DAMPING FORCE ADJUSTING DEVICE FOR HYDRAULIC BUFFER

PURPOSE:To obtain the damping force characteristic in a wide range by installing the extension and contraction side leaf valves onto a piston and installing the first and second leaf valves over and below the third port and further installing a valve for adjusting the opening area of the bypass on the third port. CONSTITUTION:A bypass for allowing the third port 33 to communicate to a lower part oil chamber 21 is formed on a disc 50 and a piston rod 19, and a valve for adjusting the opening area of the bypass is installed in the bypass. When the bypass is in closed state, a high damping force in extension and retraction due to an extension side leaf valve 31 and a compression side leaf valve 53 is generated. Further, when the bypass is in opened state, a flow passage in the bypass and a flow passage on the first extension side and contraction leaf valves 31 and 53 are formed, and the first and second leaf valves 29 and 52 are opened successively in the speed range starting from the low speed to the intermediate speed, while in the high speed range, the extension and retraction side leaf valves 31 and 53 are opened, and the intermediate or low damping force corresponding to the opening area of the bypass is obtained by the valve control in the bypass.