Hydraulic power steering device

The present invention relates to a vehicle-use hydraulic power steering apparatus useable in a vehicle, the apparatus having a damper valve. In particular, the invention relates to a hydraulic power steering apparatus in which the dampering effect is changeable according to the number of revolutions of an internal combustion engine so that steering follow-up performance in a low speed range of the vehicle is improved and stability of steering in a high speed range is improved. A hydraulic power steering apparatus which is arranged so that a damper valve is disposed in hydraulic oil circuits and for connecting an oil passage selector valve in a gear box with right and left oil chambers of a power cylinder . The damper valve comprises a spool valve. And a control oil chamber of the spool valve is connected with a hydraulic oil feed passage for connecting a hydraulic pump which is driven by an internal combustion engine so as to discharge hydraulic oil, with the oil passage selector valve . Its back pressure chamber is connected with a hydraulic oil circulating passage for connecting the oil passage selector valve with a reservoir tank . Orifices and are provided in connecting oil passages and , such that when discharge oil pressure of the hydraulic pump rises, opening of the spool valve increase.