Raymond H Barker

US Patent:

44013370, Aug 30, 1983

Filed:

Nov 6, 1978

Appl. No.:

5/958016

Inventors:

Donald E. Simmons - Emeryville CA
Raymond H. Barker - Walnut Creek CA
Kenneth D. Walter - Foster City CA

Assignee:

Rigging International Maintenance Co. - Oakland CA

International Classification:

B66C 142

US Classification:

294 81SF

Abstract:

In a cargo container lifting crane employing a lifting spreader for lockingly suspending a cargo container by means of four corner twist locks, an improved electrical interlock system for interlocking the twist lock manual control switch located in the cab of the lifting crane, said interlock system including normally closed, parallel connected proximity switches which are disposed adjacent the twist locks of the lifting spreader and which are connected to a relay whereby the relay is de-energized to close a relay circuit which supplies power to the twist lock manual control switch when all of the four corner proximity switches indicate full engagement of all twist locks into the corresponding locking parts of the cargo container. An adjustable time delay is provided between full lifting spreader engagement and application of control switch power, and a by-pass switch is provided for overriding the interlock system. Also, indicating and alarm lights and horn are provided to alert crane maintenance and supervisory personnel, as well as the crane operator, of certain operating and alarm conditions in respect to the interlock system.