| 摘要 |
<p>1,025,089. Hydraulic control systems. PARKER-HANNIFIN CORPORATION. Nov. 3, 1964 [Nov. 5, 1963], No. 44814/64. Heading F1P. [Also in Division H2] Energization of an electric motor 25 driving a pump 2 delivering hydraulic fluid to one or other side of a double-acting piston and cylinder device 3 through a manually-operated inlet and outlet spool valve 1 is effected by a switch 32 when the latter is activated by movement of the valve spool 20 from the neutral position shown to one or other of its operative positions. The valve housing 5 has an inlet 10 connected to feed passages 11 and branch passages 9 which in the neutral position of the spool are connected to a by-pass 7 leading to a supply tank 4 and on moving the spool 20 to the right against its centering spring 21 the switch 32 is closed thereby starting the motor under no load before spool land 26 closes connection between by-pass 7 and the righthand passage 9. At the same time a metering portion 27 of land 28 closes connection between by-pass 7 and the left-hand passage 9. Continued right-hand movement of left-hand land 28 connects feed passage 11 to a motor passage 12, 14 and fluid is exhausted by motor 3 through right-hand line 14, passage 12 to a return passage 15 leading to the tank 4. The spool-actuated switch 32 comprises a spring- biased plunger 52 having a head 54, which bridges a single contact 56 with one or other spaced pairs of contacts 48, 49 to energize a relay switch 57 in the motor circuit.</p> |
