| 摘要 |
PROBLEM TO BE SOLVED: To eliminate vibration of a power cylinder caused by pulsation of an oil pressure source and to improve steering feeling. SOLUTION: Two ports 35a and 35b of a hydraulic pump 34 and first and second working chambers 32a and 32b of a power cylinder 27 are respectively connected by a first passage 36a and a second passage 36b. A delivery valve 40 opening when a pressure of a hydraulic pump 34 side becomes bigger than a pressure of the working chamber 32a (32b) side and a one-way valve 41 constantly allowing only an inflow of hydraulic oil to the hydraulic pump 34 side from the working chamber 32a (32b) side are respectively provided in parallel in the first and second passages 36a and 36b. Since a dead zone for a portion of a valve opening pressure of the delivery valve 40 formed when the pressure of the hydraulic pump 34 side changes from increase to decrease, the pulsation of the hydraulic pump 34 side is not transmitted to the working chamber 32a (32b) side in a pressure fluctuation width for at least the portion of the valve opening pressure of the delivery valve 40. |
