| 摘要 |
PURPOSE:To conduct arrangement so that a lubrication oil agent to carry out lubrication between a piston and a cylinder tube may be retained on the outer periphery side of the piston excellently without being pushed back or dripping into an axial core side following the movements of the piston, in the case of a parking brake pedal damper device. CONSTITUTION:By providing at both the axial end outer periphery edges of a piston 12 a number of cutout grooves 74 whose sections that are right-angled to the axial core of the piston 12 are formed in V shapes and whose groove depths deepen the more on the end edge sides, a lubrication agent 70 such as grease is made to be retained in the cutout grooves 74 by its own surface tension. |
