Cranes
US4180171A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 29, 1977 |
| Grant date | Dec 25, 1979 |
| Priority date | — |
| Expiry date | Aug 29, 1997 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB66D1/52
- WIPO fieldHandling
- WIPO sectorMechanical engineering
Abstract
A crane with a crane rope; means for attaching a load to the crane rope; a crane winch having a drum on which the crane rope can be wound; a crane motor which can drive the crane winch for hauling in or letting out the crane rope; a measuring winch having a drum with a measuring line windable thereon of length sufficient to reach at least as far as the crane rope can reach; a measuring winch motor which can turn the measuring winch drum to wind in or out the measuring line; means for attaching the outer extremity of the measuring line, away from the drum, to the load to be lifted by the crane; first transducer means operated by the measuring winch to provide a displacement signal proportional to any change, in relation to a predetermined value, and having regard to sign, of the length of measuring line extending from the measuring winch drum to the load; and crane motor control means operable by the displacement signal to control the crane motor to haul in or let out the crane rope substantially in synchronism with any motion of the outer extremity of the measuring line.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.