| 摘要 |
<p>The pivoting cantilever arm-barrier may be utilised on car park entrances or level railway crossings and is operated electro-magnetically. A core-plunger (1) with an extended stroke is displaced when a circuit is energised, and effects axial displacement of a chain (3) to rotate a chain wheel (5). The wheel constitutes the fulcrum of the arm (6) which pivots from the horizontal to the vertical position. The arm (6) returns to the horizontal under the action of a counterweight (4) attached to the chain (3). Rapid descent is prevented by a one-way brake mechanism (11) acting on the chain-wheel axle. The electromagnet may include a travel limiting stop.</p> |
