| 摘要 |
A pneumatic lift cylinder for scaffolds and having a plurality of telescopically arranged cylinder members which are extended sequentially in at least three steps of extension from the bottom up and retracted sequentially in at least three steps of retraction from the top down. In extension, after each member extends, it is overpressured, to rigidify the extended member before the next member is extended. In the retraction sequence, each of the cylinders below the retracting cylinder is maintained in an overpressured condition until its turn to retract.
|
