Crane, preferably a derrick crane

  • US 6,283,315 B1
  • Filed: 09/10/1999
  • Issued: 09/04/2001
  • Est. Priority Date: 09/11/1998
  • Status: Expired due to Term
First Claim
Patent Images

1. Crane comprisinga traveling chassis (1), a revolving superstructure (2) mounted on the chassis (1) in rotatable fashion, a boom and a derrick (30) each having first and second ends and each being connected to said revolving superstructure (2) at first ends thereof, and a ballast car (6) suspended from a second end of said derrick (30) by a tensional member (32) and additionally directly connected to the revolving superstructure (2) by a shaft (3) separately coupled to said superstructure (2) from said derrick (30), the ballast car (6) together with the tensional member (32) connected thereto, are mounted to be movable towards and away from the revolving superstructure (2) by adjusting length of the shaft (3), wherein the shaft (3) is in the form of at least two pipes (4, 5), one (5) telescoping into the other (4) and structured and arranged to be continuously telescoped even when the crane is operated under load, and means for automatically telescoping said telescoping shaft (3) even when said crane is under load and thereby adjusting length of said shaft (3) corresponding to load acting on the boom, are provided.

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