| 摘要 |
PURPOSE:To suppress vibration by installing an adjusting valve having a valve piece for opening and closing a communication hole in shiftable ways in the axial direction in a cylinder and forming an orifice hole or groove having a large resistance for the communication to the both oil chambers, onto a partitioning wall or the adjusting valve, thus permitting the speedy following to the speedy contraction and loosening of a belt. CONSTITUTION:When a belt is contracted at a high speed, a force acts onto a piston rod 32, and the pressure in the first oil chamber 34 increases. Then, an adjusting valve 38 closes a communication hole 37, and the oil O flows to the second oil chamber 35 side, passing through an orifice hole having a large resistance. The contraction of the piston rod 32 is suppressed by the resistance of the orifice hole. When the belt is loosened at a high speed on the contrary, a force in the direction for extending the piston rod 32 acts onto the piston rod 32 by a spring 33, and the pressure in the first oil chamber 34 lowers. Then,the adjusting valve 38 opens the communication hole 37, and the oil O in the second oil chamber 35 flows into the first oil chamber 34 side. Therefore, the piston rod 32 speedily extends, and an idler 13 follows the belt speedily, and vibration is suppressed, and the always stable power transmission can be achieved.
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