| 摘要 |
PURPOSE:To facilitate an operation after maintenance and inspection, by a method wherein a solenoid valve, consisting of a valve for descending and a valve, releasing the back pressure of a descending cylinder into air when the descending valve is being closed, is connected to a detecting means detecting the back pressure of the descending cylinder. CONSTITUTION:A pressure switch 16 detects the back pressure of a descending cylinder in accordance with the elevation of a pantograph collector, thereby detecting the elevation of the same. On the other hand, a descending switch is pushed at first previous to the elevation of the pantograph collector when the maintenance and/or inspection of the same is effected. According to this operation, a descending solenoid valve 84 is operated and the descending pipeline F of an air reservoir 11 is connected, whereby the cylinder shaft of the descending cylinder contacts a cam. When the descending switch is released, the descending solenoid valve 84 returns, and air in the descending cylinder is discharged into air through an in-unit solenoid valve 15 and the descending solenoid valve 84. According to this method, a transient state due to maintenance and/or inspection may be eliminated.
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