| 摘要 |
PURPOSE:To constantly control the amount of stroke of an idler for adjusting the tensile force of a caterpillar independently of the size of external force applied to the idler by providing a second cylinder with the smaller amount of stroke than that of a cylinder for adjusting the tensile force of the caterpillar in connection state. CONSTITUTION:When the external force pressing a rod 5 to an idler 6 that supports a caterpillar for a track-laying vehicle movably is applied, higher pressure than the pressure set by a deceleration valve 12 is generated in the head side chamber 7a of a first cylinder 2 and the respective chambers 20 and 22 on both sides of the sub piston 18 of a second cylinder 3. When the pressure reaches the preset pressure alphaof a second relief valve 24, the pressurized oil of the chamber 22 is exhausted to a tank 27 through the second relief valve 24 and such and the sub piston 18 is moved right against a screw 21. At the same time, the pressured oil of the chamber 7a is guided into the chamber 20 from a path 19 to the chamber 20 and a main piston 4 and the idler 6 is moved right. Besides, when excessively external force is applied suddenly to the idler 6, the main piston 4 and the idler 6 are moved right by the valve opening of the first relief valve 8. |
