| 摘要 |
972,417. Folding tower cranes. ETABLISSEMENTS F. POTAIN & CIE. March 27, 1963 [April 6, 1962], No. 12046/63. Heading B8B. A telescopic collapsibletower crane has a cable 25, Fig. 2, for telescoping the jib in conjunction with a winch 30, a raising cable 31 of constant length which extends from a point 31a on the counter-jib over pulleys 11, 14 to a support 3, a hoisting cable 32 connected to a winch 36 and an endless cable 37 driven by a winch 40, which displaces carriage 33 along the jib. To erect the crane from the Fig. 1 position; the tip 13. of the jib is folded down into alignment with the main part 12 and the winch 30 is operated with a ratchet 18 disengaged to extend a telescopic section 7 of the tower to the left, Fig. 2. This extension proceeds until a notch 9a, Fig. 6, abuts the ratchet 18 to arrest further movement to the left. Continued rotation of the winch 30 now moves a portion 9 of the tower to the right in Fig. 2 and that part of the cable 25 which passes round a pulley 26 causes the tower to swing into a vertical position about an axis 5. The tower is rocked in this position and the ratchet 18 again disengaged to permit further extension of the tower. This extension raises the jib to a horizontal position by means of the cable 31 and a stay 17. The crane is now locked in this' operational position. Further telescopic elements may be provided. |
