| 摘要 |
The equipment comprises a hollow support (2) for insertion in the ground, and a hollow cylindrical portion (1) which can be retracted into the interior of the support so as to allow free passage of a vehicle or extended to prevent it, guides being provided in the support for the retracting portion. The retracted or extended cylindrical portion is locked so that it can only be altered by the use of a key intended for the particular set of equipment and none other. A bolt (13) can be included, bearing against shoulders in the support and incorporated in the extending portion, and engaged or released by a key-operated lock in the latter. |
