Extensible drive shaft

Claim 1

A DRIVE SHAFT OPERABLE TO BE EXTENDED AND RETRACTED WHILE TRANSMITTING POWER, SAID DRIVE SHAFT COMPRISING: (A) FIRST, SECOND AND THIRD SECTIONS TELESCOPED SUCCESSIVELY TOGETHER FOR RELATIVE SLIDING MOVEMENT PARALLEL TO THE AXIS OF THE SHAFT BUT SECURED AGAINST RELATIVE ROTATION ABOUT SAID SHAFT AXIS, SAID FIRST AND THIRD SECTIONS BEING OPERABLE TO ENGAGE EACH OTHER DIRECTLY WHEN THE SHAFT IS RETRACTED TO A TOTAL LENGTH LESS THAN THE COMBINED LENGTHS OF SAID FIRST AND THIRD SECTIONS, SAID FIRST AND THIRD SECTIONS WHEN SO ENGAGED BEING RELATIVELY SLIDABLE LONGITUDINALLY OF THE SHAFT BUT RELATIVELY NON-ROTATABLE ABOUT AN AXIS OF THE SHAFT, WHEREBY SAID SECOND OR INTERMEDIATE SHAFT IS RENDERED SUBSTANTIALLY INOPERATIVE, AND (B) A SPRING BIASING A SUCCESSIVE PAIR OF SAID SECTIONS TOWARD BUT NOT BEYOND AN EXTENDED POSITION IN WHICH THEY PROVIDE A MAXIMUM LENGTH BUT ARE STILL OPERATIVELY ENGAGED.