| 摘要 |
Throughway barrier apparatus comprises a pair of housings (51, 52; 151, 152) to be sited one to each side of a throughway (58). Each housing is provided with an upstanding surface (53, 54) of magnetic material, the two surfaces (53, 54) facing one another. A movable device (65) is magnetically coupled to each upstanding surface, and drive means (60) are arranged to move the magnetically coupled device upwardly and downwardly of the surface (53, 54). A barrier element such as a chain, cable, boom or the like extends across the throughway (58), the barrier element (55; 155a, 155b) being in use connected to the two said movable devices (65) for movement therewith. Each said movable device (65) comprises a magnetic body (15) which has an outer cylindrical surface and radial end walls, is magnetically polarized axially of the cylindrical surface, and has a disc-like pole plate (14, 16) at each radial end of the cylindrical surface, the two disc-like pole plates (14, 16) having a like diameter greater than the diameter of the cylindrical surface. Each motor unit (62) is provided with a drive shaft (18) of square or other non-circular cross-section that is a loose fit within a bore (13) of like crosssectional shape extending through the magnetic body (15) of the movable device (65).
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