| 摘要 |
A retractable bollard has a tubular socket (1) sunk upright into the ground, a power cable through its sealed lower end. A cylindrical intermediate housing (4) telescopes down into the socket (1) and is detachably sealed to it at ground level. The lower end (55) of the housing (4) contains a power unit (3) which is removably attached by a connector (50) to a tube (31) providing the upper part of the housing (4). This tube (31) receives a riser (2) which is telescoped up and down by a co-axial lead screw (74) driven through the connector (50) by the power unit (2). Control signals to the power unit (3) can be conveyed through the power cable or via an aerial down through the intermediate housing (4), which can be removed from the permanent socket (1) for maintenance, repair or replacement of its components. |
