| 摘要 |
A hydraulic system for operating a working device, such as a hand tool, at a distance from a hydraulic-oil pressure source, wherein the working device is driven by means of a single-acting hydraulic cylinder. To enable the hydraulic cylinder to be connected by means of one single line, the system includes a valve (17) which is connected to the pressure source (10), with associated tank (8), and which has a pressure port for receiving hydraulic oil from the pressure source (10) and a return port for delivering return oil to the tank (8), and a working port for delivering hydraulic oil to and receiving return oil from the hydraulic cylinder through the medium of one single, common pressure-and-return line connected between the valve and the cylinder. The valve (17) is adapted to be controlled by the inlet pressure acting on a valve slide which can be adjusted positionally against a spring tension force, such that when the valve slide is in a rest position, i.e. at low inlet pressure, the working port will communicate with the return port, whereas when the inlet pressure is increased the slide setting is adjusted against the action of spring biassing force so that the working port will communicate with the pressure port. This enables the hydraulic cylinder to be driven by one single line (6) and to be controlled by the pressure applied on the valve (17). |
