which enables, among other things, the controlled and safe insertion of a piston rod under load without the need for having the drive system started.