Multi-pulley telescopic mechanism and crane

A multi-pulley telescopic mechanism, comprising a telescopic mechanism, a first boom-extension rope, a second boom-extension rope, a third boom-extension rope, a basic boom, and a second boom, a third boom, a fourth boom and a fifth boom which are sequentially inlaid in the basic boom;

• a movable tail end of the telescopic mechanism is connected to the basic boom, a stationary tail end of the telescopic mechanism is connected to the second boom, a first boom-extension steering mechanism is mounted at a stationary front end of the telescopic mechanism, one end of the first boom-extension rope is fixedly connected to the third boom, an other end of the first boom-extension rope is wound around the first boom-extension steering mechanism and then fixedly connected to the basic boom, a first boom-extension steering assembly is mounted between the third boom and the fourth boom, one end of the second boom-extension rope is fixedly connected to the basic boom, an other end of the second boom-extension rope is wound around the first boom-extension steering assembly and then fixedly connected to the third boom, a second boom-extension steering assembly is mounted between the fourth boom and the fifth boom, one end of the third boom-extension rope is fixedly connected to the fifth boom, and an other end of the third boom-extension rope is wound around the second boom-extension steering assembly and then fixedly connected to the basic boom.