| 摘要 |
PROBLEM TO BE SOLVED: To set the maximum flow rate of a variable displacement pump in stages by means of a pilot hydraulic circuit with simple constitution. SOLUTION: A spool 36 is fittingly inserted into the sleeve 35 connected to a servo piston 30 for setting the slant angle in rotation for a variable displacement pump through a feedback lever 44, and a spring 37 is arranged in one end of this spool 36, and the small diameter section 47 of a pilot piston 38 is made to abut on the other end. By using a second hydraulic pressure chamber as a pressure source with pilot pressure working to a second hydraulic pressure chamber 54, the spool 36 is made to displace much resisting the spring force of the spring 37 to set the slant angle in rotation large corresponding to a first maximum flow rate Qmax1, and pilot pressure is led to a first hydraulic pressure chamber 50 to return a pilot piston 46 by means of an auxiliary piston 49 to make the spool 36 displace by spring force for changing the inclination angle in rotation for setting the flow rate to a second maximum flow rate Qmax2. |
