| 摘要 |
An improved joint and method of providing such a joint between the upper and lower portions of a rotatably driven crane post, comprising a sleeve-shaped member formed internally with screw threads and provided at the lower end of the upper position, a pin provided at the upper part of the lower post portion and formed externally with screw threads matching the sleeve member threads, and a collar on the lower post portion below the pin against which collar the sleeve-shaped member is pressed upon screwing together of the lower and upper post portions to form said joint. |
