| 摘要 |
The height-adjustable support trestle for a working platform has two vertical posts for planks, joined together at the top by a traverse. Each part consists of a column on an underframe, in which is guided a hand-operated shaft parallel to the traverse, with gears meshing with recess rows in the posts. Two bolts drop between each post and its gear to lock the latter. They are lifted by the teeth, when the posts are raised, and are coupled by a component so that, when the first one is lifted by hand the second one is also lifted. The coupling between the bolts (25,25a) is automatically detached when the second one is lifted.
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