| 摘要 |
Apparatus for preventing two switches from being simultaneously closed. A pair of rollers are each movable in, and between the ends of, respective curved tracks. The rollers are each linked to a respective switch so that when its switch is closed, each roller is at the bottom of its track, and when its switch is open, each roller is at the top of its track. Each switch cannot operate if its roller cannot move. A yoke maintains the rollers a fixed distance apart so that each roller may be at the top of its track, one roller may be at the top of its track while the other roller is at the bottom of its track, and vice versa, but one roller cannot move away from the top of its track if the other roller is not at the top of its track and vice versa. If one switch attempts to close while the other switch is closed, the roller of the closed switch is pulled into a detent at the bottom of its track; the roller remains in the detent as long as the other switch attempts closure. The closed switch may reopen while its roller remains in the detent, preventing closure of the one switch until its attempt at closure ceases. If the switches attempt simultaneous closure, one roller is preferentially held at the top of its track, while the other roller moves to the bottom of its track.
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