| 摘要 |
<p>1332579 Valves DEERE & CO 25 Oct 1971 [26 Oct 1970] 49390/71 Heading F2V A valve 10 for connecting one of the work ports 50, 52 of a double acting piston-cylinder 48 to a pump 16 and the other to a reservoir 14 has a valve member 58 biased by springs 82 to a neutral position (shown) and actuated by a lever 62. A cam 70 fixed to the lever shaft 64 has two recesses 74, 76 with one of which a roller 80 on a detent 78 engages when the lever is moved to actuate the piston-cylinder so that the valve member 58 is held in an end actuated position. Flow from the pump 16 to the valve 58 when actuated is via passages 20, 22, manually controlled rotary metering valve 42, passage 26, pressure-operated flow regulating valve 30 and outlet 34, 46. The pressure differential across valve 42 acts on the opposite sides of a piston 86 provided with a small diameter rod 100 acting on the detent and a large diameter rod 98 surrounded by a detent loading spring 96. While fluid flows to the valve member 58 the net fluid force on the piston is substantially zero and the spring 96 holds the detent roller 80 in recess 74 or 76. When the piston-cylinder 48 reaches the end of a stroke fluid flow ceases and the pressure equalizes on opposite sides of the piston 86 so that the net fluid force opposes the spring 96 and springs 82 can return the valve member 58 and cam 70 to neutral position, roller 80 being cammed out of its recess 74 or 76.</p> |
