| 摘要 |
A hydraulic shock absorber has a case that includes an oil chamber, a cylinder and a reservoir chamber inside the case. A piston connected to a piston rod is fitted into the cylinder. A pump rod is fitted into a pump tube located inside the piston rod for forming a pump chamber. The pump chamber is communicated with an oil chamber through an oil passage and with a cylinder upper chamber through another oil passage. The motion of the pump rod caused by extension and retraction of the piston rod allows oil to flow from the oil chamber to the pump chamber and then to the cylinder upper chamber for extending the piston rod. When a vehicle height is increased to a normal height, cut-outs formed in the pump rod serve to communicate the pump chamber with the cylinder upper chamber for stopping the extension of the piston rod. When it becomes higher than the normal height, an orifice passage serves to relieve oil of the cylinder upper chamber to the oil chamber for lowering the vehicle height.
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