| 摘要 |
An improved linkage assembly for operatively connecting a derail to a blue flag assembly to cause the blue flag assembly to be raised from a horizontal position between train track rails to a vertical position substantially perpendicular to the train track when the derail is manipulated into an operative mode for derailing a train, train car or similar type wheeled vehicle, and further provided with a stop device to inhibit accidental raising of the blue flag assembly until it is desired to do so. The linkage assembly is constructed having a support plate also mountable on adjacent cross ties, and further includes a blue flag mounting assembly to permit the blue flag signal to pivot between horizontal and vertical positions. The linkage assembly further including a spring loaded tensioning device attached at one end to the blue flag mounting assembly and attached at its opposite end to a cam assembly also mounted on the support plate. The cam assembly is operatively connected to a linkage arm which in turn is connected to the derail whereby the manipulation of the derail from its non-operative position to its operative, derailing position causes the blue flag signal to be pivoted from the horizontal to the vertical position and which locks out any change in the derail position by manipulation of the blue flag signal.
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