| 摘要 |
PURPOSE:To prevent a shortage of pressure oil feed quantity immediately after steering operation and thereby make the steering operation evero so better, by setting a reference line of the pressure oil feed quantity to a high level, while compensating the pressure oil feed quantity for reduction. CONSTITUTION:A pressure oil feed passage 22 is jointly provided with an oil level control device 24 which controls the quantity of pressure oil feed from an oil pump 21 to a power cylinder 13. An oil level control device 24 is constituted of a solenoid valve gear 25 and a drain valve gear 26. The solenoid valve gear 25 has a solenoid 27 and a spool valve 28 whose stroke position is controlled by this solenoid 27, while the passage area of an orifice 29 is altered by the stroke position of the spool valve 28. In proportion as the quantity of a continuous rating current to the solenoid 27 increases, the spool valve 28 is shifted to the solenoid side, choking the orifice 29 to some extent, thus the pressure oil feed quantity is decreased. |
