| 摘要 |
PURPOSE:To enable an increase in a control speed and to simplify constitution, by a method wherein a control linkage is coupled to 2 hydraulic cylinders through a bell crank, the hydraulic cylinders are normally energized through the force of springs, and are controlled by an electromagnetic control valve and an electromagnetic switching valve. CONSTITUTION:A hydraulic control device, which elevates a blade 3 of a laser beam induction system buldozer 6, is constituted such that a blade elevation control linkage 9 is pivotally coupled to a bell crank 17 pivotally located around a stationary fulcrum 18. Rods 29 and 30 of two hydraulic cylinders 25 and 26 are coupled to a circular groove 28 of the bell crank 17 to selectively actuate the two hydraulic cylinders 25 and 26. The rods 29 and 30 of the two hydraulic cylinders 25 and 26 are normally pressed through the force of springs 32 and 33, and pressure oil from a hydraulic pump 11 is fed to the hydraulic cylinders 25 and 26 through the working of an electromagnetic control valve 20 and an electromagnetic switching valve 21. This enables to perform rapid control through a lower control force, and permits simplification of a control mechanism and a hydraulic circuit. |
