Heavy duty crane with self-retracting/erecting live mast

  • US 5,240,129 A
  • Filed: 06/04/1990
  • Issued: 08/31/1993
  • Est. Priority Date: 06/04/1990
  • Status: Expired due to Term
First Claim
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1. In combination with a mobile crane with a load handling boom, a self retracting/erecting live mast connected to said boom and with pivotal mounting on a base for boom control, said mast moving to and from a flipped, stowed position on the opposite side of vertical from the positions of the normal operating mode of the crane, comprising:

  • first power means for raising and lowering the mast about the pivotal mounting during the normal operating mode of the crane up to a substantially vertical position at approximately 90°

    to said base, and to move said mast through the 90° and

    toward the stowed position;

    second power means independent of said first power means engaging said mast in opposition to said first power means and the force of gravity on said mast for operation in the positions of the retraction/erection mode while maintaining the pivotal mounting; and

    counter balance control means to cause said second power means to controllably move said mast along the positions of the retraction/erection mode in conjunction with said first power means to and from the stowed positions;

    whereby said mast may be retracted/erected/operated on a self-contained basis.

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