| 摘要 |
The automatic vehicle control post has a column (A) that moves vertically in a shaft (B) set in the ground. The column is raised and lowered by a hydraulic or pneumatic actuator (E). The column is maintained on high position by springs (F) that are compressed when the column is lowered. The actuator is remotely controlled. The springs (F) are supported at the bottom by movable plates (H) set in a transverse support (G). For emergency lowering the plates (H) are moved sideways, allowing the springs to fall to the bottom of the shaft, and the post to fall to ground level. To restore normal operation hydraulic fluid is admitted to the bottom (P) of the actuator, which lifts the assembly till the springs (I) on the movable plate force it back to the normal state of supporting the main springs.
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