Heavy duty crane with self-retracting/erecting live mast
US5240129A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Jun 4, 1990 |
| Grant date | Aug 31, 1993 |
| Priority date | — |
| Expiry date | Jun 4, 2010 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB66C23/82
- WIPO fieldHandling
- WIPO sectorMechanical engineering
Abstract
A traveling crane incorporates a self-retracting/erecting live mast or the like, pivotally mounted on the base unit and capable of moving to and from a flipped, stowed position on the opposite side of vertical from the positions of the normal operating mode. A cable and winch is provided to raise and lower the mast during the normal operating mode and to move the mast toward the stowed position. A power cylinder operates to control the mast during retraction and to erect the mast from the stowed position. A control system operates the power cylinder to controllably move the mast during retraction/erection. Flexible pendants and telescopic guide links interconnect the cylinder with the mast and the base unit. Optimum operating angles are provided. The control system includes an electrical circuit and a hydraulic circuit, the hydraulic circuit having a restricted orifice to resist movement of the mast by gravity during retraction. The electrical circuit includes interlocks to disable the cable and winch at a selected angle and to place the cylinder in a free float mode during normal crane operation. The method includes the steps of pivotally moving the mast with the cable and winch, …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.