| 摘要 |
<p>PURPOSE: To reduce the occurrence of pulsation during a no-load work by a hydraulic pump and to execute a hydraulic work during a load work without any trouble by a method wherein an adjusting valve for reducing the occurrence of pulsation to openably close a cylinder port communicated with a cylinder chamber on the delivery starting side of a port on the delivery side is arranged at a valve disc. CONSTITUTION: When, during the load work of a hydraulic pump having an adjusting valve 7, pressure oil is generated in an oil passage 47 communicated with a working part, the pressure oil flows through a communication passage 73 and pushes up a piston valve 7c against the force of a stretch spring 71, and a cylinder port 42a in the delivery starting end part of a port on the delivery side is closed by an upper surface 7a. Meanwhile, since, during a no-load work, pressure oil in the oil passage 47 is reduced, pressure oil in a valve chamber 70 is also reduced to the pressure, the stretch spring 71 is against the pressure, and piston valve 7c is lowered to a stopper ring 72. A pressure oil discharge gap H is formed between the cylinder port 42a and the upper surface 7a of the piston valve. Thus, pressure oil pressurized between port areas (a) is rapidly discharged at the delivery starting end of a port (d) on the deliver side.</p> |
