| 摘要 |
Telescopic mast consisting of coaxial tubes 1, 2, 3, 4, of erection means enabling each tube to be moved with respect to the previous one between its rest position and its active position, guiding means comprising, at the foot of the inner tube, a guide 10 interacting with the internal wall of the outer tube 1 and, at the head of the outer tube, a ring 8 interacting with the external wall of the inner tube 2, as well as locking means comprising a locking ring 9 capable of being locked on the guiding ring 8. In the locking position, the two rings 8, 9 interact by means of two frustoconical bearing surfaces 26, 27 whilst the guide comes to bear, also by means of two frustoconical bearing surfaces 23, 25, against the lower edge of a casing 24 installed in the external tube. By virtue of these frustoconical bearing surfaces, the mast is very stable. <IMAGE>
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