| 摘要 |
One of the switch-point blades (10,11) engages a locking device when travelled by the trolley and so completes a connection to the rail connector (7), the device designed so as to release the blade when freed from the trolley. The blades can be arrested in position by an iron flat switch (8) set above the connector (7) and forming a V or bow from the front whose side rims face upwards and whose centre (8c) lies above the connector. Vertical spacing webs (12,13) rising from the respective blades have their axes (12a,13a) at their upper ends to carry respective wheels (16,17) bearing on the iron switch (8). At the bottom point (8c) of the switch, the locking device forms a trough (8d) which is engaged by the web wheels (16,17) when their respective blades (10,11) come under trolley load. A spring (30) fitted between a fixed point and movable parts, e.g. blades (10,11) or webs (12,13) applies load to the engaged wheel so as to release this when its blade comes off load.
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