| 摘要 |
<p>A SUPPORT OF VARIABLE LENGTH A variable length support comprises a rod telescopically received within a supporting tube. The rod is moved with respect to the tube by way of a drive roller which can also lock the rod with respect to the tube. The drive roller is mounted in an adjusting head carried by the tube and receiving the rod. The head has guide surfaces for the drive roller which is carried by a guide member pivotally connected to the head. The guide member is biased to ensure a positive engagement of the drive roller with the rod.</p> |
