| 摘要 |
A spring loaded pin is provided at both ends of the bottom rails of the movable side and an engageable head is fixedly mounted on each of the posts between which the movable side is mounted. The spring loaded pin is allowed to ride in a guiding track which is formed of a vertical elongated section and a return section provided at the top of the elongated section and as a continuation of the latter, the track being provided in the two posts mentioned above. A shoulder is formed in the elongated section above the junction between the return section and the elongated section The track has sloping down and rising portions to exert different resistances against the spring loaded pin indicating to the operator that locking is about to take place, that the movable side is about to be unlocked or is in the process of being lowered. This device is safer and easier to operate than presently known devices.
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