| 摘要 |
<p>The barrier arm (9) is mounted via a horizontal driving shaft (2) in a column(1), and swings upwards from the horizontal blocking position into the opening position. The counterbalancing spring (8) aiding the opening movement has an unstressed neutral position (0) between the blocking (S) and opening (F) positions. The neutral position can be between angles of 30 and 40 deg., and the spring can have outer and inner bodies on the column and turning with the shaft respectively, with an elastic insert between them. The inner body and the outer one enclosing it can have the same number of corners which are offset.</p> |
