| 摘要 |
A camera dolly or camera crane has an arm pivotably attached to a chassis, and a hydraulic system including a hydraulic cylinder for raising the arm, a hydraulic valve and a valve control. The hydraulic valve has a normal operation mode where opening and closing of the valve is controlled by the valve control. The hydraulic valve is also provided with a float down mode, where the valve remains partially open providing an intentional slight leakage, regardless of operation of the valve control. In float down mode, as soon as the arm reaches its highest point, the arm automatically and instantaneously reverses direction and starts to move back down, in a smooth continuous movement. The hydraulic system may optionally also include a fast down valve, to allow the arm to move down quickly, even when minimally loaded. |
